A bipolar DNA helicase gene, herA, clusters with rad50, mre11 and nurA genes in thermophilic archaea
A bipolar DNA helicase gene, herA, clusters with rad50, mre11 and nurA genes in thermophilic archaea
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DOI：
10.1093/nar/gkh283
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发表时间：
2004-02-01
影响因子：
14.9
通讯作者：
Elie, C
中科院分区：
文献类型：
--
作者：
Constantinesco, F;Forterre, P;Elie, C
我们以前表明，rad 50和mre 11基因的嗜热古菌的操纵子样结构与第三个基因（nurA）编码的5'到3'核酸外切酶。在这里，我们表明，rad 50，mre 11和nurA基因的嗜热古菌硫化叶菌acidocaldarius共转录与第四个基因编码的DNA解旋酶。这种酶（HerA）是一类新的DNA解旋酶的原型，其能够利用3'或5'单链DNA延伸进行装载和随后的DNA双链体解旋。据我们所知，能够沿DNA在两个方向上沿着易位的DNA解旋酶以前尚未被鉴定。HerA基因的序列分析表明它是PilT类NTPases的TrwB、FtsK和VirB 4/VirD 4家族的成员。HerA同源物存在于所有嗜热古菌物种中，并且在除一种之外的所有情况下，rad 50、mre 11、nurA和herA基因被分组在一起。这些结果表明，古细菌Rad 50-Mre 11复合物可能与5'至3'核酸外切酶（NurA）和双极DNA解旋酶（HerA）联合作用，表明可能参与同源重组的起始步骤。
We showed previously that rad50 and mre11 genes of thermophilic archaea are organized in an operon-like structure with a third gene (nurA) encoding a 5' to 3' exonuclease. Here, we show that the rad50, mre11 and nurA genes from the hyperthermo philic archaeon Sulfolobus acidocaldarius are co-transcribed with a fourth gene encoding a DNA helicase. This enzyme (HerA) is the prototype of a new class of DNA helicases able to utilize either 3' or 5' single-stranded DNA extensions for loading and subsequent DNA duplex unwinding. To our knowledge, DNA helicases capable of translocating along the DNA in both directions have not been identified previously. Sequence analysis of HerA shows that it is a member of the TrwB, FtsK and VirB4/VirD4 families of the PilT class NTPases. HerA homologs are found in all thermophilic archaeal species and, in all cases except one, the rad50, mre11, nurA and herA genes are grouped together. These results suggest that the archaeal Rad50-Mre11 complex might act in association with a 5' to 3' exonuclease (NurA) and a bipolar DNA helicase (HerA) indicating a probable involvement in the initiation step of homologous recombination.