ROS1 5-methylcytosine DNA glycosylase is a slow-turnover catalyst that initiates DNA demethylation in a distributive fashion.
ROS1 5-methylcytosine DNA glycosylase is a slow-turnover catalyst that initiates DNA demethylation in a distributive fashion.
复制标题
DOI：
10.1093/nar/gkp390
复制
发表时间：
2009-07
影响因子：
14.9
通讯作者：
Ariza RR
中科院分区：
文献类型：
--
作者：
Ponferrada-Marín MI;Roldán-Arjona T;Ariza RR
拟南芥ROS1属于植物5-甲基胞嘧啶DNA糖基酶家族，通过碱基切除启动DNA去甲基化。ROS1表现出显著的切割5-MEC和较小程度T的能力，同时保留了有效识别C和U的能力。我们发现，用卤素取代C5-甲基大大降低了目标碱基的切割。此外，5-MEC在错配中被更有效地切除，而T仅在与G错配时才被切除。这些结果表明，ROS1的特异性是由活性部位的选择性识别和靶碱基的热力学稳定性相结合而产生的。我们还发现，ROS1是一种低转化率的催化剂，因为它与5-MEC去除后留下的碱性中心紧密结合。这种结合导致了酶在含有多个5-MEC残基的DNA底物上的高度分布行为，并可能有助于避免在双甲基化CG二核苷酸加工过程中产生双链断裂。我们的结论是，ROS1的生化特性与其在保护植物基因组免受过度甲基化方面的作用是一致的。
Arabidopsis ROS1 belongs to a family of plant 5-methycytosine DNA glycosylases that initiate DNA demethylation through base excision. ROS1 displays the remarkable capacity to excise 5-meC, and to a lesser extent T, while retaining the ability to discriminate effectively against C and U. We found that replacement of the C5-methyl group by halogen substituents greatly decreased excision of the target base. Furthermore, 5-meC was excised more efficiently from mismatches, whereas excision of T only occurred when mispaired with G. These results suggest that ROS1 specificity arises by a combination of selective recognition at the active site and thermodynamic stability of the target base. We also found that ROS1 is a low-turnover catalyst because it binds tightly to the abasic site left after 5-meC removal. This binding leads to a highly distributive behaviour of the enzyme on DNA substrates containing multiple 5-meC residues, and may help to avoid generation of double-strand breaks during processing of bimethylated CG dinucleotides. We conclude that the biochemical properties of ROS1 are consistent with its proposed role in protecting the plant genome from excess methylation.
登录
查看更多内容
影响因子：
2.9
作者：
Carey, DC;Strauss, PR
通讯作者：
Strauss, PR
影响因子：
2.9
作者：
Krishnamurthy, Nirmala;Haraguchi, Kazuhiro;David, Sheila S.
通讯作者：
David, Sheila S.
DOI：
10.1046/j.1432-1327.1999.00819.x
发表时间：
1999-11-01
期刊：
EUROPEAN JOURNAL OF BIOCHEMISTRY
影响因子：
--
作者：
Marcourt, L;Cordier, C;Dodin, G
通讯作者：
Dodin, G
影响因子：
14.9
作者：
Hardeland, U;Bentele, M;Schär, P
通讯作者：
Schär, P
DOI：
10.1073/pnas.0603563103
发表时间：
2006-08-01
影响因子：
11.1
作者：
Agius, Fernanda;Kapoor, Avnish;Zhu, Jian-Kang
通讯作者：
Zhu, Jian-Kang