Catalytic center of an archaeal type 2 ribonuclease H as revealed by X-raycrystallographic and mutational analyses

Muroya, A Tsuchiya, D Ishikawa, M Haruki, M Morikawa, M Kanaya, S Morikawa, K

A. Muroya et al., Catalytic center of an archaeal type 2 ribonuclease H as revealed by X-raycrystallographic and mutational analyses, PROTEIN SCI, 10(4), 2001, pp. 707-714

34

INGLESE

Article

Biochemistry & Biophysics

PROTEIN SCIENCE

0961-8368 → ACNP

10

4

2001

707 - 714

ISI

0961-8368(200104)10:4<707:CCOAAT>2.0.ZU;2-Z

The catalytic center of an archaeal Type 2 RNase H has been identified by a combination of X-ray crystallographic and mutational analyses. The crystal structure of the Type 2 RNase H from Thermococcus kodakaraensis KOD1 has r evealed that the N-terminal major domain adopts the RNase H fold, despite t he poor sequence similarity to the Type 1 RNase H. Mutational analyses show ed that the catalytic reaction requires four acidic residues, which are wel l conserved in the Type 1 RNase H and the members of the polynucleotidyl tr ansferase family. Thus, the Type 1 and Type 2 RNases H seem to share a comm on catalytic mechanism, except for the requirement of histidine as a genera l base in the former enzyme. Combined with the results from deletion mutant analyses, the structure suggests that the C-terminal domain of the Type 2 RNase H is involved in the interaction with the DNA/RNA hybrid.