The Sigma Factor AlgU Plays a Key Role in Formation of Robust Biofilms by Nonmucoid Pseudomonas aeruginosa

被引:55
作者
Bazire, Alexis [1 ]
Shioya, Kouki [1 ]
Soum-Soutera, Emmanuelle [1 ]
Bouffartigues, Emeline [2 ]
Ryder, Cynthia [3 ]
Guentas-Dombrowsky, Linda [1 ]
Hemery, Gaelle [1 ,2 ]
Linossier, Isabelle [1 ]
Chevalier, Sylvie [2 ]
Wozniak, Daniel J. [3 ]
Lesouhaitier, Olivier [2 ]
Dufour, Alain [1 ]
机构
[1] Univ Bretagne Sud, LBCM, EA 3884, F-56321 Lorient, France
[2] Univ Rouen, Lab Microbiol Froid Signaux & Microenvironm, EA 4312, F-76821 Mont St Aignan, France
[3] Ohio State Univ, Ctr Microbial Interface Biol, Columbus, OH 43210 USA
关键词
GRAM-NEGATIVE BACTERIA; CYSTIC-FIBROSIS; GENE-EXPRESSION; FLAGELLUM BIOSYNTHESIS; REGULATED PROTEOLYSIS; MICROARRAY ANALYSIS; OUTER-MEMBRANE; PSL OPERON; IV PILI; QUORUM;
D O I
10.1128/JB.01633-09
中图分类号
Q93 [微生物学];
学科分类号
071005 ; 100705 ;
摘要
The extracytoplasmic function sigma factor AlgU of Pseudomonas aeruginosa is responsible for alginate overproduction, leading to mucoidy and chronic infections of cystic fibrosis patients. We investigated here the role of AlgU in the formation of nonmucoid biofilms. The algU mutant of P. aeruginosa PAO1 (PAOU) showed a dramatic impairment in biofilm formation under dynamic conditions. PAOU was defective both in cell attachment to glass and in development of robust, shear-resistant biofilms. This was explained by an impaired production of extracellular matrix, specifically of the exopolysaccharide Psl, as revealed by microscopy and enzyme-linked immunosorbent assay. Complementing the algU mutation with a plasmid-borne algU gene restored wild-type phenotypes. Compared with that in PAO1, expression of the psl operon was reduced in the PAOU strain, and the biofilm formation ability of this strain was partially restored by inducing the transcription of the psl operon. Furthermore, expression of the lectin-encoding lecA and lecB genes was reduced in the PAOU strain. In agreement with the requirement of LecB for type IV pilus biogenesis, PAOU displayed impaired twitching motility. Collectively, these genetic downregulation events explain the biofilm formation defect of the PAOU mutant. Promoter mapping indicated that AlgU is probably not directly responsible for transcription of the psl operon and the lec genes, but AlgU is involved in the expression of the ppyR gene, whose product was reported to positively control psl expression. Expressing the ppyR gene in PAOU partially restored the formation of robust biofilms.
引用
收藏
页码:3001 / 3010
页数:10
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