MICRB316 Lecture Notes - Lecture 12: Luxo, Pyocyanin, Hfq Protein
8 Mar 2014
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Document Summary
Ai-1 or aip are produced and detected in a species specific way. It was previously thought that 2 autoinducers would play different roles in a cell: harveyi (not at all like v. fischeri); has bioluminescence, but it is marine planktonic, not in squid. Luxp is homologous to an e. coli ribose binding protein; binds ai-2 in the periplasm. Luxp+ai-2 bind luxq which is a hybrid 2c sk with a periplasmic sensory domain, and cytoplasmic hk & rr. Luxn is also a hybrid 2c sk-rr; binds ai-1. (hai-1) Signal is transduced through phosphorelay to luxu and then luxo (rr) Activated (phospho) luxo acts (with sigma 54) as a tn activator of genes for small rnas. At low cell densities, luxn & luxq act as kinases and transfer phosphoryl group to shared hpt protein luxu. Luxu transmits this to rr protein luxo activates expression of the repressor rna + protein, which negatively regulates luxcdabe (luciferase) > no light.
