Kulaeva O I, Koonin E V, McDonald J P, Randall S K, Rabinovich N, Connaughton J F, Levine A S, Woodgate R
Section on DNA Replication, Repair and Mutagenesis, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-2725, USA.
Mutat Res. 1996 Oct 25;357(1-2):245-53. doi: 10.1016/0027-5107(96)00164-9.
To date, eight closely related homologs of the Escherichia coli UmuC protein have been identified. All of these homologs appear to play critical roles in damage-inducible mutagenesis in enterobacteriaceae. Recently, a distantly related UmuC-homolog, DinB, has also been identified in E. coli. Using the polymerase chain reaction together with degenerate primers designed against conserved regions found in UmuC-like proteins, we have identified a new member of the UmuC-superfamily in the archeon Sulfolobus solfataricus. This new homolog shows high sequence similarity to DinB and a lower level of similarity to UmuC. As a consequence, we have called this new gene dbh (dinB homolog). Analysis of approximately 2.7 kb DNA encompassing the dbh region revealed several open reading frames (orfs). One, encoding a putative ribokinase, was located immediately upstream of dbh. This orf overlaps the dbh gene by 4 bp suggesting that both proteins might be coordinately expressed. Further upstream of the ribokinase-dbh locus was another orf encoding a potential ATPase homologous to two uncharacterized S. cerevisiae proteins (YD9346.02c and SC38KCXVI_20) and another E. coli DNA repair protein, RuvB. While this is the first report of a UmuC-like homolog in an archeon, we detected additional homologs using protein sequence comparisons in Gram-positive bacteria, cyanobacteria, and among potential human EST products, indicating that UmuC-related proteins comprise a ubiquitous superfamily of proteins probably involved in DNA repair and mutagenesis.
迄今为止，已鉴定出8种与大肠杆菌UmuC蛋白密切相关的同源物。所有这些同源物似乎在肠杆菌科的损伤诱导型诱变中发挥关键作用。最近，在大肠杆菌中还鉴定出一种亲缘关系较远的UmuC同源物DinB。利用聚合酶链反应以及针对UmuC样蛋白中保守区域设计的简并引物，我们在古菌嗜热栖热菌中鉴定出UmuC超家族的一个新成员。这个新的同源物与DinB具有高度的序列相似性，与UmuC的相似性较低。因此，我们将这个新基因命名为dbh（DinB同源物）。对包含dbh区域的约2.7 kb DNA进行分析，发现了几个开放阅读框（ORF）。其中一个编码假定的核糖激酶，位于dbh的紧邻上游。这个ORF与dbh基因重叠4个碱基对，表明这两种蛋白质可能是协同表达的。在核糖激酶-dbh基因座的更上游是另一个ORF，它编码一种潜在的ATP酶，与两种未鉴定的酿酒酵母蛋白（YD9346.02c和SC38KCXVI_20）以及另一种大肠杆菌DNA修复蛋白RuvB同源。虽然这是首次在古菌中报道UmuC样同源物，但我们通过蛋白质序列比较在革兰氏阳性细菌、蓝细菌以及潜在的人类EST产物中检测到了其他同源物，这表明UmuC相关蛋白构成了一个普遍存在的超家族，可能参与DNA修复和诱变。
