The enzymatic activities of the Werner syndrome protein are disabled by the amino acid polymorphism R834C
The enzymatic activities of the Werner syndrome protein are disabled by the amino acid polymorphism R834C
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DOI：
10.1074/jbc.m407128200
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发表时间：
2004-12-31
影响因子：
4.8
通讯作者：
Loeb, LA
中科院分区：
文献类型：
--
作者：
Kamath-Loeb, AS;Welcsh, P;Loeb, LA
Werner综合征蛋白（WRN）是RecQ DNA解旋酶家族的成员。它同时具有3' ->5' DNA解旋酶和3' ->5' DNA外切核酸酶活性。WRN突变与一种罕见的隐性疾病Werner综合征（WS）有因果关系，其特征是过早衰老和基因组不稳定;据报道，所有这些都导致蛋白质表达丧失。除了WS连锁突变，单核苷酸多态性，频率超过WS相关突变，也存在于WRN。我们已经开始研究，以确定这些多态性中的六个是否影响WRN的酶活性。我们发现，两个常见的多态性，F1074 L和C1367 R，和两个罕见的多态性，Q724 L和S1079 L，表现出相对于野生型WRN的活性变化不大;多态性，T172 P，表现出一个小的，但一致的活动减少。然而，一个罕见的多态性，R834 C，位于解旋酶结构域显着降低WRN解旋酶和解旋酶偶联核酸外切酶的活性。对E.大肠杆菌解旋酶核心提示R834可能参与与ATP的相互作用。正如所预测的，用Cys取代Arg干扰解旋DNA绝对需要的ATP水解。因此，R834 C代表WRN中的第一个错义氨基酸多态性，其几乎消除酶活性，同时使表达基本上不受影响。
The Werner syndrome protein, WRN, is a member of the RecQ family of DNA helicases. It possesses both 3' -->5' DNA helicase and 3' -->5' DNA exonuclease activities. Mutations in WRN are causally associated with a rare, recessive disorder, Werner syndrome (WS), distinguished by premature aging and genomic instability; all are reported to result in loss of protein expression. In addition to WS-linked mutations, single nucleotide polymorphisms, with frequencies that exceed those of WS-associated mutations, are also present in WRN. We have initiated studies to determine if six of these polymorphisms affect the enzymatic activities of WRN. We show that two common polymorphisms, F1074L and C1367R, and two infrequent polymorphisms, Q724L and S1079L, exhibit little change in activity relative to wild-type WRN; the polymorphism, T172P, shows a small but consistent reduction of activity. However, an infrequent polymorphism, R834C, located in the helicase domain dramatically reduces WRN helicase and helicase-coupled exonuclease activity. The structure of the E. coli helicase core suggests that R834 may be involved in interactions with ATP. As predicted, substitution of Arg with Cys interferes with ATP hydrolysis that is absolutely required for unwinding DNA. R834C thus represents the first missense amino acid polymorphism in WRN that nearly abolishes enzymatic activity while leaving expression largely unaffected.