Regulation of gene expression during swarmer cell differentiation inProteus mirabilis

Abstract

The gram-negative bacterium Proteus mirabilis can exist in either of two cell types, a vegetative cell characterized as a short rod and a highly elongated and hyperflagellated swarmer cell. This differentiation is triggered by growth on solid surfaces and multiple inputs are sensed by the cell to initiate the differentiation process. These include the inhibition of flagellar rotation, the accumulation of extracellular putrescine and O-antigen interactions with a surface. A key event in the differentiation process is the upregulation of FlhD(2)C(2), which activates the flagellar regulon and additional genes required for differentiation. There are a number of genes that influence FlhD(2)C(2) expression and the function of these genes, if known, will be discussed in this review. Additional genes that have been shown to regulate gene expression during swarming will also be reviewed. Although P. mirabilis represents an excellent system to study microbial differentiation, it is largely understudied relative to other systems. Therefore, this review will also discuss some of the unanswered questions that are central to understanding this process in P. mirabilis.

Proteus sp. – an opportunistic bacterial pathogen – classification, swarming growth, clinical significance and virulence factors

“…It results in the formation of characteristic rings of bacterial growth on the agar plate ( fig. 1) (VERSTRAETEN et al 2008, MORGENSTEIN et al 2010, RÓŻALSKI & STĄCZEK 2010.…”

“…Lipopolysaccharide (LPS), a surface component of these bacteria, seems to be important in the swarming phenomenon, however, its exact role has not been described. Mutation in the wzz region encoding O-antigen chain, as well as in genes waaD and waaC required for the core region of LPS are impaired in swarming growth (MORGENSTEIN et al 2010). Swarmer cells translocation is facilitated by an extracellular acidic polysaccharide designated as Cmf (colony migration factor), which acts as a lubricant, reducing surface friction (GYGI et al 1995).…”

Diclofenac inhibits virulence of Proteus mirabilis isolated from diabetic foot ulcer

“…It showed that sub-inhibitory concentrations of diclofenac inhibited the swarming and swimming motilities significantly which may affect the infection spread which may influence the pathogenesis as a consequence. Several factors participated in the regulation of swarming motility including the up-regulator of flagellar master operon (Umo) proteins and other factors reviewed elsewhere (Morgenstein et al, 2010). Moreover, all flagellum-related genes are arranged within a single 53.3-kb locus (Pearson et al, 2008), which may indicate the significance of inhibition of the transcriptional regulator on motility.…”

“…Proteus is a causative agent of wide range of infections; the potential of its virulence is not only due to production of several extracellular enzymes, but also due to inherent capability of pretrichrous flagellar translocation and its biofilm formation capability (Morgenstein et al, 2010;Armbruster and Mobley, 2012). In the last decades, resistance development is one of the serious emerging problems and it is owed to genotypic and/or phenotypic modifications.…”

“…For instance, 94 Kb ICE PM1 mobile pathogenicity island of P. mirabilis is present with up to 100% sequence identity for some genes in several Proteus species, which indicate DNA transfer between these species (Flannery et al, 2009). The virulence factors of P. mirabilis are widely diverse, adhesive fimbria, flagella swarming motility and production of toxins as haemolysin and extracellular enzymes as protease and urease all are working cooperatively on pathogenesis enhancement (Jacobsen et al, 2008;Morgenstein et al, 2010;Armbruster and Mobley, 2012). The biofilm formation by P. mirabilis constitutes an additive obstacle in antibiotic treatment of infections and its prevention is considered as an aim (Jacobsen et al, 2008;Zhao and Hu, 2013).…”