CCA addition by tRNA nucleotidyltransferase: Polymerization without translocation?

Pei Yong Shi, Nancy Maizels, Alan M. Weiner

Research output: Contribution to journalArticle

91 Scopus citations

Abstract

The CCA-adding enzyme repairs the 3'-terminal CCA sequence of all tRNAs. To determine how the enzyme recognizes tRNA, we probed critical contacts between tRNA substrates and the archaeal Sulfolobus shibatae class I and the eubacterial Escherichia coli class II CCA-adding enzymes. Both CTP addition to tRNA-C and ATP addition to tRNA-CC were dramatically inhibited by alkylation of the same tRNA phosphates in the acceptor stem and TΨC stem-loop. Both enzymes also protected the same tRNA phosphates in tRNA-C and tRNA-CC. Thus the tRNA substrate must remain fixed on the enzyme surface during CA addition. Indeed, tRNA-C cross-linked to the S. shibatae enzyme remains fully active for addition of CTP and ATP. We propose that the growing 3'-terminus of the tRNA progressively refolds to allow the solitary active site to reuse a single CTP binding site. The ATP binding site would then be created collaboratively by the refolded CC terminus and the enzyme, and nucleotide addition would cease when the nucleotide binding pocket is full. The template for CCA addition would be a dynamic ribonucleoprotein structure.

Original languageEnglish (US)
Pages (from-to)3197-3206
Number of pages10
JournalEMBO Journal
Volume17
Issue number11
DOIs
StatePublished - Jun 1 1998
Externally publishedYes

Keywords

  • ATP(CTP):tRNA nucleotidyltransferase
  • Cross-linking
  • Ribonucleoprotein

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

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