Identification of Recombination and Positively Selected Genes in Brucella
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Brucella is a facultative intracellular bacterium belongs to the class alpha proteobacteria. It causes zoonotic disease brucellosis to wide range of animals. Brucella species are highly conserved in nucleotide level. Here, we employed a comparative genomics approach to examine the role of homologous recombination and positive selection in the evolution of Brucella. For the analysis, we have selected 19 complete genomes from 8 species of Brucella. Among the 1599 core genome predicted, 24 genes were showing signals of recombination but no significant breakpoint was found. The analysis revealed that recombination events are less frequent and the impact of recombination occurred is negligible on the evolution of Brucella. This leads to the view that Brucella is clonally evolved. On other hand, 56 genes (3.5 % of core genome) were showing signals of positive selection. Results suggest that natural selection plays an important role in the evolution of Brucella. Some of the genes that are responsible for the pathogenesis of Brucella were found positively selected, presumably due to their role in avoidance of the host immune system.
KeywordsBrucella Recombination Positive selection Evolution
This work was supported by the Department of Biotechnology, New Delhi through DBT-Network Project on Brucellosis. The UGC-CAS, CEGS, NRCBS, DBT-IPLS, DST-PURSE Programs of School of Biological Sciences, Madurai Kamaraj University is gratefully acknowledged.
Compliance with Ethical Standards
The authors have declared that no competing interest exists.
- 12.Halling SM, Peterson-Burch BD, Bricker BJ, Zuerner RL, Qing Z, Li LL, Kapur V, Alt DP, Olsen SC (2005) Completion of the genome sequence of Brucella abortus and comparison to the highly similar genomes of Brucella melitensis and Brucella suis. J Bacteriol 187:2715–2726. doi: 10.1128/JB.187.8.2715-2726.2005 PubMedCentralCrossRefPubMedGoogle Scholar
- 19.Kennemann L, Didelot X, Aebischer T, Kuhn S, Drescher B, Droege M, Reinhardtf R, Correag P, Meyerc TF, Josenhansa C, Falushh D, Suerbaum S (2011) Helicobacter pylori genome evolution during human infection. Proc Natl Acad Sci USA 108:5033–5038. doi: 10.1073/pnas.1018444108 PubMedCentralCrossRefPubMedGoogle Scholar
- 20.Silva C, Vinuesa P, Eguiarte LE, Souza V, Martinez-Romero E (2005) Evolutionary genetics and biogeographic structure of Rhizobium gallicum sensu lato, a widely distributed bacterial symbiont of diverse legumes. Mol Ecol 14:4033–4050. doi: 10.1111/j.1365-294X.2005.02721.x CrossRefPubMedGoogle Scholar
- 25.Hornback ML, Roop RM (2006) The Brucella abortus xthA-1 gene product participates in base excision repair and resistance to oxidative killing but is not required for wild-type virulence in the mouse model. J Bacteriol 188:1295–1300. doi: 10.1128/JB.188.4.1295-1300.2006 PubMedCentralCrossRefPubMedGoogle Scholar
- 28.Tsolis RM, Seshadri R, Santos RL, Sangari FJ, Lobo JMG, de Jong MF, Ren Q, Myers G, Brinkac LM, Nelson WC, Deboy RT, Angiuoli S, Khouri H, Dimitrov G, Robinson JR, Mulligan S, Walker RL, Elzer PE, Hassan KA, Paulsen IT (2009) Genome degradation in Brucella ovis corresponds with narrowing of its host range and tissue tropism. PLoS ONE 4:e5519. doi: 10.1371/journal.pone.0005519 PubMedCentralCrossRefPubMedGoogle Scholar