Structural highlights
Publication Abstract from PubMedMembrane bound histidine kinases (HKs) are ubiquitous sensors of extracellular stimuli in bacteria. However, a uniform structural model is still missing for their transmembrane signaling mechanism. Here, we used solid-state NMR in conjunction with crystallography, solution NMR and distance measurements to investigate the transmembrane signaling mechanism of a paradigmatic citrate sensing membrane embedded HK, CitA. Citrate binding in the sensory extracytoplasmic PAS domain (PASp) causes the linker to transmembrane helix 2 (TM2) to adopt a helical conformation. This triggers a piston-like pulling of TM2 and a quaternary structure rearrangement in the cytosolic PAS domain (PASc). Crystal structures of PASc reveal both anti-parallel and parallel dimer conformations. An anti-parallel to parallel transition upon citrate binding agrees with interdimer distances measured in the lipid embedded protein using a site-specific (19)F label in PASc. These data show how Angstrom scale structural changes in the sensor domain are transmitted across the membrane to be converted and amplified into a nm scale shift in the linker to the phosphorylation subdomain of the kinase. Mechanism of sensor kinase CitA transmembrane signaling.,Zhang XC, Xue K, Salvi M, Schomburg B, Mehrens J, Giller K, Stopp M, Weisenburger S, Boning D, Sandoghdar V, Unden G, Becker S, Andreas LB, Griesinger C Nat Commun. 2025 Jan 22;16(1):935. doi: 10.1038/s41467-024-55671-3. PMID:39843904[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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