PRESTEADY STATE KINETICS OF AN S-ADENOSYLMETHIONINE-DEPENDENT ENZYME - EVIDENCE FOR A UNIQUE BINDING ORIENTATION REQUIREMENT FOR ECORI DNA METHYLTRANSFERASE

Citation
No. Reich et N. Mashhoon, PRESTEADY STATE KINETICS OF AN S-ADENOSYLMETHIONINE-DEPENDENT ENZYME - EVIDENCE FOR A UNIQUE BINDING ORIENTATION REQUIREMENT FOR ECORI DNA METHYLTRANSFERASE, The Journal of biological chemistry, 268(13), 1993, pp. 9191-9193
Citations number
13
Categorie Soggetti
Biology
ISSN journal
00219258
Volume
268
Issue
13
Year of publication
1993
Pages
9191 - 9193
Database
ISI
SICI code
0021-9258(1993)268:13<9191:PSKOAS>2.0.ZU;2-R
Abstract
We present the first presteady state kinetic analysis of an S-adenosyl methionine-dependent enzyme. The target enzyme is the bacterial EcoRI DNA methyltransferase, which transfers the methyl group to the second adenine in the DNA sequence GAATTC. The rate constant for conversion o f the central complex (enzyme-DNA-S-adenosylmethionine) to products (e nzyme-methylated DNA-S-adenosylhomocysteine) (41 +/- 7 s-1) is over 30 0-fold faster than k(cat), consistent with our demonstration that step s after methyl transfer are rate-limiting (Reich, N. O., and Mashhoon, N. (1991) Biochemistry 30,2933-2939). Methyl transfer at the N6 amino moiety of adenine on each strand requires a single binding orientatio n.