RESUMEN
OBJECTIVES: To describe serum C-reactive protein and S100A12 concentrations in dogs with hepatic disease and to determine whether there is a relationship between the concentration of either and the severity of hepatic necroinflammation. METHODS: Serum C-reactive protein and S100A12 concentrations were measured in 46 dogs undergoing hepatic biopsy. Dogs were divided into three groups: congenital portosystemic shunts, chronic hepatitis and hepatic neoplasia. The histological severity of hepatic necroinflammation was scored. RESULTS: C-reactive protein and S100A12 concentrations were greater than the upper limit of the reference intervals in 39 and 26% of dogs, respectively. There was no association of disease group with C-reactive protein (P=0·1733) or S100A12 (P=0·1513) concentrations. There was a positive correlation between serum C-reactive protein concentration and hepatic necroinflammatory activity (rs =0·428, P=0·006). CLINICAL SIGNIFICANCE: Increased serum C-reactive protein and S100A12 concentrations were observed in a subpopulation of dogs with various types of hepatic diseases, suggesting acute-phase inflammation and activation of phagocytic cells, respectively. Dogs with higher hepatic necroinflammatory activity scores tended to have higher serum C-reactive protein concentrations. Further studies are needed to confirm this finding in a larger group of dogs.
Asunto(s)
Biomarcadores/sangre , Proteínas Sanguíneas/metabolismo , Enfermedades de los Perros/sangre , Hepatopatías/sangre , Proteína S100A12/sangre , Animales , Enfermedades de los Perros/patología , Perros , Femenino , Masculino , Valor Predictivo de las Pruebas , Índice de Severidad de la EnfermedadRESUMEN
Hepatic microvascular dysplasia (HMD) is a disease involving a microscopic shunting of blood through the liver without the presence of a macroscopic portosystemic shunt (PSS). Data was collected from medical records and telephone conversations with referring veterinarians and owners of 24 dogs diagnosed with HMD. Criteria for diagnosis included histopathological evidence of microvascular dysplasia on hepatic biopsy as well as surgical exploration and a normal mesenteric portogram to rule out a macroscopic PSS. Dogs with HMD frequently have less severe clinical signs and a better long-term prognosis than do those with a PSS that are managed medically.
Asunto(s)
Enfermedades de los Perros/diagnóstico , Hepatopatías/veterinaria , Hígado/irrigación sanguínea , Animales , Diagnóstico Diferencial , Progresión de la Enfermedad , Enfermedades de los Perros/dietoterapia , Perros , Femenino , Estudios de Seguimiento , Hiperplasia , Hepatopatías/diagnóstico , Hepatopatías/dietoterapia , Masculino , Microcirculación , Sistema Porta/anomalías , Pronóstico , Registros/veterinaria , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
The role of three histidine residues (His205, His296 and His303) and Asp259, important for the catalysis of NAD+-specific D-lactate dehydrogenase, was investigated using site-directed mutagenesis. None of these residues is presumed to be involved in coenzyme binding because Km for NADH remained essentially unchanged for all the mutant enzymes. Replacement of His205 with lysine resulted in a 125-fold reduction in kcat and a slight lowering of the Km value for pyruvate. D259N mutant showed a 56-fold reduction in kcat and a fivefold lowering of Km. The enzymatic activity profile shifted towards acidic pH by approximately 2 units. The H303K mutation produced no significant change in kcat values, although Km for pyruvate increased fourfold. Substitution of His296 with lysine produced no significant change in kcat values or in Km for substrate. The results obtained suggest that His205 and Asp259 play an important role in catalysis, whereas His303 does not. This corroborates structural information available for some members of the D-specific dehydrogenases family. The catalytic His296, proposed from structural studies to be the active site acid/base catalyst, is not invariant. Its function can be accomplished by lysine and this has significant implications for the enzymatic mechanism.
