Validation of crucial structural elements for the signal transduction mechanism of the thermosensor histidine kinase DesK

ALBANESI, DANIELA; TSAI, YI TING; TRAJTENBERG, FELIPE; ALZARI, PEDRO; BUSCHIAZZO, ALEJANDRO; DE MENDOZA, DIEGO

Montecatini Terme

Conferencia; 16th International Conference on Bacilli. 6th Conference on Functional Genomics of Gram-positive Microorganisms; 2011

The Scripps Reasearch Institute

DesK is a membrane-bound histidine kinase from Bacillus subtilis suited to remodel membrane fluidity when the temperature drops below~30°C. We have recently reported six crystal structures of the entire cytoplasmic catalytic core of DesK trapped in three conformational states corresponding to alternate functions of the protein along its catalytic cycle, allowing us to propose a model to account for the regulation mechanism of the catalytic activities of this protein1. Comparison of the different structures invited the hypothesis that contacts between the central dimerization histidine phosphotransfer domain (DHp) and the ATP-binding domains (ABDs), as well as a dynamic N-terminal coiled-coil, support a labile association to be released for autophosphorylation and maintained for the phosphatase activity, under control of the sensor domain upon signal perception. To test this hypothesis we have performed structure-based mutagenesis. In vivo studies with a set of DesK variants stress the relevance of these structural elements to control its output activity and confirm the importance of the rotational and shifting movements in the conserved DHp domain on the signal transduction mechanism of this sensor protein.1. Albanesi D., Martín M., Trajtenberg F., Mansilla M.C., Haouz A., Alzari P.M., de Mendoza D. and Buschiazzo A. Proc. Natl. Acad. Sci. USA. 106,16185-16190 (2009).