Structural highlights
FunctionPublication Abstract from PubMedProtein phosphorylation, a key post-translational modification, is mediated by various protein kinases. The bacterial PrkA/YeaG is recognized as an atypical protein kinase, but its activity remains elusive. This study investigated the structural and functional characteristics of a PrkA/YeaG homologue, TpkB, from Thermus thermophilus HB8. Using cryo-electron microscopy, the structures of TpkB in apo and AMPPNP-bound forms were determined, revealing a hexameric ring architecture characteristic of AAA + superfamily proteins. The TpkB protomer is comprised of an N-terminal domain, an ATPase domain, and a LID domain. The ATPase domain contains conserved sequence motifs associated with ATPase activity, whereas the other domains present a novel fold. TpkB exhibits structural similarity to MoxR family proteins, which possess chaperone-like functions in conjunction with von Willebrand factor A (vWA) domain proteins. Structural and gene neighborhood analyses suggested a functional link between PrkA/YeaG proteins and vWA domain proteins. Biochemical analyses demonstrated that TpkB exhibited ATPase activity and chaperone-like activity, but lacked detectable protein kinase activity. These findings establish TpkB as a novel member of the AAA+ superfamily with potential chaperone functions, providing new insights into the PrkA/YeaG family. Structure and biochemical analyses suggest that PrkA/YeaG protein of Thermus thermophilus functions as a putative molecular chaperone.,Torii M, Kanno R, Mizoguchi A, Humbel BM, Tani K, Masui R J Biochem. 2026 Jun 15:mvag041. doi: 10.1093/jb/mvag041. PMID:42294598[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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