Genes involved in the repression of mutacin I production in Streptococcus mutans.
Streptococcus mutans is considered a primary pathogen for human dental caries. Its ability to produce a variety of peptide antibiotics called mutacins may play an important role in its invasion and establishment in the dental biofilm. S. mutans strain UA140 produces two types of mutacins, the lantibiotic mutacin I and the non-lantibiotic mutacin IV. In a previous study, we constructed a random insertional-mutation library to screen for genes involved in regulating mutacin I production, and found 25 genes/operons that have a positive effect on mutacin I production. In this study, we continued our previous work to identify genes that are negatively involved in mutacin I production. By using a high-phosphate brain heart infusion agar medium that inhibited mutacin I production of the wild-type, we isolated 77 clones that consistently produced mutacin I under repressive conditions. From the 34 clones for which we were able to obtain a sequence, 17 unique genes were identified. These genes encompass a variety of functional groups, including central metabolism, surface binding and sugar transport, and unknown functions. Some of the 17 mutations were further characterized and shown to increase mutacin gene expression during growth when the gene is usually not expressed in the wild-type. These results further demonstrate an intimate and intricate connection between mutacin production and the overall cellular homeostasis.
Nguyen
Trang
T
UCLA School of Dentistry, Los Angeles, CA 90095, USA.
Zhang
Zhijun
Z
College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73034, USA.
Huang
I-Hsiu
IH
College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73034, USA.
Wu
Chenggang
C
College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73034, USA.
Merritt
Justin
J
College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73034, USA.
Shi
Wenyuan
W
UCLA School of Dentistry, Los Angeles, CA 90095, USA.
Qi
Fengxia
F
College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73034, USA.
D000900:Anti-Bacterial Agents / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001430:Bacteriocins / Q000378:metabolism*; D015536:Down-Regulation; D015964:Gene Expression Regulation, Bacterial; D009154:Mutation; D013295:Streptococcus mutans / Q000235:genetics* / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001430:Bacteriocins; C416548:mutacin I