1、Quorum-sensing,1970s Vibrio fischeri e V. harveyi Symbionts, inhabitants of the light organs of fish and squids. Bacterial densities: 1010 1011 CFU/mL.,Light is emitted by bacteria living in the light organs of fish,Light is produced after transcription activation of the lux operon,Synthesis of HSL
2、a signaling molecule,Signaling molecules are diverse,Swarming of different Pseudomonas aeruginosa strains after 48 h on FAB-glucose medium with 0.45% noble agar.,Morris J D et al. Appl. Environ. Microbiol. 2011;77:8310-8317,The Tojan horse,Qurum sensing regulation,Pseudomonas aeruginosa LasI/LasR, r
3、hlI/rhlR and PQS quorum-sensing systems,Rutherford S T , and Bassler B L Cold Spring Harb Perspect Med 2012;2:a012427,S. aureus Agr QS circuit. The autoinducing peptide (AIP) is synthesized as a precursor from agrD. The AIP transporter AgrB processes the precursor to the mature AIP and transports it
4、 out of the cell. AIPs are detected by a two-component signal transduction pathway. AgrC is the membrane-bound histidine kinase and AgrA is the response regulator. Phosphorylated AgrA activates the P2 and P3 promoters encoding the agr operon (called RNAII) and the RNAIII regulatory RNA, respectively
5、. RNAIII posttranscriptionally activates virulence factor production and represses expression of rot, the repressor of toxins, leading to further derepression of virulence factors.,Bacterial Biofilms,Structured communities of bacteria living together,Formation of biofilms,https:/ aeruginosa AIs and inhibitors.,Rutherford S T , and Bassler B L Cold Spring Harb Perspect Med 2012;2:a012427,Lactonases enzymes that destroy the lactonde ring of AHLs,
