Keeling P J, Klenk H P, Singh R K, Feeley O, Schleper C, Zillig W, Doolittle W F, Sensen C W
Department of Biochemistry, Dalhousie University, Halifax, Nova Scotia, Canada.
Plasmid. 1996 Mar;35(2):141-4. doi: 10.1006/plas.1996.0016.
The complete sequence of the 5350-bp plasmid pRN1 from the crenarchaeote Sulfolobus islandicus has been determined. This plasmid is the first to be sequenced from this group of thermoacidophilic archaebacteria (Archaea) and its high copy number and wide host range make it a good candidate for a cloning vector. pRN1 contains several open reading frames, including one that spans over half the plasmid and has significant similarity to the helicase domain of viral primase proteins. Directly upstream of this putative primase is a homologue of Cop, a family of small proteins from promiscuous eubacterial plasmids which control copy number by repressing the expression of the replication initiation protein. In eubacterial plasmids cop is found upstream of the replication initiator protein. The location of a cop homologue upstream of a primase-like gene in pRN1 suggests that it controls DNA replication in a manner similar to these eubacterial plasmids, but does so using a mixture of components from plasmids and viruses.
已确定来自嗜热嗜酸古细菌硫磺岛硫化叶菌的5350碱基对质粒pRN1的完整序列。该质粒是从这组嗜热嗜酸古细菌（古菌）中第一个被测序的，其高拷贝数和广泛的宿主范围使其成为克隆载体的良好候选者。pRN1包含几个开放阅读框，其中一个跨越质粒的一半以上，与病毒引发酶蛋白的解旋酶结构域具有显著相似性。在这个假定的引发酶的直接上游是Cop的同源物，Cop是一类来自混杂真细菌质粒的小蛋白家族，通过抑制复制起始蛋白的表达来控制拷贝数。在真细菌质粒中，cop位于复制起始蛋白的上游。pRN1中cop同源物位于类引发酶基因上游的位置表明，它以类似于这些真细菌质粒的方式控制DNA复制，但使用的是来自质粒和病毒的成分混合物。
