Skip to main page content
U.S. flag

An official website of the United States government

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 1988 Feb 15;263(5):2255-63.

Purification, structure, and properties of Escherichia coli tRNA pseudouridine synthase I

Affiliations
  • PMID: 3276686
Free article

Purification, structure, and properties of Escherichia coli tRNA pseudouridine synthase I

H O Kammen et al. J Biol Chem. .
Free article

Abstract

The RNA modification enzyme, tRNA pseudouridine synthase I has been isolated in 95% purity from an Escherichia coli strain harboring a multicopy plasmid with a 2.3-kilobase pair insert from the hisT operon. Its molecular size, amino acid composition, and amino-terminal sequence correspond to those predicted by the structure and expression of the hisT gene. Enzyme activity, as measured by a 3H release assay, is unaffected by pretreatment of tRNA pseudouridine synthase I with micrococcal nuclease and is optimized by the addition of a monovalent cation and thiol reductant. The activity is inhibited by all tRNA species tested, including substrates, modified tRNAs, nonsubstrates, or tRNAs containing 5-fluorouridine. Binding of tRNA pseudouridine synthase I occurs with both substrate and nonsubstrate tRNAs and does not require a monovalent cation. Our findings are consistent with a multistep mechanism whereby tRNA pseudouridine synthase I first binds nonspecifically and then forms transient covalent adducts with tRNA substrates. In the absence of other proteins, purified tRNA pseudouridine synthase I forms psi at all three modification sites known to be affected in hisT mutants. The 36.4-kDa polypeptide product of the gene adjacent to hisT, whose translation is linked to that of tRNA pseudouridine synthase I, is not a functional subunit for tRNA pseudouridine synthase I activity, nor is it a separate synthase acting at one of the three loci.

PubMed Disclaimer

Similar articles

Cited by

Publication types

LinkOut - more resources