Dataset Information

Effect of extracytoplasmic function sigma factors on autoaggregation, hemagglutination, and cell surface properties of Porphyromonas gingivalis.

ABSTRACT: Porphyromonas gingivalis is a bacterium frequently isolated from chronic periodontal lesions and is involved in the development of chronic periodontitis. To colonize the gingival crevice, P. gingivalis has to adapt to environmental stresses. Microbial gene expression is regulated by transcription factors such as those in two-component systems and extracytoplasmic function (ECF) sigma factors. ECF sigma factors are involved in the regulation of environmental stress response genes; however, the roles of individual ECF sigma factors are largely unknown. The purpose of this study was to investigate the functions, including autoaggregation, hemagglutination, gingipain activity, susceptibility to antimicrobial agents, and surface structure formation, of P. gingivalis ECF sigma factors encoded by SigP (PGN_0274), SigCH (PGN_0319), PGN_0450, PGN_0970, and SigH (PGN_1740). Various physiological aspects of the sigP mutant were affected; autoaggregation was significantly decreased at 60 min (p < 0.001), hemagglutination activity was markedly reduced, and enzymatic activities of Kgp and Rgps were significantly decreased (p < 0.001). The other mutants also showed approximately 50% reduction in Rgps activity. Kgp activity was significantly reduced in the sigH mutant (p < 0.001). No significant differences in susceptibilities to tetracycline and ofloxacin were observed in the mutants compared to those of the wild-type strain. However, the sigP mutant displayed an increased susceptibility to ampicillin, whereas the PGN_0450 and sigH mutants showed reduced susceptibility. Transmission electron microscopy images revealed increased levels of outer membrane vesicles formed at the cell surfaces of the sigP mutant. These results indicate that SigP is important for bacterial surface-associated activities, including gingipain activity, autoaggregation, hemagglutination, vesicle formation, and antimicrobial susceptibility.

SUBMITTER: Fujise K

PROVIDER: S-EPMC5607195 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Effect of extracytoplasmic function sigma factors on autoaggregation, hemagglutination, and cell surface properties of Porphyromonas gingivalis.

Fujise Kazutaka K Kikuchi Yuichiro Y Kokubu Eitoyo E Okamoto-Shibayama Kazuko K Ishihara Kazuyuki K

PloS one 20170920 9

Porphyromonas gingivalis is a bacterium frequently isolated from chronic periodontal lesions and is involved in the development of chronic periodontitis. To colonize the gingival crevice, P. gingivalis has to adapt to environmental stresses. Microbial gene expression is regulated by transcription factors such as those in two-component systems and extracytoplasmic function (ECF) sigma factors. ECF sigma factors are involved in the regulation of environmental stress response genes; however, the ro ...[more]

PMID: 28931045

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Project description:Bacteria must sense alterations in their environment and respond with changes in function and/or structure in order to cope. Extracytoplasmic function sigma factors (ECF ?s) modulate transcription in response to cellular and environmental signals. The symbiotic nitrogen-fixing alphaproteobacterium Sinorhizobium meliloti carries genes for 11 ECF-like ?s (RpoE1 to -E10 and FecI). We hypothesized that some of these play a role in mediating the interaction between the bacterium and its plant symbiotic partner. The bacterium senses changes in its immediate environment as it establishes contact with the plant root, initiates invasion of the plant as the root nodule is formed, traverses several root cell layers, and enters plant cortical cells via endocytosis. We used genetics, transcriptomics, and functionality to characterize the entire S. meliloti cohort of ECF ?s. We discovered new targets for individual ?s, confirmed others by overexpressing individual ECF ?s, and identified or confirmed putative promoter motifs for nine of them. We constructed precise deletions of each ECF ? gene and its demonstrated or putative anti-? gene and also a strain in which all 11 ECF ? and anti-? genes were deleted. This all-ECF ? deletion strain showed no major defects in free-living growth, in Biolog Phenotype MicroArray assays, or in response to multiple stresses. None of the ECF ?s were required for symbiosis on the host plants Medicago sativa and Medicago truncatula: the strain deleted for all ECF ? and anti-? genes was symbiotically normal.IMPORTANCE Fixed (reduced) soil nitrogen plays a critical role in soil fertility and successful food growth. Much soil fertility relies on symbiotic nitrogen fixation: the bacterial partner infects the host plant roots and reduces atmospheric dinitrogen in exchange for host metabolic fuel, a process that involves complex interactions between the partners mediated by changes in gene expression in each partner. Here we test the roles of a family of 11 extracytoplasmic function (ECF) gene regulatory proteins (sigma factors [?s]) that interact with RNA polymerase to determine if they play a significant role in establishing a nitrogen-fixing symbiosis or in responding to various stresses, including cell envelope stress. We discovered that symbiotic nitrogen fixation occurs even when all 11 of these regulatory genes are deleted, that most ECF sigma factors control accessory functions, and that none of the ECF sigma factors are required to survive envelope stress.

Dataset Information

Effect of extracytoplasmic function sigma factors on autoaggregation, hemagglutination, and cell surface properties of Porphyromonas gingivalis.

Publications

Effect of extracytoplasmic function sigma factors on autoaggregation, hemagglutination, and cell surface properties of Porphyromonas gingivalis.

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