Identification of two new genes involved in twitching motility in Pseudomonas aeruginosa

Shan, Zhiying; Xu, Haijin; Shi, Xingqi; Yu, Yan; Yao, Hongming; Zhang, Xiuming; Bai, Yanling; Gao, Caichang; Saris, Per E. J.; Qiao, Mingqiang

doi:10.1099/mic.0.27131-0

Cited by 20 publications

(16 citation statements)

References 31 publications

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“…Bacteria harboring disruptions in PA0171, PA1121 (YfiR), and PA3703 (WspF) were reported to have defective twitching motility (9,44). As this seemingly contradicts our observation that mutations in these loci promote pilus assembly and twitching motility, we investigated this further by examining these phenotypes in the PAO1 background.…”

Section: Figmentioning

confidence: 62%

Type IV Pilus Assembly in Pseudomonas aeruginosa over a Broad Range of Cyclic di-GMP Concentrations

et al. 2012

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Pseudomonas aeruginosa is a Gram-negative, opportunistic pathogen that utilizes polar type IV pili (T4P) for twitching motility and adhesion in the environment and during infection. Pilus assembly requires FimX, a GGDEF/EAL domain protein that binds and hydrolyzes cyclic di-GMP (c-di-GMP). Bacteria lacking FimX are deficient in twitching motility and microcolony formation. We carried out an extragenic suppressor screen in PA103⌬fimX bacteria to identify additional regulators of pilus assembly. Multiple suppressor mutations were mapped to PA0171, PA1121 (yfiR), and PA3703 (wspF), three genes previously associated with small-colony-variant phenotypes. Multiple independent techniques confirmed that suppressors assembled functional surface pili, though at both polar and nonpolar sites. Whole-cell c-di-GMP levels were elevated in suppressor strains, in agreement with previous studies that had shown that the disrupted genes encoded negative regulators of diguanylate cyclases. Overexpression of the regulated diguanylate cyclases was sufficient to suppress the ⌬fimX pilus assembly defect, as was overexpression of an unrelated diguanylate cyclase from Caulobacter crescentus. Furthermore, under natural conditions of high c-di-GMP, PA103⌬fimX formed robust biofilms that showed T4P staining and were structurally distinct from those formed by nonpiliated bacteria. These results are the first demonstration that P. aeruginosa assembles a surface organelle, type IV pili, over a broad range of cdi-GMP concentrations. Assembly of pili at low c-di-GMP concentrations requires a polarly localized c-di-GMP binding protein and phosphodiesterase, FimX; this requirement for FimX is bypassed at high c-di-GMP concentrations. Thus, P. aeruginosa can assemble the same surface organelle in distinct ways for motility or adhesion under very different environmental conditions.

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Section: Figmentioning

confidence: 62%

Type IV Pilus Assembly in Pseudomonas aeruginosa over a Broad Range of Cyclic di-GMP Concentrations

et al. 2012

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“…Mutants from a pool of Mini-Mu insertion mutants of PA68 (Shan et al, 2004) were screened for the changes of swimming motility. A mutant, I69, deficient in swimming motility was isolated.…”

Section: Identification and Sequence Analysis Of Putative Pfm Proteinmentioning

confidence: 99%

“…Using mini-Mu transposon technique (Shan et al, 2004), a gene with unknown function, annotated as PA2950 (named pfm in this paper) in P. aeruginosa genome sequence was identified to be required for the swimming motility. Meanwhile, the pfm mutant strain I69 was found to form intact flagellum under electron microscope (Li et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Identification and functional characterization of pfm, a novel gene involved in swimming motility of Pseudomonas aeruginosa

Bai

et al. 2007

Gene

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“…Twitching motility has been proven to be crucial for initial attachment of the pathogen to host epithelial tissue and for development of biofilm (35,41). Thus, we investigated the ability of our mutant strains to twitch, using an agar plate method.…”

