Distribution of Genes Encoding Nucleoid-Associated Protein Homologs in Plasmids

Abstract

Bacterial nucleoid-associated proteins (NAPs) form nucleoprotein complexes and influence the expression of genes. Recent studies have shown that some plasmids carry genes encoding NAP homologs, which play important roles in transcriptional regulation networks between plasmids and host chromosomes. In this study, we determined the distributions of the well-known NAPs Fis, H-NS, HU, IHF, and Lrp and the newly found NAPs MvaT and NdpA among the whole-sequenced 1382 plasmids found in Gram-negative bacteria. Comparisons between NAP distributions and plasmid features (size, G+C content, and putative transferability) were also performed. We found that larger plasmids frequently have NAP gene homologs. Plasmids with H-NS gene homologs had less G+C content. It should be noted that plasmids with the NAP gene homolog also carried the relaxase gene involved in the conjugative transfer of plasmids more frequently than did those without the NAP gene homolog, implying that plasmid-encoded NAP homologs positively contribute to transmissible plasmids.

Bacterial Hha-like proteins facilitate incorporation of horizontally transferred DNA

“…Interestingly, 55% of those plasmids encoding an H-NS paralogue also encode an Hha paralogue. In contrast, Hha paralogues were encoded in only 5% of all the plasmids analyzed [44]. This further supports the close relationship between H-NS and Hha-like proteins.…”

“…An additional distinctive feature of both families of proteins is that several plasmids also code for these proteins [44]. Interestingly, 55% of those plasmids encoding an H-NS paralogue also encode an Hha paralogue.…”

A Three-protein Charge Zipper Stabilizes a Complex Modulating Bacterial Gene Silencing

“…Hha/YmoA bind to the nucleoid-associated protein H-NS (7), enhance its capacity to silence newly acquired genes, and facilitate the smooth integration of foreign genes in the existing genome (8,9). The key role of members of the Hha/ YmoA family in enterobacteria is supported by their conservation in obligate endosymbionts (10) and their presence in conjugative plasmids (11). Hha is also directly involved in the formation and dispersal of biofilms, a microbial life-style that is responsible of many chronic infections and is associated with increased antibiotic tolerance and with resistance dissemination (12)(13)(14).…”

Characterization of the Nucleoid-associated Protein YejK

“…Little is known about this protein absent the initial publication. It has also been referred to as NdpA (18). Analysis against the protein databases did not uncover either any conserved domains or known motifs.…”

“…Analysis against the protein databases did not uncover either any conserved domains or known motifs. Nevertheless, it is widely distributed in bacteria and the gene is present on some large plasmid DNAs as well (18). Because this was the only NAP identified in the two-hybrid screen, we characterized the protein and the effect on E. coli of deleting the gene.…”