Asunto(s)
Ácido Aspártico/fisiología , Proteínas Bacterianas/química , Histidina/fisiología , L-Lactato Deshidrogenasa/química , Lactato Deshidrogenasas , Lactobacillus/enzimología , NAD/fisiología , Sustitución de Aminoácidos , Proteínas Bacterianas/metabolismo , Sitios de Unión , Catálisis , Concentración de Iones de Hidrógeno , Cinética , L-Lactato Deshidrogenasa/aislamiento & purificación , L-Lactato Deshidrogenasa/metabolismo , Modelos Moleculares , Mutagénesis Sitio-Dirigida , Mutación Puntual , Proteínas Recombinantes de Fusión/aislamiento & purificación , Proteínas Recombinantes de Fusión/metabolismo , Relación Estructura-ActividadRESUMEN
OBJECTIVES: To use computer-assisted kinematic analysis to describe the walk in healthy dogs and to adapt Fourier transformation for analysis of the data. DESIGN: Evaluation of normal walk in dogs, using kinematic and force plate analysis. SAMPLE POPULATION: 15 healthy large-breed dogs. PROCEDURE: Morphometric data were collected to describe the sample population. Temporal and distance variables were measured to describe the walk. Flexion and extension movements were described for the scapulohumeral, cubital, carpal, coxofemoral, femorotibial, and tarsal joints. Fourier transformation was adapted to facilitate analysis of the joint angle waveforms. RESULTS: Unique and complex patterns of flexion and extension movements were observed for each joint studied. The walk had consistency of movement in the sample population in temporal and distance variables and joint movements. Variances attributable to intra- and interdog differences were similar and 1 to 2 orders of magnitude smaller than the mean Fourier coefficients from which they were calculated for all 6 joints. The number of essential Fourier coefficients required to represent the joint angle waveforms was 3 for the coxofemoral joint, 5 each for the femorotibial, scapulohumeral, cubital, and carpal joints, and 6 for the tarsal joint. CONCLUSIONS: Computer-assisted kinematic gait analysis proved to be a reliable and consistent technique for assessment of movement at the walk in dogs, and Fourier transformation was shown to be an effective tool for analysis of the kinematic data. CLINICAL RELEVANCE: The database derived from the normal sample population in this study can be used as a model of musculoskeletal function at the walk for future comparisons with disease and treatment.
Asunto(s)
Perros/fisiología , Marcha , Locomoción , Animales , Fenómenos Biomecánicos , Peso Corporal , Huesos , Análisis de Fourier , Articulaciones , Matemática , Modelos Biológicos , Movimiento , Grabación en VideoRESUMEN
OBJECTIVE: Noninvasive, computer-assisted, three-dimensional kinematic gait analysis was used to describe lameness in a chronic model of cranial cruciate ligament rupture (CCLR) in dogs. DESIGN: Hind limb lameness was evaluated prior to and at 1, 3, and 6 months after transection of the cranial cruciate ligament. ANIMALS: Seven clinically normal large dogs. PROCEDURE: Dynamic flexion and extension angles and angular velocities were calculated for the coxofemoral, femorotibial, and tarsal joints. Distance and temporal variables were determined. Essential Fourier coefficients were used to develop mean flexion extension curves for all joints and to compare changes in movement that developed with CCLR over time. RESULTS: Each joint had a characteristics pattern of flexion and extension movement that changed with CCLR. The femorotibial joint angle was more flexed throughout stance and early swing phase of stride and failed to extend in late stance. Angular velocity of the femorotibial joint was damped throughout stance phase, with extension velocity almost negligible. The coxofemoral and tarsal joint angles, in contrast to the femorotibial joint angle, were extended more during stance phase. These changes were documented as differences noted in the essential Fourier coefficients. Stride length and frequency also varied significantly after CCLR. CONCLUSIONS: Cranial cruciate ligament rupture affects movement of the coxofemoral and tarsal joints, as well as the femorotibial joint, in gait. A pattern of joint movement may be discerned in which the coxofemoral and tarsal joints compensate for the dysfunction of the femorotibial joint. CLINICAL RELEVANCE: Methods were developed that will improve objective evaluation of CCLR and its treatment in dogs.
