Regulation of signaling directionality revealed by 3D snapshots of a kinase:regulator complex in action

• Published in: eLife 2016-12, Vol.5
• Main Authors: Trajtenberg, Felipe, Imelio, Juan A, Machado, Matías R, Larrieux, Nicole, Marti, Marcelo A, Obal, Gonzalo, Mechaly, Ariel E, Buschiazzo, Alejandro
• Format: Article
• Language: English
• Subjects: allosteric control of protein function; Bacillus subtilis; Bacillus subtilis - enzymology; Bacteriology; Biochemistry; Biochemistry, Molecular Biology; Biophysics and Structural Biology; cell signaling; Chemical Sciences; Cristallography; Crystallography, X-Ray; Dephosphorylation; Histidine; Histidine Kinase; Histidine Kinase - chemistry; Histidine Kinase - metabolism; Kinases; Life Sciences; Microbiology and Infectious Disease; Microbiology and Parasitology; Models, Molecular; Phosphatase; phosphoryl-transfer mechanism; Phosphorylation; Phosphotransferase; Protein Conformation; Protein Processing, Post-Translational; Proteins; Signal Transduction; structural biology; Transcription Factors; Transcription Factors - chemistry; Transcription Factors - metabolism; two component systems
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/elife.21422

Two-component systems (TCS) are protein machineries that enable cells to respond to input signals. Histidine kinases (HK) are the sensory component, transferring information toward downstream response regulators (RR). HKs transfer phosphoryl groups to their specific RRs, but also dephosphorylate them, overall ensuring proper signaling. The mechanisms by which HKs discriminate between such disparate directions, are yet unknown. We now disclose crystal structures of the HK:RR complex DesK:DesR from , comprising snapshots of the phosphotransfer and the dephosphorylation reactions. The HK dictates the reactional outcome through conformational rearrangements that include the reactive histidine. The phosphotransfer center is asymmetric, poised for dissociative nucleophilic substitution. The structural bases of HK phosphatase/phosphotransferase control are uncovered, and the unexpected discovery of a dissociative reactional center, sheds light on the evolution of TCS phosphotransfer reversibility. Our findings should be applicable to a broad range of signaling systems and instrumental in synthetic TCS rewiring.