Participation of acetylpseudouridine in the synthesis of a peptide bond in vitro.
Uracil, uridine, and pseudouridine were acetylated by refluxing in acetic anhydride, and the products of acetylation were incubated with a synthetic peptide (1-21) that corresponds to the N-terminal 21 amino acid residues of human myelin basic protein. Peptide bond formation, at the N alpha terminus in peptide 1-21, was obtained with acetyluracil and acetylpseudouridine, but not with acetyluridine. Transfer of an acetyl group from acetyluracil and acetylpseudouridine depended on acetylation in the N-heterocycle. X-ray crystallographic analysis definitively established N-1 as the site of acetylation in acetyluracil. Mass spectrometry of the acetylation products showed that one acetyl group was transferred to peptide 1-21, in water, by either acetyluracil or acetylpseudouridine at pH approximately 6. Release of the acetyl group by acylaminopeptidase regenerated peptide 1-21 (mass spectrometry) and automated sequencing (for five cycles) of the regenerated (deacetylated) peptide demonstrated that the N terminus was intact. The findings are discussed in the context of a possible role for pseudouridine in ribosome-catalyzed peptidyltransfer, with particular reference being made to similarities between the possible mechanism of acyl transfer by acetyluracil/pseudouridine and the mechanism of carboxyl transfer by carboxylbiotin in acetyl CoA carboxylase. The possibility that idiosyncratic appearance of a wide range of acyl substituents in myelin basic protein could be related to a peculiar involvement of ribosomal pseudouridine is mentioned.
Wood
D D
DD
Department of Biochemistry, Hospital for Sick Children, Toronto, Ontario, Canada.
Pang
H
H
Hempel
A
A
Camerman
N
N
Lane
B G
BG
Moscarello
M A
MA
D000107:Acetylation; D018360:Crystallography, X-Ray; D006801:Humans; D013058:Mass Spectrometry; D004676:Myelin Basic Protein / Q000737:chemistry*; D010455:Peptides / Q000138:chemical synthesis*; D011560:Pseudouridine / Q000031:analogs & derivatives* / Q000737:chemistry
D004676:Myelin Basic Protein; D010455:Peptides; C095672:acetylpseudouridine; D011560:Pseudouridine