Synthesis of ppGpp impacts type IX secretion and biofilm matrix formation in Porphyromonas gingivalis

• Published in: NPJ biofilms and microbiomes Vol. 6; no. 1; p. 5
• Main Authors: Kim, Hey-Min, Davey, Mary E.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 31-01-2020; Nature Publishing Group
• Subjects: 631/326/1320; 631/326/46; Animals; Bacteria; Bacterial Proteins - metabolism; Bacteroidaceae Infections - microbiology; Bacteroidaceae Infections - mortality; Biofilms; Biofilms - growth & development; Biomedical and Life Sciences; Disease Models, Animal; External stimuli; Gene Expression Regulation, Bacterial; Growth rate; Guanosine Pentaphosphate - biosynthesis; Lepidoptera - microbiology; Life Sciences; Medical Microbiology; Membrane vesicles; Microbial Ecology; Microbial Genetics and Genomics; Microbiology; Oral cavity; Porphyromonas gingivalis; Porphyromonas gingivalis - metabolism; Porphyromonas gingivalis - physiology; Secretion; Signal Transduction; Stress response; Stress, Physiological; Stringent response; Survival Analysis; Virulence
• ISSN: 2055-5008; 2055-5008
• DOI: 10.1038/s41522-020-0115-4

In order to persist, bacteria need to adjust their physiological state in response to external and internal cues. External stimuli are often referred to as stressors. The stringent response, mediated by the alarmone (p)ppGpp, is central to the stress response in many bacteria; yet, there is limited knowledge regarding the role of (p)ppGpp signaling in bacteria belonging to the phylum Bacteroidetes. Like its counterparts in the gut (e.g.,
Bacteroides thetaiotaomicron
and
Bacteroides fragilis
),
Porphyromonas gingivalis
persists in close association with its human host. Given the potential for numerous perturbations in the oral cavity, and the fact that
P. gingivalis
can enter and replicate within host cells, we hypothesized that (p)ppGpp is a key signaling molecule for stress adaptation and persistence. Here, we show that accumulation of ppGpp in
P. gingivalis
is governed by two homologous enzymes, designated Rel, and RshB, and that ppGpp signaling affects growth rate, survival, biofilm formation, production of outer membrane vesicles, and expression of genes encoding type IX secretion structural and cargo proteins. Overall, our findings provide a potential mechanism by which biofilm formation and virulence of
P. gingivalis
are integrated via ppGpp signaling, a regulatory mechanism central to bacterial survival in dynamic environments.