Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2007 Aug;153(Pt 8):2765-2773.
doi: 10.1099/mic.0.2007/007468-0.

Genetic characterization of the hdrRM operon: a novel high-cell-density-responsive regulator in Streptococcus mutans

Justin Merritt  1 , Lanyan Zheng  2 , Wenyuan Shi  3   1 , Fengxia Qi  1
Affiliations
Free article

Genetic characterization of the hdrRM operon: a novel high-cell-density-responsive regulator in Streptococcus mutans

Justin Merritt et al. Microbiology (Reading). 2007 Aug.
Free article

Abstract

Many species of bacteria can adhere to surfaces and grow as sessile communities. The continued accumulation of bacteria can eventually lead to the extremely high-cell-density environment characteristic of many biofilms or cell colonies. This is the normal habitat of the cariogenic species Streptococcus mutans, which normally resides in the high-cell-density, multispecies community commonly referred to as dental plaque. Previous work has demonstrated that the transcription of two separate bacteriocins can be activated by the high-cell-density conditions created through the centrifugation and incubation of cell pellets. In this study, we identified an uncharacterized two-gene operon that was induced >10-fold by conditions of high cell density. The genes of the operon encode a putative transcription regulator and a membrane protein, which were renamed as hdrR and hdrM, respectively. A transcription fusion to the hdrRM operon confirmed its induction by high cell density. Mutation of hdrM abolished bacteriocin production, greatly increased natural competence, reduced the growth rate, and severely affected biofilm formation. Interestingly, no obvious phenotypes were observed from a non-polar mutation of hdrR or mutations affecting the entire operon. These data suggest that the hdrRM operon may constitute a novel regulatory system responsible for mediating a cellular response to a high-cell-density environment.

PubMed Disclaimer

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

Publication types

MeSH terms

LinkOut - more resources