Rhodobacter capsulatus DprA is essential for RecA‐mediated gene transfer agent (RcGTA) recipient capability regulated by quorum‐sensing and the CtrA response regulator. Issue 6 (21st May 2014)

• Record Type: Journal Article
• Authors: Brimacombe, Cedric A.; Ding, Hao; Beatty, J. Thomas
• Is Part Of: Molecular microbiology. Volume 92:Issue 6(2014)
• Page Start: 1260
• Page End: 1278
• Publication Date: 2014-05-21
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.12628
• Languages: English
• ISSNs: 0950-382X

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>Gene transfer agents (GTAs) are genetic exchange elements that resemble small DNA bacteriophages that transfer random pieces of the producing cell's genome to recipient cells. The best‐studied GTA is that of <italic>R</italic><italic>hodobacter capsulatus</italic>, termed RcGTA. We discovered that the putative response regulator CtrA, which is essential for RcGTA production, is required for RcGTA‐mediated gene acquisition, and confirmed that a RecA homologue is required. It was also discovered that a DprA (DNA‐protecting protein A) homologue is essential for RcGTA‐mediated gene acquisition, and that <italic>dprA</italic> expression is induced by <italic>gtaI</italic>‐dependent quorum‐sensing and non‐phosphorylated CtrA. Modelling of the <italic>R</italic><italic>. capsulatus</italic> DprA structure indicated the presence of a C‐terminal region that resembles a dsDNA‐binding protein domain. Purified His‐tagged <italic>R</italic><italic>. capsulatus</italic> DprA protein bound to both single‐stranded (ss)DNA and double‐stranded (ds)DNA, but with a greater affinity for ssDNA. Additionally, DprA protected dsDNA from endonuclease digestion, and increased the rate of nucleation of <italic>E</italic><italic>scherichia coli</italic> RecA onto ssDNA. Single‐cell expression analyses revealed that <italic>dprA</italic> is expressed in the majority of cells throughout a population. Overall, the results suggest that incorporation of RcGTA DNA into the recipient cell genome proceeds through a homologous recombination pathway resembling DNA recombination in natural transformation.</p> </abstract>