Asunto(s)
Marcha , Artropatías/fisiopatología , Ligamentos Articulares , Análisis de Varianza , Animales , Perros , Fémur , Análisis de Fourier , Miembro Posterior , Rotura , Tibia , Factores de Tiempo , Grabación en Video/métodosRESUMEN
The medical records of 65 dogs that underwent complete or partial ligation of a single congenital portosystemic shunt (CPSS) were reviewed to determine the long-term clinical clinical results. Information retrieved from the records included age at surgery, preligation (baseline) portal pressure, postligation portal pressure, change in portal pressure from baseline, complete or partial occlusion of the shunting vessel and fasting, and 2-hour postprandial bile acids from the preoperative, early postoperative (PO), and greater than 1 year PO time periods. A clinical rating score derived from a follow-up examination greater than 1 year PO was assigned to each dog. Of the 56 dogs that survived the perioperative period, 29 (52%) had complete and 27 (48%) had partial ligations. Age at surgery, pre- and postligation portal pressure, change in portal pressure from baseline and serum bile acid concentrations were not related to long-term clinical outcome. Clinical rating scores were significantly greater for dogs with partial CPSS ligations compared with dogs with complete ligations, indicating a less favorable clinical outcome for partial ligations. Fasting and 2-hour postprandial bile acid values at both PO time intervals were significantly greater in partial versus complete ligation groups. Follow-up information for more than 1 year was available on 18 of 29 dogs (62%) with complete ligations. All were clinically normal. Of 27 dogs with partial ligations, 11 dogs (41%) developed recurrence of clinical signs resulting in presentation to the university or referring veterinarian for additional surgery, medical management, or euthanasia. Only three dogs with partial CPSS ligation (11%) were clinically normal.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Enfermedades de los Perros/cirugía , Sistema Porta/anomalías , Animales , Ácidos y Sales Biliares/análisis , Enfermedades de los Perros/congénito , Enfermedades de los Perros/fisiopatología , Perros , Femenino , Ligadura/veterinaria , Estudios Longitudinales , Masculino , Presión Portal/fisiología , Sistema Porta/cirugía , Pronóstico , Recurrencia , Estudios RetrospectivosRESUMEN
Necrotizing sialometaplasia (NS) is a distinct, though rare disease of the salivary glands. Histologic findings in humans and dogs are identical, but the distribution of affected glands and clinical course are very different. Small terrier breeds are predisposed. Clinically, canine NS is characterized by nausea (i.e., ptyalism, lip smacking, gulping), dysphagia, and pain in the mandibular region. Surgical removal of the affected glands produces minimal, if any, improvement; however, transient administration of anticonvulsants has resulted in dramatic clinical improvement in three cases.
Asunto(s)
Enfermedades de los Perros , Sialometaplasia Necrotizante/veterinaria , Animales , Enfermedades de los Perros/tratamiento farmacológico , Enfermedades de los Perros/cirugía , Perros , Femenino , Fenobarbital/uso terapéutico , Glándulas Salivales/patología , Glándulas Salivales/cirugía , Sialometaplasia Necrotizante/tratamiento farmacológico , Sialometaplasia Necrotizante/cirugíaRESUMEN
Fifty-four dogs with primary tumors of the rib were evaluated. Thirty-four dogs had osteosarcomas, 15 dogs had chondrosarcomas, three dogs had hemangiosarcomas, and two dogs had fibrosarcomas. Forty-nine dogs had en bloc excision. Within the osteosarcoma group, nine animals received postoperative adjuvant chemotherapy. These animals had significantly longer median disease-free intervals (225 days) and median survival times (240 days) than dogs with osteosarcoma treated by surgery alone (median disease-free interval, 60 days; median survival, 90 days). Chondrosarcoma had a better prognosis (median disease-free interval, 1,080 days; median survival, 1,080 days) than osteosarcoma, hemangiosarcoma, or fibrosarcoma of the rib. Age, weight, sex, number of ribs resected, tumor volume, and total cisplatin dose did not influence survival nor disease-free interval.
