The role of 23S ribosomal RNA residue A2451 in peptide bond synthesis revealed by atomic mutagenesis.
Peptide bond formation is a fundamental reaction in biology, catalyzed by the ribosomal peptidyl-transferase ribozyme. Although all active-site 23S ribosomal RNA nucleotides are universally conserved, atomic mutagenesis suggests that these nucleobases do not carry functional groups directly involved in peptide bond formation. Instead, a single ribose 2'-hydroxyl group at A2451 was identified to be of pivotal importance. Here, we altered the chemical characteristics by replacing its 2'-hydroxyl with selected functional groups and demonstrate that hydrogen donor capability is essential for transpeptidation. We propose that the A2451-2'-hydroxyl directly hydrogen bonds to the P-site tRNA-A76 ribose. This promotes an effective A76 ribose C2'-endo conformation to support amide synthesis via a proton shuttle mechanism. Simultaneously, the direct interaction of A2451 with A76 renders the intramolecular transesterification of the peptide from the 3'- to 2'-oxygen unfeasible, thus promoting effective peptide bond synthesis.
Lang
Kathrin
K
Institute of Organic Chemistry, Center for Molecular Biosciences (CMBI), University of Innsbruck, Innsbruck, Austria.
Erlacher
Matthias
M
Wilson
Daniel N
DN
Micura
Ronald
R
Polacek
Norbert
N
D001483:Base Sequence; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009690:Nucleic Acid Conformation; D010455:Peptides / Q000138:chemical synthesis*; D012338:RNA, Ribosomal, 23S / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D010455:Peptides; D012338:RNA, Ribosomal, 23S