Molecular cloning of a ribonuclease H (RNase HI) gene from an extreme thermophile Thermus thermophilus HB8: A thermostable rnase H can functionally replace the Escherichia coli enzyme in vivo

Mitsuhiro Itaya, Kanae Kondo

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

A DNA fragment encoding Ribonuclease H (EC 3. 1. 26. 4) was isolated from an extreme thermophilic bacterium, Thermus thermophilus HB8, by its ability to complement the temperature-sensitive growth of an Escherichia coli rnhA deficient mutant. The primary amino acid sequence showed 56% similarity to that of E. coli RNase HI but little or no homology to E. coli RNase HII. Enzymes derived from thermophilic organisms tend to have fewer cysteines than their bacterial counterparts. However, T. thermophilus RNase H has one more cysteine than its E. coli homologue. Stability of the RNase H in extracts of T. thermophilus to elevated temperatures was the same for the protein expressed in E. coli. T. thermophilus RNase H should, therefore, be a useful tool for editing RNA-DNA hybrid molecules at higher temperatures and may also be stable enough to be used in a cyclical process. It was suggested that regulation of expression of the RNase H may be diflerent from that of E. coli. RNase HI.

Original languageEnglish
Pages (from-to)4443-4449
Number of pages7
JournalNucleic acids research
Volume19
Issue number16
DOIs
Publication statusPublished - 1991 Aug 25

ASJC Scopus subject areas

  • Genetics

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