||MunI type II restriction/modification methylation reaction. MunI recognizes the sequence 5'-CAATTG-3' [PUB_0096]. MunI methylase methylates the N6 position of A-3 of hemimethylated DNA producing N6-methyladenine, and MunI endonuclease cleaves the C-A phosphodiester bond of unmethylated DNA in an ATP-independent manner [PUB_0006]. In constrant to type I restriction/modification systems, the methylase and endonuclease are two independent proteins. M. genitalium only contains the methylase of the MunI restriction/modification system.
Methylation occurs by transfer from S-Adenosyl-L-methionine [PUB_0458].
Jeltsch and colleagues have observed the methylation of type II restriction systems as a function of several parameters: 0.000059 - 0.079 1/h [PUB_0548], 0.34-3.9 [PUB_0549], 0.55-13 1/h [PUB_0550], 0.11-3.8 1/h [PUB_0551]. The rate limiting step is methyl group transfer. Under saturating S-Adenosyl-L-methionine conditions the kinetic rate rises to 3.9 1/h [PUB_0549], 3.8 1/h [PUB_0551].
Deutscher J, Saier MH Jr. ATP-dependent protein kinase-catalyzed phosphorylation of a seryl residue in HPr, a phosphate carrier protein of the phosphotransferase system in Streptococcus pyogenes. Proc Natl Acad Sci U S A 80, 6790-4 (1983). WholeCell: PUB_0458, PubMed: 6359157
Gowher H, Jeltsch A. Molecular enzymology of the EcoRV DNA-(Adenine-N (6))-methyltransferase: kinetics of DNA binding and bending, kinetic mechanism and linear diffusion of the enzyme on DNA. J Mol Biol 303, 93-110 (2000). WholeCell: PUB_0550, PubMed: 11021972
Jeltsch A, Christ F, Fatemi M, Roth M. On the substrate specificity of DNA methyltransferases. adenine-N6 DNA methyltransferases also modify cytosine residues at position N4. J Biol Chem 274, 19538-44 (1999). WholeCell: PUB_0548, PubMed: 10391886
Jeltsch A, Friedrich T, Roth M. Kinetics of methylation and binding of DNA by the EcoRV adenine-N6 methyltransferase. J Mol Biol 275, 747-58 (1998). WholeCell: PUB_0549, PubMed: 9480766
Keseler IM, Bonavides-Martínez C, Collado-Vides J, Gama-Castro S, Gunsalus RP, Johnson DA, Krummenacker M, Nolan LM, Paley S, Paulsen IT, Peralta-Gil M, Santos-Zavaleta A, Shearer AG, Karp PD. EcoCyc: a comprehensive view of Escherichia coli biology. Nucleic Acids Res 37, D464-70 (2009). WholeCell: PUB_0006, PubMed: 18974181
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