Discovery of a new family of relaxases in Firmicutes bacteria

• DOI: 10.1371/journal.pgen.1006586
• Publication Date: 2017-02-16T21:09:36Z
• Authors: Gayetri Ramachandran; Andrés Miguel-Arr...; David Abia; Praveen K. Singh; Isidro Crespo; César Gago-Córdoba; Jian An Hao; Juan Roman Luque-...; Carlos Alfonso; Ling J. Wu; D. Roeland Boer; Wilfried J. J. Me...
• Keywords: Horizontal Gene Transfer; Bacterial Genetics

Antibiotic resistance is a serious global problem. genes (ARG), which are widespread in environmental bacteria, can be transferred to pathogenic bacteria via horizontal gene transfer (HGT). Gut microbiomes especially apt for the emergence and dissemination of ARG. Conjugation HGT route that predominantly responsible spread Little known about conjugative elements Gram-positive including those phylum Firmicutes, abundantly present gut microbiomes. A critical step conjugation process relaxase-mediated site- strand-specific nick oriT region element. This generates single-stranded DNA molecule from donor recipient cell connecting channel. Here we identified characterized relaxosome components relaxase plasmid pLS20 Firmicute Bacillus subtilis. We show gene, named relLS20, essential conjugation, it function trans provide evidence Tyr26 constitutes active site residue. In vivo vitro analyses revealed located far upstream within on template strand genes. Surprisingly, RelLS20 shows very limited similarity relaxases. However, more than 800 no had been attributed so predicted encode proteins showing significant RelLS20. Interestingly, these putative relaxases encoded almost exclusively Firmicutes bacteria. Thus, prototype new family The identification this novel will have an important impact different aspects future research field general, specifically microbiome research.