Asunto(s)
Neoplasias Óseas/veterinaria , Condrosarcoma/veterinaria , Enfermedades de los Perros/cirugía , Osteosarcoma/veterinaria , Costillas , Animales , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Peso Corporal , Neoplasias Óseas/tratamiento farmacológico , Neoplasias Óseas/mortalidad , Neoplasias Óseas/cirugía , Quimioterapia Adyuvante/veterinaria , Condrosarcoma/tratamiento farmacológico , Condrosarcoma/mortalidad , Condrosarcoma/cirugía , Cisplatino/administración & dosificación , Cisplatino/efectos adversos , Cisplatino/uso terapéutico , Supervivencia sin Enfermedad , Enfermedades de los Perros/tratamiento farmacológico , Enfermedades de los Perros/mortalidad , Perros , Doxorrubicina/administración & dosificación , Doxorrubicina/efectos adversos , Femenino , Fibrosarcoma/tratamiento farmacológico , Fibrosarcoma/mortalidad , Fibrosarcoma/cirugía , Fibrosarcoma/veterinaria , Hemangiosarcoma/tratamiento farmacológico , Hemangiosarcoma/mortalidad , Hemangiosarcoma/cirugía , Hemangiosarcoma/veterinaria , Tablas de Vida , Masculino , Recurrencia Local de Neoplasia/veterinaria , Osteosarcoma/tratamiento farmacológico , Osteosarcoma/mortalidad , Osteosarcoma/cirugía , Pronóstico , Estudios Retrospectivos , Costillas/cirugía , Análisis de SupervivenciaRESUMEN
The nifS gene was first identified in nitrogen-fixing bacteria where its protein product is essential for efficient nitrogen fixation. Here, we demonstrate that a nifS-like gene also occurs in Lactobacillus bulgaricus, an organism which does not fix nitrogen, and that the nifS gene product suppresses the leucine auxotrophy of an ilvD, ilvE Escherichia coli strain. The known nifS genes from prokaryotes and eukaryotes exhibit a high degree of sequence conservation although the genes have diverse functions, as shown by their ability to complement or suppress dissimilar mutations. It was suggested that the nifS gene products represent a group of enzymes which mediate a specific chemical reaction common to diverse metabolic pathways. The purified NifS protein from Azotobacter vinelandii was experimentally shown to be a pyridoxal phosphate-dependent cysteine desulfurase. Curiously, the NifS proteins exhibit also a remarkable sequence homology to a new class of pyridoxal phoshate-dependent aminotransferases. We show that the L bulgaricus NifS-like protein is able to replace in vivo transaminase B in E coli. This experimental observation supports the prediction that some NifS-like proteins may be aminotransferases.
Asunto(s)
Proteínas Bacterianas/genética , Escherichia coli/enzimología , Lactobacillus/genética , Supresión Genética , Transaminasas/genética , Secuencia de Aminoácidos , Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Leucina/biosíntesis , Datos de Secuencia Molecular , Mutación , Fijación del Nitrógeno , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Transaminasas/metabolismoRESUMEN
Recently, we amplified the Lactobacillus bulgaricus NAD(+)-dependent D-lactate dehydrogenase gene by the polymerase chain reaction, cloned and overexpressed it in Escherichia coli (Kochhar, S., Chuard, N., and Hottinger, H. (1992) Biochem. Biophys. Res. Commun. 185, 705-712). Polymerase chain reaction-amplified DNA fragments may contain base changes resulting in mutant gene products. A comparison of specific activities of D-lactate dehydrogenase in the crude extracts of 50 recombinant clones indicated that one of the clones had drastically reduced enzyme activity. Nucleotide sequence analysis of the insert DNA showed an exchange of A to G at position 795 resulting in substitution of Glu264 to Gly in the D-lactate dehydrogenase. The purified mutant D-lactate dehydrogenase showed a shift of 2 units in its optimum pH toward the acidic range. The dependence of kcat/Km on the pH of the mutant enzyme showed that the pKa of the free enzyme was around 4, at least 2 pH units lower than that of the wild-type enzyme. Both the wild-type and the mutant enzyme at their respective optimum pH values showed similar kcat and Km values. The data suggest that the highly conserved Glu264 is not critical for enzyme catalysis, but it must be situated within hydrogen bonding distance to amino acid residue(s) involved in substrate binding as well as in catalysis.
