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Publication Abstract from PubMed

Motility is a central feature of many microorganisms and provides an efficient strategy to respond to environmental changes. Bacteria and archaea have developed fundamentally different rotary motors enabling their motility, termed flagellum and archaellum, respectively. Bacterial motility along chemical gradients, called chemotaxis, critically relies on the response regulator CheY, which, when phosphorylated, inverses the rotational direction of the flagellum via a switch complex at the base of the motor. The structural difference between archaellum and flagellum and the presence of functional CheY in archaea raises the question of how the CheY protein changed to allow communication with the archaeal motility machinery. Here we show that archaeal CheY shares the overall structure and mechanism of magnesium-dependent phosphorylation with its bacterial counterpart. However, bacterial and archaeal CheY differ in the electrostatic potential of the helix alpha4. The helix alpha4 is important in bacteria for interaction with the flagellar switch complex, a structure that is absent in archaea. We demonstrated that phosphorylation-dependent activation, and conserved residues in the archaeal CheY helix alpha4, are important for interaction with the archaeal-specific adaptor protein CheF. This forms a bridge between the chemotaxis system and the archaeal motility machinery. Conclusively, archaeal CheY proteins conserved the central mechanistic features between bacteria and archaea, but differ in the helix alpha4 to allow binding to an archaellum-specific interaction partner.

Structure and function of the archaeal response regulator CheY.,Quax TEF, Altegoer F, Rossi F, Li Z, Rodriguez-Franco M, Kraus F, Bange G, Albers SV Proc Natl Acad Sci U S A. 2018 Jan 22. pii: 1716661115. doi:, 10.1073/pnas.1716661115. PMID:29358409^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.