M.BstF5I-2 and M.BstF5I-4 DNA Methyltransferases from BstF5I Restriction-Modification System of Bacillus stearothermophilus F5

V. A. Chernukhin², L. N. Golikova^1*, D. A. Gonchar², M. A. Abdurashitov², Yu. G. Kashirina³, N. A. Netesova¹, and S. Kh. Degtyarev²

¹State Research Center of Virology and Biotechnology “Vector”, Kol'tsovo 630559, Novosibirsk Region, Russia; fax: (383-2) 36-7409; E-mail: golikova@vector.nsc.ru

²Institute of Molecular Biology and Biophysics, Siberian Division, Russian Academy of Medical Sciences, ul. Timakova 9, Novosibirsk 630117, Russia; fax: (383-2) 33-6853; E-mail: abd@lae.ru

³SibEnzyme, ul. Timakova 9, Novosibirsk 630117, Russia; fax: (383-2) 33-6853; E-mail: kashirina@sibenzyme.ru

^* To whom correspondence should be addressed.

Received December 10, 2002

---

The BstF5I restriction-modification system from Bacillus stearothermophilus F5 includes four site-specific DNA methyltransferases, thus differing from all known restriction-modification systems. Here we demonstrated for the first time that one bacterial cell can possess two pairs of methylases with identical substrate specificities (methylases BstF5I-1 and BstF5I-3 recognize GGATG, whereas methylases BstF5I-2 and BstF5I-4 recognize CATCC) that modify adenine residues on both DNA strands. Different chromatographic methods provide homogenous preparations of methylases BstF5I-2 and BstF5I-4. We estimated the principal kinetic parameters of the reaction of transfer of methyl group from the donor S-adenosyl-L-methionine to the recognition site 5´-CATCC-3´ catalyzed by BstF5I-2 and BstF5I-4 DNA [N6-adenine]-methyltransferases from the BstF5I restriction-modification system.

---

KEY WORDS: DNA methyltransferase, restriction-modification system, Bacillus stearothermophilus, kinetics of an enzymatic reaction

---