Meeting Abstract

70.3  Friday, Jan. 6  The role of sensor regulator loci that mediate anaerobic respiration in host symbiotic competence of the Euprymna-Vibrio mutualism NOURABADI, Neda*; NISHIGUCHI, Michele K.; New Mexico State University; New Mexico State University nedan@nmsu.edu

The bioluminescent bacterium Vibrio fischeri and its sepiolid squid host Euprymna tasmanica has been a valuable model to underpin the mechanisms of recognition and specificity during the onset of symbiosis. Each partner recognizes and responds to one another in a molecular “cross-talk” within the host’s nascent light-emitting organ during the association. Vibrio bacteria can modulate their behavior through complex systematic interactions of different transcription factors, which can modulate gene transcription and therefore functions specific to the association. One example is the enzymes of the citric acid cycle during oxygen fluctuations. Coding genes are regulated mainly at the transcriptional level by the arcA/B two-component regulatory system, as well as cysB, which functions in the regulation of cysteine biosynthetic enzymes. Therefore, arcA/B and cysB are global regulators that control a number of genes involved in various metabolic pathways. We examined the physiological and metabolic consequences of mutation within these key regulatory loci among various strains of V. fischeri and measured their response under aerobic/anaerobic conditions. We hypothesized that arcA/B and cysB are responsible for utilization of carbon sources during anaerobic stress, and mutation of these genes will decouple the control of acidic by-products in the light organ. Thus, the major roles of arcA/B and cysB loci contribute to the physiological control under anaerobic stress during colonization of V. fischeri within the host squid light organ. Determining which molecular signals are responsible for establishing a successful association will help us better understand the subtle cues responsible for specificity in this environmentally transmitted mutualism.