孙宝林实验室 研究方向

Bacterial small-molecule signaling, quorum sensing, biofilm formation and virulence

Our main research is directed towards understanding the molecular mechanisms and signaling network involved in bacterial cell-cell communication, biofilm formation and pathogenesis. Quorum sensing is a bacterial cell-cell communication process, which involves the production, secretion and detection of extracellular small-molecule signals called autoinducers. Accumulation of a threshold autoinducer concentration, which corresponds to increasing cell density, initiates a signal transduction cascade that ultimately results in a coordinated and population-wide alteration in bacterial behaviors such as bioluminescence, polysaccharide secretion, biofilm formation and virulence. Bacterial biofilms are surface-attached communities and present significant problems in industry and medicine. Recent studies have indicated that 3',5'-cyclic diguanylic acid plays a vital role in regulating complex cellular processes that are also controlled by quorum sensing. This novel second messenger 3',5'-cyclic diguanylic acid is synthesized by a class of enzymes containing GGDEF domains and hydrolyzed by EAL or HD-GYP domain-containing proteins. How extracellular quorum sensing signals are converted into intracellular second messengers that coordinate gene expression and physiological activities, however, remains elusive. We use gram-negative bacteria Escherichia coli and Salmonella typhimurium, and gram-positive bacteria Staphylococcus aureus, Staphylococcus epidermidis and Mycobacterium tuberculosis as model organisms for our research. Our long-term goal is to elucidate the small molecule-mediated signaling network and the regulatory mechanisms involved in quorum sensing, biofilm formation and virulence, and to provide potential drug targets for treatment of biofilm-associated diseases.