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The malate sensing two-component system MaeKR is a non-canonical class of sensory complex for C4-dicarboxylates

DOI: 10.1038/s41598-017-02900-z DOI Help

Authors: L. Miguel-romero (Instituto de Biomedicina de Valencia (IBV-CSIC)) , Patricia Casino (Universitat de València) , J. M. Landete (Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC); Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)) , V. Monedero (Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC)) , M. Zuniga (Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC)) , A. Marina (Instituto de Biomedicina de Valencia (IBV-CSIC))
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Scientific Reports , VOL 7

State: Published (Approved)
Published: June 2017
Diamond Proposal Number(s): 14739

Open Access Open Access

Abstract: Microbial colonization of different environments is enabled to a great extent by the plasticity of their sensory mechanisms, among them, the two-component signal transduction systems (TCS). Here, an example of TCS plasticity is presented: the regulation of L-malate catabolism via malic enzyme by MaeRK in Lactobacillales. MaeKR belongs to the citrate family of TCS as the Escherichia coli DcuSR system. We show that the Lactobacillus casei histidine-kinase MaeK is defective in autophosphorylation activity as it lacks a functional catalytic and ATP binding domain. The cognate response regulator MaeR was poorly phosphorylated at its phosphoacceptor Asp in vitro. This phosphorylation, however, enhanced MaeR binding in vitro to its target sites and it was required for induction of regulated genes in vivo. Elucidation of the MaeR structure revealed that response regulator dimerization is accomplished by the swapping of α4-β5-α5 elements between two monomers, generating a phosphoacceptor competent conformation. Sequence and phylogenetic analyses showed that the MaeKR peculiarities are not exclusive to L. casei as they are shared by the rest of orthologous systems of Lactobacillales. Our results reveal MaeKR as a non-canonical TCS displaying distinctive features: a swapped response regulator and a sensor histidine kinase lacking ATP-dependent kinase activity.

Journal Keywords: Cellular microbiology; X-ray crystallography

Subject Areas: Biology and Bio-materials

Instruments: I04-Macromolecular Crystallography