Title:Quorum Sensing and Biofilms in the Pathogen, Streptococcus pneumoniae
VOLUME: 21 ISSUE: 1
Author(s):Joana Galante, Alfred C-Y Ho, Sarah Tingey and Bambos M. Charalambous
Affiliation:Centre for Clinical Microbiology, UCL Medical School Royal Free Campus Rowland Hill Street London NW3 2PF.
Keywords:Streptococcus pneumoniae, biofilm, quorum sensing, mucosal colonizers, nasopharynx, infectious disease.
Abstract:Bacteria are able to colonize and thrive in a variety of different environments as a biofilm, but only within the last half century
new insights have been gained in this complex biosystem. Bacterial biofilms play a major role in human health by forming a defensive
barrier against antibacterial chemical therapeutics and other potential pathogens, and in infectious disease when the bacteria invade normally
sterile compartments. Quorum sensing is the signaling network for cell-to-cell communication and utilized by bacteria to regulate biofilms
and other cellular processes. This review will describe recent advances in quorum sensing and biofilms. Initially, it will focus on Streptococcus
pneumoniae biofilm regulation and the involvement of the ComABCDE pathway. As part of this review an original analysis of the
genotypic and phenotypic variation of the signaling molecule, ComC and its cognate receptor ComD, firstly within the pneumococcal
species and then within the genus Streptococcus will be presented. Additionally, a pathway similar to ComABCDE, the BlpABCSRH that
regulates bacteriocin and immunity protein production that inhibit the growth of competing bacteria will be described. This review will
then examine a third quorum sensing mechanism in the pneumococcus, the LuxS/AI-2, and present a novel gene and protein sequence
comparative analysis that indicates its occurrence is more universal across bacterial genera compared with the Com pathway, with more sequence
similarities between bacterial genera that are known to colonize the mucosal epithelium.
