title: The C-A mismatch base pair and the single-strand terminus in the E. coli initiator tRNA(fMet) acceptor stem adopt unusual conformations.
abstract: Acceptor stem variants of tRNA(fMet) (Escherichia coli) have been characterized by nuclear magnetic resonance. The wild type contains a C1-A72 mismatch pair which is crucial for its biological function. For comparison, the mismatch was replaced by regular pairs U1-A72 and C1-G72. Further variants contain an altered discriminator base, G73, or a G1-C72/U73 combination. The stems of variants U1-A72/A73 and C1-G72/A73 have A-RNA geometry, which extends essentially to the single-strand terminus. C1-A72/G73 variant and wild type are structurally almost identical. C1 and A72 adopt peculiar conformations with C1 being largely destacked with respect to G2, while A73 stacks upon C1. The unique arrangement of the mismatch causes a distinctly different orientation of the single-strand terminus compared to variants with regular 1-72 base pairs, and to formyltransferase-complexed tRNA(fMet).
authors.affiliation: Laboratorium für Biochemie, Universität Bayreuth, Universitätsstrasse 30, D-95440, Bayreuth, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Zuleeg
authors.forename: M
authors.initials: M
authors.lastname: Vogtherr
authors.forename: H
authors.initials: H
authors.lastname: Schübel
authors.forename: S
authors.initials: S
authors.lastname: Limmer
mesh_terms: D000225:Adenine; D020137:Base Pair Mismatch; D001665:Binding Sites; D003596:Cytosine; D004926:Escherichia coli / Q000235:genetics*; D014644:Genetic Variation; D019877:Hydroxymethyl and Formyl Transferases / Q000378:metabolism*; D019906:Nuclear Magnetic Resonance, Biomolecular; D009690:Nucleic Acid Conformation; D012329:RNA, Bacterial / Q000737:chemistry* / Q000378:metabolism; D012358:RNA, Transfer, Met / Q000737:chemistry* / Q000378:metabolism
chemical_list: D012329:RNA, Bacterial; D012358:RNA, Transfer, Met; C089238:fMet-tRNA(fMet); D003596:Cytosine; D019877:Hydroxymethyl and Formyl Transferases; C021561:methionyl-tRNA formyltransferase; D000225:Adenine