Asunto(s)
Glutamatos/fisiología , L-Lactato Deshidrogenasa/metabolismo , Lactato Deshidrogenasas , Secuencia de Aminoácidos , Electroforesis en Gel de Poliacrilamida , Ácido Glutámico , Concentración de Iones de Hidrógeno , Cinética , Lactobacillus/enzimología , Datos de Secuencia Molecular , Oxidación-Reducción , Piruvatos/química , Ácido Pirúvico , Proteínas Recombinantes/metabolismoRESUMEN
NAD(+)-dependent D-lactate dehydrogenase from Lactobacillus helveticus was purified to apparent homogeneity, and the sequence of the first 36 amino acid residues determined. Using forward and reverse oligonucleotide primers, based on the N-terminal sequence and amino acid residues 220-215 of the Lactobacillus bulgaricus enzyme [Kochhar, S., Hunziker, P. E., Leong-Morgenthaler, P. & Hottinger, H. (1992) J. Biol. Chem. 267, 8499-8513], a 0.6-kbp DNA fragment was amplified from L. helveticus genomic DNA by the polymerase chain reaction. This amplified DNA fragment was used as a probe to identify two recombinant clones containing the D-lactate dehydrogenase gene. Both plasmids overexpressed D-lactate dehydrogenase (greater than 60% total soluble cell protein) and were stable in Escherichia coli, compared to plasmids carrying the L. bulgaricus and Lactobacillus plantarum genes. The entire nucleotide sequence of the L. helveticus D-lactate dehydrogenase gene was determined. The deduced amino acid sequence indicated a polypeptide consisting of 336 amino acid residues, which showed significant amino acid sequence similarity to the recently identified family of D-2-hydroxy-acid dehydrogenases [Kochhar, S., Hunziker, P. E., Leong-Morgenthaler, P. & Hottinger, H. (1992) Biochem. Biophys. Res. Commun. 184, 60-66]. The physicochemical and catalytic properties of recombinant D-lactate dehydrogenase were identical to those of the wild-type enzyme, e.g. alpha 2 dimeric subunit structure, isoelectric pH, Km and Kcat for pyruvate and other 2-oxo-acid substrates. The kinetic profiles of 2-oxo-acid substrates showed some marked differences from that of L-lactate dehydrogenase, suggesting different mechanisms for substrate binding and specificity.
Asunto(s)
L-Lactato Deshidrogenasa/genética , Lactato Deshidrogenasas , Lactobacillus/genética , Oxidorreductasas de Alcohol/química , Secuencia de Aminoácidos , Secuencia de Bases , Clonación Molecular , ADN Bacteriano/genética , Escherichia coli/genética , Expresión Génica , Concentración de Iones de Hidrógeno , Punto Isoeléctrico , L-Lactato Deshidrogenasa/aislamiento & purificación , L-Lactato Deshidrogenasa/metabolismo , Lactobacillus/enzimología , Datos de Secuencia Molecular , Peso Molecular , ARN Mensajero/genética , Proteínas Recombinantes/química , Mapeo Restrictivo , Alineación de SecuenciaRESUMEN
A 3.3-kb BamHI fragment of Lactobacillus delbrueckii subsp. bulgaricus DNA was cloned and sequenced. It complements an Escherichia coli glnA deletion strain and hybridizes strongly to a DNA containing the Bacillus subtilis glnA gene. DNA sequence analysis of the L. delbrueckii subsp. bulgaricus DNA showed it to contain the glnA gene encoding class I glutamine synthetase, as judged by extensive homology with other prokaryotic glnA genes. The sequence suggests that the enzyme encoded in this gene is not controlled by adenylylation. Based on a comparison of glutamine synthetase sequences, L. delbrueckii subsp. bulgaricus is much closer to gram-positive eubacteria, especially Clostridium acetobutylicum, than to gram-negative eubacteria and archaebacteria. The fragment contains another open reading frame encoding a protein of unknown function consisting of 306 amino acids (ORF306), which is also present upstream of glnA of Bacillus cereus. In B. cereus, a repressor gene, glnR, is found between the open reading frame and glnA. Two proteins encoded by the L. delbrueckii subsp. bulgaricus gene were identified by the maxicell method; the sizes of these proteins are consistent with those of the open reading frames of ORF306 and glnA. The lack of a glnR gene in the L. delbrueckii subsp. bulgaricus DNA in this position may indicate a gene rearrangement or a different mechanism of glnA gene expression.
