Transcriptional Profiling of ParA and ParB Mutants in Actively Dividing Cells of an Opportunistic Human Pathogen Pseudomonas aeruginosa

Abstract

Accurate chromosome segregation to progeny cells is a fundamental process ensuring proper inheritance of genetic material. In bacteria with simple cell cycle, chromosome segregation follows replication initiation since duplicated oriC domains start segregating to opposite halves of the cell soon after they are made. ParA and ParB proteins together with specific DNA sequences are parts of the segregation machinery. ParA and ParB proteins in Pseudomonas aeruginosa are important for optimal growth, nucleoid segregation, cell division and motility. Comparative transcriptome analysis of parA null and parB null mutants versus parental P. aeruginosa PAO1161 strain demonstrated global changes in gene expression pattern in logarithmically growing planktonic cultures. The set of genes similarly affected in both mutant strains is designated Par regulon and comprises 536 genes. The Par regulon includes genes controlled by two sigma factors (RpoN and PvdS) as well as known and putative transcriptional regulators. In the absence of Par proteins, a large number of genes from RpoS regulon is induced, reflecting the need for slowing down the cell growth rate and decelerating the metabolic processes. Changes in the expression profiles of genes involved in c-di-GMP turnover point out the role of this effector in such signal transmission. Microarray data for chosen genes were confirmed by RT-qPCR analysis. The promoter regions of selected genes were cloned upstream of the promoter-less lacZ gene and analyzed in the heterologous host E. coliΔlac. Regulation by ParA and ParB of P. aeruginosa was confirmed for some of the tested promoters. Our data demonstrate that ParA and ParB besides their role in accurate chromosome segregation may act as modulators of genes expression. Directly or indirectly, Par proteins are part of the wider regulatory network in P. aeruginosa linking the process of chromosome segregation with the cell growth, division and motility.

Increased ParB level affects expression of stress response, adaptation and virulence operons and potentiates repression of promoters adjacent to the high affinity binding sites parS3 and parS4 in Pseudomonas aeruginosa

“…aeruginosa relative to the wild type PAO1161 (WT) cells [39]. To complement this study, here we analysed the transcriptome of ParB -overproducing cells.…”

Comparative Genomics Revealed Multiple Helicobacter pylori Genes Associated with Biofilm Formation In Vitro

“…In P . aeruginosa , par mutants have been observed to be impaired in motility suggesting a direct or indirect role of Par proteins in regulation of these processes [33]. ParA/ParB family of proteins together with the centromere-like DNA sequence parS is involved in chromosome and plasmid partitioning during bacterial cell division.…”

“…In the absence of ParB, ParA is most probably in its dimeric state bound with ATP proficient to bind non-specifically to DNA [34]. Furthermore, par mutation also induced genes induced involve in c-di-GMP turnover and signaling [33]. Cyclic-di-GMP (cyclic diguanylate) is an important messenger ubiquitous in bacterial cells controlling various processes, e.g.…”

Chromosome Segregation in <b><i>Vibrio cholerae</i></b>

“…The regulation of chromosomal par genes are generally not known except in some isolated cases [Casart et al, 2008]. In plasmids, the parAB genes form an autoregulated operon, but this was not the case when chromosomal par genes were tested in P. aeruginosa and in V. cholerae for chr1 [Baek et al, 2014; Bartosik et al, 2014]. Whether and how par genes of chr1 are regulated remains to be determined.…”