6q2d
From Proteopedia
Crystal structure of Methanobrevibacter smithii Dph2 in complex with Methanobrevibacter smithii elongation factor 2
Structural highlights
Function[A5UMY5_METS3] Catalyzes the first step of diphthamide biosynthesis, i.e. the transfer of the 3-amino-3-carboxypropyl group from S-adenosyl-L-methionine (SAM) to the C2 position of the imidazole ring of the target histidine residue in translation elongation factor 2 (EF-2).[PIRNR:PIRNR004967] [A0A2H4U7K7_METSM] Catalyzes the GTP-dependent ribosomal translocation step during translation elongation. During this step, the ribosome changes from the pre-translocational (PRE) to the post-translocational (POST) state as the newly formed A-site-bound peptidyl-tRNA and P-site-bound deacylated tRNA move to the P and E sites, respectively. Catalyzes the coordinated movement of the two tRNA molecules, the mRNA and conformational changes in the ribosome.[HAMAP-Rule:MF_00054][SAAS:SAAS00384500] Publication Abstract from PubMedElongation factor 2 (EF-2), a five-domain, GTP-dependent ribosomal translocase of archaebacteria and eukaryotes, undergoes post-translational modification to form diphthamide on a specific histidine residue in domain IV prior to binding the ribosome. The first step of diphthamide biosynthesis in archaebacteria is catalyzed by Dph2, a homodimeric radical S-adenosylmethionine (SAM) enzyme having a noncanonical architecture. Here, we describe a 3.5 A resolution crystal structure of the Methanobrevibacter smithii (Ms) Dph2 homodimer bound to two molecules of MsEF-2, one of which is ordered and the other largely disordered. MsEF-2 is bound to both protomers of MsDph2, with domain IV bound to the active site of one protomer and domain III bound to a surface alpha-helix of an adjacent protomer. The histidine substrate of domain IV is inserted into the active site, which reveals for the first time the architecture of the Dph2 active site in complex with its target substrate. We also determined a high-resolution crystal structure of isolated MsDph2 bound to 5'-methylthioadenosine that shows a conserved arginine residue preoriented by conserved phenylalanine and aspartate residues for binding the carboxylate group of SAM. Mutagenesis experiments suggest that the arginine plays an important role in the first step of diphthamide biosynthesis. The Crystal Structure of Dph2 in Complex with Elongation Factor 2 Reveals the Structural Basis for the First Step of Diphthamide Biosynthesis.,Fenwick MK, Dong M, Lin H, Ealick SE Biochemistry. 2019 Oct 14. doi: 10.1021/acs.biochem.9b00718. PMID:31566354[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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