Asunto(s)
Genes Bacterianos , Glutamato-Amoníaco Ligasa/genética , Lactobacillus/genética , Secuencia de Aminoácidos , Escherichia coli/genética , Vectores Genéticos , Glutamato-Amoníaco Ligasa/clasificación , Glutamato-Amoníaco Ligasa/aislamiento & purificación , Lactobacillus/enzimología , Datos de Secuencia Molecular , Plásmidos , Homología de Secuencia de AminoácidoRESUMEN
The Lactobacillus bulgaricus NAD(+)-dependent D-lactate dehydrogenase gene was amplified by the polymerase chain reaction and cloned into an Escherichia coli expression plasmid pKK223.3. Attempts to clone the full-length chromosomal DNA encoding D-lactate dehydrogenase from a partial Sau3AI lambda phage library or an enriched clone bank in E. coli were unsuccessful. The recombinant plasmid pKBULDH containing the amplified gene overexpressed D-lactate dehydrogenase (greater than 30% of total soluble protein) following induction of the tac promotor with isopropyl-beta-D-thiogalactopyranoside. The cloned gene product was purified to homogeneity by two chromatographic steps with 76% recovery of enzyme activity. All the properties of the recombinant protein, e.g., optimum pH and temperature, Km and k(cat) for pyruvate as well as for other 2-oxo acids and the subunit structure were identical to the wild-type enzyme.
Asunto(s)
Genes Bacterianos , L-Lactato Deshidrogenasa/genética , Lactato Deshidrogenasas , Lactobacillus/genética , Secuencia de Aminoácidos , Secuencia de Bases , Clonación Molecular , L-Lactato Deshidrogenasa/química , Lactobacillus/enzimología , Datos de Secuencia Molecular , Oligodesoxirribonucleótidos/química , Reacción en Cadena de la Polimerasa , Proteínas Recombinantes/química , Proteínas Recombinantes/aislamiento & purificación , Mapeo RestrictivoRESUMEN
The NAD(+)-dependent D-lactate dehydrogenase was purified to apparent homogeneity from Lactobacillus bulgaricus and its complete amino acid sequence determined. Two gaps in the polypeptide chain (10 residues) were filled by the deduced amino acid sequence of the polymerase chain reaction amplified D-lactate dehydrogenase gene sequence. The enzyme is a dimer of identical subunits (specific activity 2800 +/- 100 units/min at 25 degrees C). Each subunit contains 332 amino acid residues; the calculated subunit M(r) being 36,831. Isoelectric focusing showed at least four protein bands between pH 4.0 and 4.7; the subunit M(r) of each subform is 36,000. The pH dependence of the kinetic parameters, Km, Vm, and kcat/Km, suggested an enzymic residue with a pKa value of about 7 to be involved in substrate binding as well as in the catalytic mechanism. Treatment of the enzyme with group-specific reagents 2,3-butanedione, diethylpyrocarbonate, tetranitromethane, or N-bromosuccinimide resulted in complete loss of enzyme activity. In each case, inactivation followed pseudo first-order kinetics. Inclusion of pyruvate and/or NADH reduced the inactivation rates manyfold, indicating the presence of arginine, histidine, tyrosine, and tryptophan residues at or near the active site. Spectral properties of chemically modified enzymes and analysis of kinetics of inactivation showed that the loss of enzyme activity was due to modification of a single arginine, histidine, tryptophan, or tyrosine residue. Peptide mapping in conjunction with peptide purification and amino acid sequence determination showed that Arg-235, His-303, Tyr-101, and Trp-19 were the sites of chemical modification. Arg-235 and His-303 are involved in the binding of 2-oxo acid substrate whereas other residues are involved in binding of the cofactor.
Asunto(s)
Aminoácidos/genética , L-Lactato Deshidrogenasa/metabolismo , NAD/metabolismo , Secuencia de Aminoácidos , Secuencia de Bases , Sitios de Unión , Western Blotting , Cromatografía Líquida de Alta Presión , Electroforesis en Gel de Poliacrilamida , Concentración de Iones de Hidrógeno , Focalización Isoeléctrica , Cinética , L-Lactato Deshidrogenasa/antagonistas & inhibidores , L-Lactato Deshidrogenasa/genética , L-Lactato Deshidrogenasa/aislamiento & purificación , Lactobacillus/enzimología , Datos de Secuencia Molecular , Oxidación-Reducción , Reacción en Cadena de la Polimerasa , Piruvatos/metabolismo , Ácido Pirúvico , Especificidad por SustratoRESUMEN
A comparison of the primary structures of NAD(+)-dependent D-lactate dehydrogenase with L-lactate dehydrogenase and L-malate dehydrogenase failed to show any sequence similarity. However, D-2-hydroxyisocaproate dehydrogenase from Lactobacillus casei, glycerate dehydrogenase from cucumber, D-3-phosphoglycerate dehydrogenase and erythronate 4-phosphate dehydrogenase from Escherichia coli showed 38%, 24%, 24% and 22% amino acid identity, respectively. The profile analysis of the aligned sequences confirmed their relatedness. The hydropathy profiles of the aligned dehydrogenases were almost identical between residues 100-300 indicating largely preserved folding patterns of their polypeptide chains. The data suggest that L- and D-specific 2-hydroxy acid dehydrogenase genes evolved from two different ancestors and thus represent two different sets of enzyme families.
Asunto(s)
Oxidorreductasas de Alcohol/genética , Evolución Biológica , Deshidrogenasas de Carbohidratos/genética , Proteínas de Escherichia coli , L-Lactato Deshidrogenasa/genética , Secuencia de Aminoácidos , Bases de Datos Factuales , Escherichia coli/genética , Lacticaseibacillus casei/genética , Datos de Secuencia Molecular , NAD/metabolismo , Fosfoglicerato-Deshidrogenasa , Plantas/enzimología , Conformación Proteica , Homología de Secuencia de Ácido Nucleico , Programas InformáticosRESUMEN
The genes coding for the lactose permease and beta-galactosidase, two proteins involved in the metabolism of lactose by Lactobacillus bulgaricus, have been cloned, expressed, and found functional in Escherichia coli. The nucleotide sequences of these genes and their flanking regions have been determined, showing the presence of two contiguous open reading frames (ORFs). One of these ORFs codes for the lactose permease gene, and the other codes for the beta-galactosidase gene. The lactose permease gene is located in front of the beta-galactosidase gene, with 3 bp in the intergenic region. The two genes are probably transcribed as one operon. Primer extension studies have mapped a promoter upstream from the lactose permease gene but not the beta-galactosidase gene. This promoter is similar to those found in E. coli with general characteristics of GC-rich organisms. In addition, the sequences around the promoter contain a significantly higher number of AT base pairs (80%) than does the overall L. bulgaricus genome, which is rich in GC (GC content of 54%). The amino acid sequences obtained from translation of the ORFs are found to be highly homologous (similarity of 75%) to those from Streptococcus thermophilus. The first 460 amino acids of the lactose permease shows homology to the melibiose transport protein of E. coli. Little homology was found between the lactose permease of L. bulgaricus and E. coli, but the residues which are involved in the binding and the transport of lactose are conserved. The carboxy terminus is similar to that of the enzyme III of several phosphoenolpyruvate-dependent phosphotransferase systems.
Asunto(s)
Proteínas de Escherichia coli , Genes Bacterianos , Lactobacillus/metabolismo , Lactosa/metabolismo , Proteínas de Transporte de Membrana/genética , Proteínas de Transporte de Monosacáridos , Simportadores , beta-Galactosidasa/genética , Secuencia de Bases , Clonación Molecular , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Regiones Promotoras Genéticas , ARN Bacteriano/genética , ARN Mensajero/genética , Secuencias Reguladoras de Ácidos Nucleicos , Mapeo Restrictivo , Especificidad de la EspecieRESUMEN
From a genomic DNA library of Lactobacillus delbrueckii subsp. bulgaricus, a clone was isolated which complements a leucine auxotrophy of an Escherichia coli strain (GE891). Subsequent analysis of the clone indicated that it could serve as a specific DNA probe. Dot-blot hybridizations with over 40 different Lactobacillus strains showed that this clone specifically recognizes L. delbrueckii subsp. delbrueckii, bulgaricus, and lactis. The sensitivity of the method was tested by using an alpha-P-labeled DNA probe.