RESUMEN

Synthetic biology (SynBio) is a rapidly advancing multidisciplinary field in which South American countries such as Chile, Argentina, and Brazil have made notable contributions and have established leadership positions in the region. In recent years, efforts have strengthened SynBio in the rest of the countries, and although progress is significant, growth has not matched that of the aforementioned countries. Initiatives such as iGEM and TECNOx have introduced students and researchers from various countries to the foundations of SynBio. Several factors have hindered progress in the field, including scarce funding from both public and private sources for synthetic biology projects, an underdeveloped biotech industry, and a lack of policies to promote bio-innovation. However, open science initiatives such as the DIY movement and OSHW have helped to alleviate some of these challenges. Similarly, the abundance of natural resources and biodiversity make South America an attractive location to invest in and develop SynBio projects.

RESUMEN

Here, we present the draft genome sequence of strain UYCP14C, a rhizobium isolated from Calliandra parvifolia nodules. The assembled genome size was around 9.8 million bp, containing 9,031 predicted protein-coding sequences, including several symbiotic and nitrogen fixation genes. UYCP14C appears to be a novel species of the plant growth-promoting Paraburkholderia genus.

RESUMEN

The presence of some sugars (e.g. glucose) downregulates the activity of the Pu promoter of plasmid pWW0 of Pseudomonas putida mt-2, which drives the upper TOL operon for biodegradation of m-xylene. Genetic evidence produced 20 years ago documented an effect of the EIIANtr (PtsN) protein of the nitrogen-related phosphoenolpyruvate-dependent phosphotransferase system (PTSNtr ) in such a C-source control of Pu activity. In this study, we have exploited the wealth of recent information on the PTS of P. putida as well as transcriptomic data available in the last few years on this bacterium to revisit this question - and the role of EIIANtr as such. To this end, we examined Pu output under physiological conditions known to either phosphorylate PTS proteins to saturation or to deplete them altogether from high-energy phosphate. The results showed that Pu activity is checked by EIIANtr regardless of its phosphorylation state. However, such inhibition is intensified during growth on glucose (which correlates with more phosphate-free EIIANtr ) and partially relieved in fructose, which triggers phosphorylation of PTS proteins. These data explain former inconsistencies on the Pu-PTSNtr interplay and provides a better understanding of the metabolic and regulatory retroactivity between the TOL plasmid and its host metabolism.

Asunto(s)

Proteínas Bacterianas/metabolismo , Carbono/metabolismo , Sistema de Fosfotransferasa de Azúcar del Fosfoenolpiruvato/metabolismo , Regiones Promotoras Genéticas , Pseudomonas putida/metabolismo , Regulación Bacteriana de la Expresión Génica/efectos de los fármacos , Glucosa/metabolismo , Nitrógeno/metabolismo , Operón , Fosforilación , Plásmidos , Pseudomonas putida/genética , Xilenos/metabolismo

RESUMEN

Herbaspirillum seropedicae Z67 is a nitrogen-fixing endophyte that colonizes many important crops. Like in almost all organisms, vital cellular processes of this endophyte are iron dependent. In order to efficiently acquire iron to fulfill its requirements, this bacterium produces the siderophores serobactins. However, the presence in its genome of many others iron acquisition genes suggests that serobactins are not the only strategy used by H. seropedicae to overcome metal deficiency. The aim of this work was to identify genes and proteins differentially expressed by cells growing in low iron conditions in order to describe H. seropedicae response to iron limitation stress. For this purpose, and by using a transcriptomic approach, we searched and identified a set of genes up-regulated when iron was scarce. One of them, Hsero_2337, codes for a TonB-dependent transporter/transducer present in the serobactins biosynthesis genomic locus, with an unknown function. Another TonB-dependent receptor, the one encoded by Hsero_1277, and an inner membrane ferrous iron permease, coded by Hsero_2720, were also detected. By using a proteomic approach focused in membrane proteins, we identified the specific receptor for iron-serobactin internalization SbtR and two non-characterized TonB-dependent receptors (coded by genes Hsero_1277 and Hsero_3255). We constructed mutants on some of the identified genes and characterized them by in vitro growth, biofilm formation, and interaction with rice plants. Characterization of mutants in gene Hsero_2337 showed that the TonB-dependent receptor coded by this gene has a regulatory role in the biosynthesis of serobactins, probably by interacting with the alternative sigma factor PfrI, coded by gene Hsero_2338. Plant colonization of the mutant strains was not affected, since the mutant strain normally colonize the root and aerial part of rice plants. These results suggest that the strategies used by H. seropedicae to acquire iron inside plants are far more diverse than the ones characterized in this work. In vivo expression studies or colonization competition experiments between the different mutant strains could help us in future works to determine the relative importance of the different iron acquisition systems in the interaction of H. seropedicae with rice plants.

