Dataset Information

Cloning of the hsp70 (dnaK) genes from Rhizobium meliloti and Pseudomonas cepacia: phylogenetic analyses of mitochondrial origin based on a highly conserved protein sequence.

ABSTRACT: The genes for hsp70 (or dnaK) have been cloned and sequenced from Rhizobium meliloti and Pseudomonas cepacia, two bacterial species belonging to the alpha- and beta-subdivisions of gram-negative proteobacteria, respectively. On the basis of global alignment of HSP70 proteins, several sequence signatures have been identified that are distinctive of mitochondrial homologs and gram-negative proteobacteria on the one hand and the chloroplasts and cyanobacteria on the other. Detailed phylogenetic analyses of HSP70 sequences from various eubacteria and eukaryotic organellar and cytosolic homologs support the inference regarding the origin of mitochondria from a member of the alpha-proteobacteria and of chloroplasts from cyanobacteria. The analysis presented here also suggests a monophyletic origin of the mitochondrial homologs.

SUBMITTER: Falah M

PROVIDER: S-EPMC197237 | biostudies-other | 1994 Dec

REPOSITORIES: biostudies-other

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Cloning of the hsp70 (dnaK) genes from Rhizobium meliloti and Pseudomonas cepacia: phylogenetic analyses of mitochondrial origin based on a highly conserved protein sequence.

Falah M M Gupta R S RS

Journal of bacteriology 19941201 24

The genes for hsp70 (or dnaK) have been cloned and sequenced from Rhizobium meliloti and Pseudomonas cepacia, two bacterial species belonging to the alpha- and beta-subdivisions of gram-negative proteobacteria, respectively. On the basis of global alignment of HSP70 proteins, several sequence signatures have been identified that are distinctive of mitochondrial homologs and gram-negative proteobacteria on the one hand and the chloroplasts and cyanobacteria on the other. Detailed phylogenetic ana ...[more]

PMID: 7528198

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Project description:Genome-wide association studies (GWAS) can identify genetic variants responsible for naturally occurring and quantitative phenotypic variation. Association studies therefore provide a powerful complement to approaches that rely on de novo mutations for characterizing gene function. Although bacteria should be amenable to GWAS, few GWAS have been conducted on bacteria, and the extent to which nonindependence among genomic variants (e.g., linkage disequilibrium [LD]) and the genetic architecture of phenotypic traits will affect GWAS performance is unclear. We apply association analyses to identify candidate genes underlying variation in 20 biochemical, growth, and symbiotic phenotypes among 153 strains of Ensifer meliloti For 11 traits, we find genotype-phenotype associations that are stronger than expected by chance, with the candidates in relatively small linkage groups, indicating that LD does not preclude resolving association candidates to relatively small genomic regions. The significant candidates show an enrichment for nucleotide polymorphisms (SNPs) over gene presence-absence variation (PAV), and for five traits, candidates are enriched in large linkage groups, a possible signature of epistasis. Many of the variants most strongly associated with symbiosis phenotypes were in genes previously identified as being involved in nitrogen fixation or nodulation. For other traits, apparently strong associations were not stronger than the range of associations detected in permuted data. In sum, our data show that GWAS in bacteria may be a powerful tool for characterizing genetic architecture and identifying genes responsible for phenotypic variation. However, careful evaluation of candidates is necessary to avoid false signals of association.IMPORTANCE Genome-wide association analyses are a powerful approach for identifying gene function. These analyses are becoming commonplace in studies of humans, domesticated animals, and crop plants but have rarely been conducted in bacteria. We applied association analyses to 20 traits measured in Ensifer meliloti, an agriculturally and ecologically important bacterium because it fixes nitrogen when in symbiosis with leguminous plants. We identified candidate alleles and gene presence-absence variants underlying variation in symbiosis traits, antibiotic resistance, and use of various carbon sources; some of these candidates are in genes previously known to affect these traits whereas others were in genes that have not been well characterized. Our results point to the potential power of association analyses in bacteria, but also to the need to carefully evaluate the potential for false associations.

Dataset Information

Cloning of the hsp70 (dnaK) genes from Rhizobium meliloti and Pseudomonas cepacia: phylogenetic analyses of mitochondrial origin based on a highly conserved protein sequence.

Publications

Cloning of the hsp70 (dnaK) genes from Rhizobium meliloti and Pseudomonas cepacia: phylogenetic analyses of mitochondrial origin based on a highly conserved protein sequence.

Similar Datasets

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