Department of Microbiology, Oslo University Hospital and University of Oslo, P.O. Box 4950 Nydalen, 0424 Oslo, Norway.
J Struct Biol. 2013 Jul;183(1):66-75. doi: 10.1016/j.jsb.2013.04.007. Epub 2013 Apr 25.
The recently discovered HEAT-like repeat (HLR) DNA glycosylase superfamily is widely distributed in all domains of life. The present bioinformatics and phylogenetic analysis shows that HLR DNA glycosylase superfamily members in the genus Bacillus form three subfamilies: AlkC, AlkD and AlkF/AlkG. The crystal structure of AlkF shows structural similarity with the DNA glycosylases AlkC and AlkD, however neither AlkF nor AlkG display any DNA glycosylase activity. Instead, both proteins have affinity to branched DNA structures such as three-way and Holliday junctions. A unique β-hairpin in the AlkF/AlkG subfamily is most likely inserted into the DNA major groove, and could be a structural determinant regulating DNA substrate affinity. We conclude that AlkF and AlkG represent a new family of HLR proteins with affinity for branched DNA structures.
最近发现的热激样重复（HLR）DNA 糖苷酶超家族广泛分布于所有生命领域。目前的生物信息学和系统发育分析表明，芽孢杆菌属中的 HLR DNA 糖苷酶超家族成员形成三个亚家族：AlkC、AlkD 和 AlkF/AlkG。AlkF 的晶体结构与 DNA 糖苷酶 AlkC 和 AlkD 具有结构相似性，但 AlkF 和 AlkG 均不显示任何 DNA 糖苷酶活性。相反，这两种蛋白质都与分支 DNA 结构（如三链和 Holliday 连接）具有亲和力。AlkF/AlkG 亚家族中的一个独特的β发夹很可能插入到 DNA 大沟中，并且可能是调节 DNA 底物亲和力的结构决定因素。我们得出结论，AlkF 和 AlkG 代表了一个具有分支 DNA 结构亲和力的 HLR 蛋白新家族。
