Carbohydrate and PepO control bimodality in competence development by Streptococcus mutans.
Mol Microbiol
; 112(5): 1388-1402, 2019 11.
Article
em En
| MEDLINE
| ID: mdl-31403729
ABSTRACT
In Streptococcus mutans, the alternative sigma factor ComX controls entry into genetic competence. Competence stimulating peptide (CSP) induces bimodal expression of comX, with only a fraction of the population becoming transformable. Curiously, the bimodality of comX is affected by peptides in the growth medium and by carbohydrate source. CSP elicits bimodal expression of comX in media rich in small peptides, but CSP elicits no response in defined media lacking small peptides. In addition, growth on certain sugars increases the proportion of the population that activates comX in response to CSP. By investigating the connection between media and comX bimodality, we find evidence for two mechanisms that modulate transcriptional positive feedback in the ComRS system, where comX bimodality originates. We find that the endopeptidase PepO suppresses the ComRS feedback loop, most likely by degrading the XIP/ComS feedback signal. Deletion of pepO eliminates comX bimodality, leading to a unimodal comX response to CSP in both defined and complex media. We also find that CSP stimulates the ComRS feedback system by upregulating comR in a carbohydrate source-dependent fashion. Our data provide mechanistic insight into how S. mutans regulates bimodality and explain the puzzle of growth medium effects on competence induction by CSP.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Streptococcus mutans
/
Proteínas de Bactérias
/
Fatores de Transcrição
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Competência de Transformação por DNA
Idioma:
En
Revista:
Mol Microbiol
Assunto da revista:
BIOLOGIA MOLECULAR
/
MICROBIOLOGIA
Ano de publicação:
2019
Tipo de documento:
Article
País de afiliação:
Estados Unidos