RESUMEN

We present the draft genome of Cupriavidus UYMMa02A, a rhizobium strain isolated from root nodules of Mimosa magentea The assembly has approximately 8.1 million bp with an average G+C of 64.1%. Symbiotic and metal-resistance genes were identified. The study of this genome will contribute to the understanding of rhizobial evolution.

RESUMEN

UNLABELLED: The large legume genus Mimosa is known to be associated with both alphaproteobacterial and betaproteobacterial symbionts, depending on environment and plant taxonomy, e.g., Brazilian species are preferentially nodulated by Burkholderia, whereas those in Mexico are associated with alphaproteobacterial symbionts. Little is known, however, about the symbiotic preferences of Mimosa spp. at the southern subtropical limits of the genus. In the present study, rhizobia were isolated from field-collected nodules from Mimosa species that are native to a region in southern Uruguay. Phylogenetic analyses of sequences of the 16S rRNA, recA, and gyrB core genome and the nifH and nodA symbiosis-essential loci confirmed that all the isolates belonged to the genus Cupriavidus However, none were in the well-described symbiotic species C. taiwanensis, but instead they were closely related to other species, such as C. necator, and to species not previously known to be symbiotic (or diazotrophic), such as C. basilensis and C. pinatubonensis Selection of these novel Cupriavidus symbionts by Uruguayan Mimosa spp. is most likely due to their geographical separation from their Brazilian cousins and to the characteristics of the soils in which they were found. IMPORTANCE: With the aim of exploring the diversity of rhizobia associated with native Mimosa species, symbionts were isolated from root nodules on five Mimosa species that are native to a region in southern Uruguay, Sierra del Abra de Zabaleta. In contrast to data obtained in the major centers of diversification of the genus Mimosa, Brazil and Mexico, where it is mainly associated with Burkholderia and Rhizobium/Ensifer, respectively, the present study has shown that all the isolated symbiotic bacteria belonged to the genus Cupriavidus Interestingly, none of nodules contained bacteria belonging to the well-described symbiotic species C. taiwanensis, but instead they were related to other Cupriavidus species such as C. necator and C. pinatubonensis These data suggest the existence of a higher diversity within beta-rhizobial Cupriavidus than was previously suspected, and that Mimosa spp. from Sierra del Abra de Zabaleta, may be natural reservoirs for novel rhizobia.

Asunto(s)

Cupriavidus/clasificación , Cupriavidus/aislamiento & purificación , Mimosa/microbiología , Raíces de Plantas/microbiología , Proteínas Bacterianas/genética , Análisis por Conglomerados , Cupriavidus/genética , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Filogenia , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Uruguay

