Function of Pro‐185 in the ProCys of conserved motif IV in the EcoRII [cytosine‐C5]‐DNA methyltransferase

FEBS Letters

Hattman, Stanley¹  Kossykh, Valeri G.¹  Schlagman, Samuel L.¹ 

[1] Department of Biology, University of Rochester, Rochester, NY 14627, USA

关键词: Amino acid homology;    DNA methylation;    5-methylcytosine;    Catalysis;    aa;    amino acid;    MTase;    methyltransferase;    AdoMet;    Cyt;    cytosine;   

DOI  :  10.1016/0014-5793(95)00795-B

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

ProCys in the conserved sequence motif IV of [cytosine-C5]-DNA methyltransferases is known to be part of the catalytic site. The Cys residue is directly involved in forming a covalent bond with the C6 of the target cytosine. We have found that substitution of Pro-185 with either Ala or Ser resulted in a reduced rate of methyl group transfer by the EcoRII DNA methyltransferase. In addition, we observed an increase in the K _m for substrate (AdoMet), but a decrease in the K _m for substrate DNA. This is reflected in minor changes in k _cat/K _m for DNA, but in 10- to 100-fold reductions in k _cat/K _m for AdoMet. This suggests that Pro-185 is important to properly orient the activated cytosine and AdoMet for methyl group transfer by direct interaction with AdoMet and indirectly via the Cys interaction with cytosine.

【 授权许可】

Unknown