Identification of flgZ as a Flagellar Gene Encoding a PilZ Domain Protein That Regulates Swimming Motility and Biofilm Formation in Pseudomonas

Francisco Martínez-Granero,Rafael Rivilla,Irene Baena,Miguel Redondo-Nieto,Ana Navazo,Marta Martín,Elena González De Heredia,Emma Barahona,Irene Martín-Martín,Vasu D Appanna

doi:10.1371/journal.pone.0087608

Francisco Martínez-Granero, Rafael Rivilla + Show 8 more

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https://doi.org/10.1371/journal.pone.0087608

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Journal: PloS one	Publication Date: Feb 4, 2014
Citations: 101	License type: CC BY 4.0

Affiliation: Autonomous University of Madrid

Abstract

Diguanylate cyclase and phosphodiesterase enzymatic activities control c-di-GMP levels modulating planktonic versus sessile lifestyle behavior in bacteria. The PilZ domain is described as a sensor of c-di-GMP intracellular levels and the proteins containing a PilZ domain represent the best studied class of c-di-GMP receptors forming part of the c-di-GMP signaling cascade. In P. fluorescens F113 we have found two diguanylate cyclases (WspR, SadC) and one phosphodiesterase (BifA) implicated in regulation of swimming motility and biofilm formation. Here we identify a flgZ gene located in a flagellar operon encoding a protein that contains a PilZ domain. Moreover, we show that FlgZ subcellular localization depends on the c-di-GMP intracellular levels. The overexpression analysis of flgZ in P. fluorescens F113 and P. putida KT2440 backgrounds reveal a participation of FlgZ in Pseudomonas swimming motility regulation. Besides, the epistasis of flgZ over wspR and bifA clearly shows that c-di-GMP intracellular levels produced by the enzymatic activity of the diguanylate cyclase WspR and the phosphodiesterase BifA regulates biofilm formation through FlgZ.

Highlights

The turn-over of the messenger molecule c-di-GMP modulates lifestyles in a diversity of bacteria. c-di-GMP levels have been shown to define the planktonic/sessile behavior of bacterial cells, reviewed in [1]
The flgZ gene encodes a protein belonging to the orthologous group COG5581 which contains the highly conserved PilZ domain in the C-terminus and a weakly conserved YcgR domain in the N-terminus (Fig. 1B), showing weak homology with the YcgR protein of Enterobacteria, a PilZ domain protein that has been shown to downregulate motility acting on the flagellar motor in response to the levels of cdi-GMP produced by several diguanylate cyclases [22,23,24]
The PilZ domain of flgZ shows homology with a similar domain in the DgrA protein of Caulobacter [25] that has been shown to downregulate swimming motility (Fig. 1B)

Summary

Introduction

The turn-over of the messenger molecule c-di-GMP modulates lifestyles in a diversity of bacteria. c-di-GMP levels have been shown to define the planktonic/sessile behavior of bacterial cells, reviewed in [1]. Genes encoding proteins with these domains are ubiquitous in bacterial genomes and are frequently present in large numbers in a single genome Proteins containing both GGDEF and EAL domains are frequent and in some cases, one of the domains could be non-catalytic, but participates in alosteric regulation or as a c-di-GMP sensor [2]. DGCs and PDEs are integrated in multiple regulatory pathways and other domains able to sense c-di-GMP have been described (reviewed in [3]). One of these domains is the PilZ domain that is present in proteins implicated in different pathways such as cellulose production and pili formation [4]

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