RESUMEN

Among the leguminous trees native to Uruguay, Parapiptadenia rigida (Angico), a Mimosoideae legume, is one of the most promising species for agroforestry. Like many other legumes, it is able to establish symbiotic associations with rhizobia and belongs to the group known as nitrogen-fixing trees, which are major components of agroforestry systems. Information about rhizobial symbionts for this genus is scarce, and thus, the aim of this work was to identify and characterize rhizobia associated with P. rigida. A collection of Angico-nodulating isolates was obtained, and 47 isolates were selected for genetic studies. According to enterobacterial repetitive intergenic consensus PCR patterns and restriction fragment length polymorphism analysis of their nifH and 16S rRNA genes, the isolates could be grouped into seven genotypes, including the genera Burkholderia, Cupriavidus, and Rhizobium, among which the Burkholderia genotypes were the predominant group. Phylogenetic studies of nifH, nodA, and nodC sequences from the Burkholderia and the Cupriavidus isolates indicated a close relationship of these genes with those from betaproteobacterial rhizobia (beta-rhizobia) rather than from alphaproteobacterial rhizobia (alpha-rhizobia). In addition, nodulation assays with representative isolates showed that while the Cupriavidus isolates were able to effectively nodulate Mimosa pudica, the Burkholderia isolates produced white and ineffective nodules on this host.

Asunto(s)

Burkholderia/fisiología , Cupriavidus/fisiología , Fabaceae/microbiología , Nodulación de la Raíz de la Planta , Raíces de Plantas/microbiología , Rhizobium/fisiología , Burkholderia/clasificación , Burkholderia/genética , Burkholderia/aislamiento & purificación , Análisis por Conglomerados , Cupriavidus/clasificación , Cupriavidus/genética , Cupriavidus/aislamiento & purificación , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Genotipo , Mimosa/microbiología , Datos de Secuencia Molecular , Tipificación Molecular , Fijación del Nitrógeno , Oxidorreductasas/genética , Filogenia , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de Restricción , ARN Ribosómico 16S/genética , Rhizobium/clasificación , Rhizobium/genética , Rhizobium/aislamiento & purificación , Análisis de Secuencia de ADN , Uruguay

RESUMEN

In Sinorhizobium meliloti, the Mur(Sm) protein, a homologue of the ferric uptake regulator (Fur), mediates manganese-dependent regulation of the MntABCD manganese uptake system. In this study, we analyzed Mur(Sm) binding to the promoter region of the S. meliloti mntA gene. We demonstrated that Mur(Sm) protein binds with high affinity to the promoter region of mntA gene in a manganese-responsive manner. Moreover, the results presented here indicate that two monomers, or one dimer, of Mur(Sm) binds the DNA. The binding region was identified by DNase I footprinting analysis and covers a region of about 30 bp long that contains a palindromic sequence. The Mur(Sm) binding site, present in the mntA promoter region, is similar to a Fur box; however, manganese-activated Mur(Sm) binds a canonical Fur box with very low affinity. Furthermore, the data obtained indicate that Mur(Sm) responds to physiological concentrations of manganese.

Asunto(s)

Transportadoras de Casetes de Unión a ATP/química , Proteínas Bacterianas/metabolismo , Regulación Bacteriana de la Expresión Génica , Manganeso/metabolismo , Regiones Promotoras Genéticas , Proteínas Represoras/metabolismo , Sinorhizobium meliloti/metabolismo , Transportadoras de Casetes de Unión a ATP/genética , Transportadoras de Casetes de Unión a ATP/metabolismo , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Secuencia de Bases , Sitios de Unión , Datos de Secuencia Molecular , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Represoras/química , Proteínas Represoras/genética , Sinorhizobium meliloti/genética

RESUMEN

Herbaspirillum seropedicae Z67 is a nitrogen-fixing bacterium able to colonize the rhizosphere and the interior of several plants. As iron is a key element for nitrogen fixation, we examined the response of this microorganism to iron deficiency under nitrogen fixing conditions. We identified a H. seropedicae exbD gene that was induced in response to iron limitation and is involved in iron homeostasis. We found that an exbD mutant grown in iron-chelated medium is unable to fix nitrogen. Moreover, we provide evidence that expression of the nifH and nifA genes is iron dependent in a H. seropedicae genetic background.