Section: Fig 2 Isogenic Mutations Can Be Complemented By Expression Omentioning

confidence: 99%

“…Twitching motility allows dispersed, attached bacteria to migrate into microcolonies during biofilm maturation. In P. aeruginosa, twitching motility involves the action of type IV pili (35,41), which are also an attachment factor for this microorganism. It is possible that mutation of polB or PA14_46880 disrupts type IV pilus function, which in turn could decrease bacterial binding and biofilm maturation.…”

Section: Figmentioning

confidence: 99%

Involvement of Stress-Related Genes polB and PA14_46880 in Biofilm Formation of Pseudomonas aeruginosa

Alshalchi

Anderson

2014

Infect Immun

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eradicate. However, biofilm studies have been hampered by the fact that most assays utilize nonliving surfaces as biofilm attachment substrates. In an attempt to better understand the mechanisms behind P. aeruginosa biofilm formation, we performed a genetic screen to identify novel factors involved in biofilm formation on biotic and abiotic surfaces. We found that deletion of genes polB and PA14_46880 reduced biofilm formation significantly compared to that in the wild-type strain PA14 in an abiotic biofilm system. In a biotic biofilm model, wherein biofilms form on cultured airway cells, the ⌬polB and ⌬PA14_46880 strains showed increased cytotoxic killing of the airway cells independent of the total number of bacteria bound. Notably, deletion mutant strains were more resistant to ciprofloxacin treatment. This phenotype was linked to decreased expression of algR, an alginate transcriptional regulatory gene, under ciprofloxacin pressure. Moreover, we found that pyocyanin production was increased in planktonic cells of mutant strains. These results indicate that inactivation of polB and PA14_46880 may inhibit transition of P. aeruginosa from a more acute infection lifestyle to the biofilm phenotype. Future investigation of these genes may lead to a better understanding of P. aeruginosa biofilm formation and chronic biofilm infections. Chronic Pseudomonas aeruginosa infections in the lungs of cystic fibrosis (CF) patients are characterized by development of biofilm (1, 2). This biofilm formation protects these bacteria from stressful environmental factors, including antibiotic treatment and host defense mechanisms (1, 2). In particular, the biofilm extracellular matrix enhances the survival and persistence of P. aeruginosa by shielding the bacteria from the harsh conditions of CF patient lungs (3). Decreased growth rate, development of persisters, and expression of biofilm-specific resistance factors further enhance biofilm survival in the face of antibiotic and host stress (4,5). This adaptation to the CF lung environment is controlled by a complex regulatory network (6). Additionally, longterm exposure to stresses during chronic infection results in accumulation of mutations that contribute to persistent survival (7,8), suggesting that host pressures during infections actually enhance biofilm formation (9, 10). Thus, due to biofilm formation and subsequent phenotypic and genotypic adaptation to the harsh and stressful conditions, P. aeruginosa colonization often becomes lifelong in the CF lung (11), and it is a major factor contributing to CF complications, including respiratory failure and death (12).Genetic adaptation to the CF lung environment is thought to arise by a multistep process. Stress-induced DNA damage leads to mutation in DNA repair systems. Indeed, a high percentage of CF isolates have impaired DNA repair mechanisms (8,13,14). This initial defect then results in hypermutability and further genetic mutation (15, 16), which is particularly linked with acquired resistance to antibiotics and oxidative ...

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Identification of two new genes involved in twitching motility in Pseudomonas aeruginosa

Cited by 20 publications

References 31 publications

Type IV Pilus Assembly in Pseudomonas aeruginosa over a Broad Range of Cyclic di-GMP Concentrations

Type IV Pilus Assembly in Pseudomonas aeruginosa over a Broad Range of Cyclic di-GMP Concentrations

Identification and functional characterization of pfm, a novel gene involved in swimming motility of Pseudomonas aeruginosa

Involvement of Stress-Related Genes polB and PA14_46880 in Biofilm Formation of Pseudomonas aeruginosa

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