Characterization of a complex chemosensory signal transduction system which controls twitching motility in Pseudomonas aeruginosa

Abstract

SummaryVirulence of the opportunistic pathogen Pseudomonas aeruginosa involves the coordinate expression of a wide range of virulence factors including type IV pili which are required for colonization of host tissues and are associated with a form of surface translocation termed twitching motility. Twitching motility in P. aeruginosa is controlled by a complex signal transduction pathway which shares many modules in common with chemosensory systems controlling flagella rotation in bacteria and which is composed, in part, of the previously described proteins PilG, PilH, PilI, PilJ and PilK. Here we describe another three components of this pathway: ChpA, ChpB and ChpC, as well as two downstream genes, ChpD and ChpE, which may also be involved. The central component of the pathway, ChpA, possesses nine potential sites of phosphorylation: six histidine-containing phosphotransfer (HPt) domains, two novel serine-and threonine-containing phosphotransfer (SPt, TPt) domains and a CheY-like receiver domain at its Cterminus, and as such represents one of the most complex signalling proteins yet described in nature. We show that the Chp chemosensory system controls twitching motility and type IV pili biogenesis through control of pili assembly and/or retraction as well as expression of the pilin subunit gene pilA . The Chp system is also required for full virulence in a mouse model of acute pneumonia.

Polar Localization of a Soluble Methyl-Accepting Protein ofPseudomonas aeruginosa

“…These results are in agreement with previous studies that indicate that crosstalk does not occur between the different motility systems. For example, a transposon mutation in Pa0411 (located within cluster III) inhibits twitching but not swimming motility, consistent with a role of Pa0411 in twitching motility only (30). We predict that in P. aeruginosa, cross-talk does not occur between the chemoreceptors from different motility systems, a conclusion also reached by studies with R. sphaeroides (18).…”

“…regulation and function of type IV pili and twitching motility (30), and Cluster IV is involved in autoaggregation (4). The function of Cluster II remains unclear, although one of the encoded MCPs (Pa0176; McpB [6], also referred to as Aer-2 [8,10] or TlpG [9]) is involved in aerotaxis (9).…”

Chemotaxis in Rhodobacter sphaeroides Requires an Atypical Histidine Protein Kinase

“…In this report we will call proteins with an identical domain organization to E. coli classic CheAs, whereas chemotaxis proteins containing at least two of the E. coli CheA domains but either lacking some of the other domains or containing additional domains are called atypical CheAs. Atypical CheAs have been found in a range of organisms for example Rhodobacter sphaeroides (15), Myxococcus xanthus (16), and Pseudomonas aeruginosa (17).…”

Global Regulatory Pathways and Cross-talk ControlPseudomonas aeruginosaEnvironmental Lifestyle and Virulence Phenotype

“…The Chp system components are homologous to the E. coli chemotaxis system responsible for controlling flagellar motility (Silversmith, 1999). The Chp system was previously shown to control Tfp production and twitching motility (Darzins, 1997;Whitchurch, 2004). Additionally, the Chp system appears critical for P. aeruginosa virulence, as mutants are attenuated in a Drosophila model of P. aeruginosa infection.…”