IIB   20738
INSTITUTO DE INVESTIGACIONES BIOLOGICAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Central signaling role for the conserved glycine hinge of bacterial chemoreceptors
Autor/es:
DIEGO A. MASSAZZA; ANDREA PEDETTA; CLAUDIA A. STUDDERT; KARINA HERRERA SEITZ
Reunión:
Congreso; LII Reunion Anual de SAIB; 2016
Resumen:
Chemotaxis requires the transmission of information from the environment to the flagellar motors. Chemoreceptors are dimeric transmembrane proteins with a periplasmic domain for ligand binding and a cytoplasmic domain consisting in a long hairpin that forms a four-helix coiled coil bundle. The activity of the CheA kinase, attached to the tip of the cytoplasmic domain, is modulated in response to external signals. The mode of signal propagation along the long chemoreceptor rod is still under study. In this work we focus on the role of three conserved glycine residues, two in the N-terminal (G340-G341) and one in the C-terminal (G439) helix of the hairpin, that conform a hinge in the serine receptor Tsr. We carried out random-codon mutagenesis and selected the non-functional variants. We obtained 14 different replacements, 13 of which retained native receptor interactions and subcellular localization, but were defective in kinase control, as assessed by flagellar rotation assays. All the mutants in G439 were unable to activate the kinase and showed an hyper-methylated pattern, indicative of a locked-OFF receptor conformation. Second-site revertants showed alterations on the methylation region or near the mutated glycine and recover the ability of activate the kinase. These results indicate that the glycine hinge is implicated in the receptor ON-OFF transition during signaling.