Asunto(s)

Proteínas Bacterianas/metabolismo , Herbaspirillum/metabolismo , Hierro/metabolismo , Nitrogenasa/metabolismo , Oxidorreductasas/metabolismo , Factores de Transcripción/metabolismo , Proteínas Bacterianas/genética , Regulación Bacteriana de la Expresión Génica , Herbaspirillum/enzimología , Herbaspirillum/genética , Mutación , Fijación del Nitrógeno , Nitrogenasa/genética , Oxidorreductasas/genética , Factores de Transcripción/genética

RESUMEN

Fur is a transcriptional regulator involved in iron-dependent control of gene expression in many bacteria. In this work we analyzed the phenotype of a fur mutant in Sinorhizobium meliloti, an alpha-proteobacterium that fixes N(2) in association with host plants. We demonstrated that some functions involved in high-affinity iron transport, siderophore production, and iron-regulated outer membrane protein expression respond to iron in a Fur-independent manner. However, manganese-dependent expression of the MntABCD manganese transport system was lost in a fur strain as discerned by constitutive expression of a mntA::gfp fusion reporter gene in the mutant. Thus, Fur directly or indirectly regulates a manganese-dependent function. The data indicate a novel function for a bacterial Fur protein in mediating manganese-dependent regulation of gene expression.

Asunto(s)

Transportadoras de Casetes de Unión a ATP/genética , Proteínas Bacterianas/fisiología , Regulación Bacteriana de la Expresión Génica , Manganeso/metabolismo , Proteínas Represoras/fisiología , Sinorhizobium meliloti/genética , Proteínas de la Membrana Bacteriana Externa/genética , Hierro/metabolismo , Operón , Sideróforos/biosíntesis , Simbiosis

RESUMEN

Two transposon-induced mutants of Sinorhizobium meliloti 242 were isolated based on their inability to grow on rich medium supplemented with the metal chelator ethylenediamine di-o-hydroxyphenylacetic acid (EDDHA) and either heme-compounds or siderophores as iron sources. Tagged loci of these mutants were identified as sit B and sit D genes. These genes encode components of an ABC (ATP-binding cassette) metal-type permease in several Gram-negative bacteria. In this work, the phenotypes of these two mutants were compared with those of two siderophore-mediated iron transport mutants. The results strongly implicate a role of the sit genes in manganese acquisition when this metal is limiting in S. meliloti.

Asunto(s)

Manganeso/farmacología , Sinorhizobium meliloti/crecimiento & desarrollo , Sinorhizobium meliloti/metabolismo , Transportadoras de Casetes de Unión a ATP/genética , Transportadoras de Casetes de Unión a ATP/metabolismo , Elementos Transponibles de ADN , Etilenodiaminas/farmacología , Genes Bacterianos/genética , Hierro/metabolismo , Quelantes del Hierro/farmacología , Medicago sativa/crecimiento & desarrollo , Medicago sativa/microbiología , Mutación , Análisis de Secuencia de ADN , Sideróforos/genética , Sideróforos/metabolismo , Sinorhizobium meliloti/genética , Simbiosis

RESUMEN

Rhizobia are soil bacteria that are able to establish symbiotic associations with leguminous hosts. In iron-limited environments these bacteria can use iron present in heme or heme compounds (hemoglobin, leghemoglobin). Here we report the presence in Sinorhizobium meliloti of an iron-regulated outer membrane protein that is able to bind hemin but not hemoglobin. Protein assignment was done by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Tryptic peptides correlated with the mass measurements obtained accounted for 54% of the translated sequence of a putative heme receptor gene present in the chromosome of S. meliloti 1021. The results which we obtained suggest that this protein (designated ShmR for Sinorhizobium heme receptor) is involved in high-affinity heme-mediated iron transport.

Asunto(s)

Proteínas de la Membrana Bacteriana Externa/análisis , Proteínas Portadoras , Hemina/metabolismo , Hierro/metabolismo , Sinorhizobium meliloti/química , Secuencia de Aminoácidos , Proteínas de la Membrana Bacteriana Externa/química , Proteínas de la Membrana Bacteriana Externa/metabolismo , Proteínas Bacterianas/metabolismo , Hemo/metabolismo , Proteínas de la Membrana/metabolismo , Datos de Secuencia Molecular , Sinorhizobium meliloti/metabolismo , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción