RESUMEN
Freezing temperatures are a major challenge for life at the poles. Decreased membrane fluidity, uninvited secondary structure formation in nucleic acids, and protein cold-denaturation all occur at cold temperatures. Organisms adapted to polar regions possess distinct mechanisms that enable them to survive in extremely cold environments. Among the cold-induced proteins, cold shock protein (Csp) family proteins are the most prominent. A gene coding for a Csp-family protein, cspB, was cloned from an arctic bacterium, Polaribacter irgensii KOPRI 22228, and overexpression of cspB greatly increased the freeze-survival rates of Escherichia coli hosts, to a greater level than any previously reported Csp. It also suppressed the cold-sensitivity of an E. coli csp-quadruple deletion strain, BX04. Sequence analysis showed that this protein consists of a unique domain at its N-terminal end and a well conserved cold shock domain at its C-terminal end. The most common mechanism of Csp function in cold adaption is melting of the secondary structures in RNA and DNA molecules, thus facilitating transcription and translation at low temperatures. P. irgensii CspB bound to oligo(dT)-cellulose resins, suggesting single-stranded nucleic acid-binding activity. The unprecedented level of freeze-tolerance conferred by P. irgensii CspB suggests a crucial role for this protein in survival in polar environments.(AU)
Asunto(s)
Flavobacteriaceae/fisiología , Proteínas y Péptidos de Choque por Frío , Frío Extremo , Clima FríoRESUMEN
ABSTRACT Freezing temperatures are a major challenge for life at the poles. Decreased membrane fluidity, uninvited secondary structure formation in nucleic acids, and protein cold-denaturation all occur at cold temperatures. Organisms adapted to polar regions possess distinct mechanisms that enable them to survive in extremely cold environments. Among the cold-induced proteins, cold shock protein (Csp) family proteins are the most prominent. A gene coding for a Csp-family protein, cspB, was cloned from an arctic bacterium, Polaribacter irgensii KOPRI 22228, and overexpression of cspB greatly increased the freeze-survival rates of Escherichia coli hosts, to a greater level than any previously reported Csp. It also suppressed the cold-sensitivity of an E. coli csp-quadruple deletion strain, BX04. Sequence analysis showed that this protein consists of a unique domain at its N-terminal end and a well conserved cold shock domain at its C-terminal end. The most common mechanism of Csp function in cold adaption is melting of the secondary structures in RNA and DNA molecules, thus facilitating transcription and translation at low temperatures. P. irgensii CspB bound to oligo(dT)-cellulose resins, suggesting single-stranded nucleic acid-binding activity. The unprecedented level of freeze-tolerance conferred by P. irgensii CspB suggests a crucial role for this protein in survival in polar environments.
Asunto(s)
Proteínas Bacterianas/metabolismo , Flavobacteriaceae/fisiología , Proteínas y Péptidos de Choque por Frío/metabolismo , Regiones Árticas , Proteínas Bacterianas/genética , Regulación Bacteriana de la Expresión Génica , Frío , Ecosistema , Flavobacteriaceae/aislamiento & purificación , Flavobacteriaceae/genética , Proteínas y Péptidos de Choque por Frío/genéticaRESUMEN
Freezing temperatures are a major challenge for life at the poles. Decreased membrane fluidity, uninvited secondary structure formation in nucleic acids, and protein cold-denaturation all occur at cold temperatures. Organisms adapted to polar regions possess distinct mechanisms that enable them to survive in extremely cold environments. Among the cold-induced proteins, cold shock protein (Csp) family proteins are the most prominent. A gene coding for a Csp-family protein, cspB, was cloned from an arctic bacterium, Polaribacter irgensii KOPRI 22228, and overexpression of cspB greatly increased the freeze-survival rates of Escherichia coli hosts, to a greater level than any previously reported Csp. It also suppressed the cold-sensitivity of an E. coli csp-quadruple deletion strain, BX04. Sequence analysis showed that this protein consists of a unique domain at its N-terminal end and a well conserved cold shock domain at its C-terminal end. The most common mechanism of Csp function in cold adaption is melting of the secondary structures in RNA and DNA molecules, thus facilitating transcription and translation at low temperatures. P. irgensii CspB bound to oligo(dT)-cellulose resins, suggesting single-stranded nucleic acid-binding activity. The unprecedented level of freeze-tolerance conferred by P. irgensii CspB suggests a crucial role for this protein in survival in polar environments.
Asunto(s)
Proteínas Bacterianas/metabolismo , Proteínas y Péptidos de Choque por Frío/metabolismo , Flavobacteriaceae/fisiología , Regiones Árticas , Proteínas Bacterianas/genética , Proteínas y Péptidos de Choque por Frío/genética , Frío , Ecosistema , Flavobacteriaceae/genética , Flavobacteriaceae/aislamiento & purificación , Regulación Bacteriana de la Expresión GénicaRESUMEN
A bacterial strain, UST030701-156T, was isolated from a marine sponge in the Bahamas. Strain UST030701-156T was orange-pigmented, Gram-negative, rod-shaped with tapered ends, slowly motile by gliding and strictly aerobic. The predominant fatty acids were a15 : 0, i15 : 0, i15 : 0 3-OH, i17 : 0 3-OH, i17 : 1omega9c and summed feature 3, comprising i15 : 0 2-OH and/or 16 : 1omega7c. MK-6 was the only respiratory quinone. Flexirubin-type pigments were not produced. Phylogenetic analysis based on 16S rRNA gene sequences placed UST030701-156T within a distinct lineage in the family Flavobacteriaceae, with 93.3 % sequence similarity to the nearest neighbour, Nonlabens tegetincola. The DNA G+C content of UST030701-156T was 41.0 mol% and was much higher than that of N. tegetincola (33.6 mol%). Strain UST030701-156T can be distinguished from other members of the Flavobacteriaceae by means of a number of chemotaxonomic and phenotypic characteristics. It is proposed, therefore, that UST030701-156T represents a novel taxon designated Stenothermobacter spongiae gen. nov., sp. nov. The type strain is UST030701-156T (= NRRL B-41138T = JCM 13191T). Carbon-source utilization by N. tegetincola was re-examined and an emended description is therefore included.
Asunto(s)
Flavobacteriaceae/clasificación , Poríferos/microbiología , Agua de Mar/microbiología , Aerobiosis , Animales , Bahamas , Composición de Base , Carbono/metabolismo , Ácidos Grasos , Flavobacteriaceae/química , Flavobacteriaceae/aislamiento & purificación , Flavobacteriaceae/fisiología , Datos de Secuencia Molecular , ARN Bacteriano/genética , ARN Ribosómico 16S/genética , Homología de Secuencia de Ácido Nucleico , Especificidad de la Especie , Vitamina K 2/análogos & derivadosRESUMEN
A Gram-negative, rod-shaped bacterium (designated strain UST030701-295(T)) with fast gliding motility was isolated from the surface of the sponge Lissodendoryx isodictyalis in the Bahamas. Colonies of UST030701-295(T) were yellow in colour, 2-4 mm in diameter, convex with a smooth surface and entire margins. UST030701-295(T) was heterotrophic, strictly aerobic and required NaCl for growth (1.0-4.0%). Growth was observed at pH 6.0-10.0 and at 12-44 degrees C. Phylogenetic analysis of the 16S rRNA gene sequence placed UST030701-295(T) within the genus Winogradskyella of the family Flavobacteriaceae, sharing 94.7-95.8% similarity with the three recognized members of the genus. The G+C content of the DNA was 32.8 mol% and the predominant fatty acids were iso-C(15:1), iso-C(15:0), iso-C(15:0) 2-OH, iso-C(15:0) 3-OH, iso-C(16:0) 3-OH, C(16:1)omega7 and iso-C(17:0) 3-OH (together representing 75.4% of the total); these data supported the affiliation of UST030701-295(T) to the genus Winogradskyella. UST030701-295(T) differed from the three recognized species of Winogradskyella in 7-17 traits. Molecular evidence together with phenotypic characteristics suggests that UST030701-295(T) represents a novel species within the genus Winogradskyella, for which the name Winogradskyella poriferorum sp. nov. is proposed. The type strain is UST030701-295(T) (=NRRL B-41101(T)=JCM 12885(T)).