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Restriction and modification in Bacillus subtilis: two DNA methyltransferases with BsuRI specificity. II. Catalytic properties, substrate specificity, and mode of action

Günthert, U. and Jentsch, S. and Freund, M.. (1981) Restriction and modification in Bacillus subtilis: two DNA methyltransferases with BsuRI specificity. II. Catalytic properties, substrate specificity, and mode of action. Journal of biological chemistry, 256 (17). pp. 9346-9351.

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Official URL: http://edoc.unibas.ch/dok/A5249260

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Abstract

The properties of two DNA methyltransferases, termed M. BsuRIa and M. BsuRIb, whose isolation was described in the preceding paper (Günthert, U., Freund, M., and Trautner, T. A. (1981) J. Biol. Chem. 256, 9340-9345) were compared. Both enzymes recognize the same target sequence in double-stranded DNA, leading to methylation of the internal cytosine: 5'GGCC. The enzymes have identical reaction constants with their substrates, DNA (km = 2.7 nM for the 5' GGCC sequence), and S-adenosyl-L-methionine (km = 0.7 microM). Initial rates of methyl group transfer were proportional to enzyme concentration over a range of 50-fold, indicating absence of aggregation. The enzymes are different in their ionic strength requirements using Tris-HCl, pH 8.4. M. BsuRIa is most active at 100 mM, M. BsuRIb at 440 mM. As measured by incorporation kinetics and heat inactivation, M. BsuRIa is the more stable enzyme of the two. Equilibrium dialysis was used to study the mode of methyl group transfer to the DNA with either enzyme. The data indicate that initially S-adenosyl-L-methionine binds to methyltransferase. This complex attaches to either modified or nonmodified DNA. The methyl group will then be transferred to a nonmodified target sequence, leading to the dissociation of enzyme and S-adenosyl-L-homocysteine from the DNA.
Faculties and Departments:03 Faculty of Medicine > Bereich Querschnittsfächer (Klinik) > Ehemalige Einheiten Querschnittsfächer (Klinik) > Allgemeine und spezielle Pathologie (Oberholzer)
03 Faculty of Medicine > Departement Klinische Forschung > Bereich Querschnittsfächer (Klinik) > Ehemalige Einheiten Querschnittsfächer (Klinik) > Allgemeine und spezielle Pathologie (Oberholzer)
03 Faculty of Medicine > Bereich Querschnittsfächer (Klinik) > Pathologie USB > Allgemeine Pathologie (Tolnay)
03 Faculty of Medicine > Departement Klinische Forschung > Bereich Querschnittsfächer (Klinik) > Pathologie USB > Allgemeine Pathologie (Tolnay)
03 Faculty of Medicine > Bereich Querschnittsfächer (Klinik) > Pathologie USB > Neuro- und Muskelpathologie (Frank)
03 Faculty of Medicine > Departement Klinische Forschung > Bereich Querschnittsfächer (Klinik) > Pathologie USB > Neuro- und Muskelpathologie (Frank)
UniBasel Contributors:Günthert, Ursula
Item Type:Article, refereed
Article Subtype:Research Article
Bibsysno:Link to catalogue
Publisher:American Society of Biological Chemists
ISSN:0021-9258
Note:Publication type according to Uni Basel Research Database: Journal article
Language:English
Last Modified:27 Sep 2017 10:07
Deposited On:22 Mar 2012 13:34

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