Kwong Stephen M, Skurray Ronald A, Firth Neville
School of Biological Sciences, University of Sydney, New South Wales 2006, Australia.
Mol Microbiol. 2004 Jan;51(2):497-509. doi: 10.1046/j.1365-2958.2003.03843.x.
The vast majority of large staphylococcal plasmids characterized to date appear to possess an evolutionarily common replication system, which has clearly had a major impact on the evolution of antimicrobial resistant staphylococci worldwide. Related systems have also been found in plasmids from other Gram-positive genera, including enterococci, streptococci and bacilli. The 46.4 kb plasmid pSK41 is the prototype of a family of conjugative staphylococcal multiresistance plasmids. The replication region of pSK41 encodes a protein product, Rep, which was shown to be essential for replication; mutations that truncated Rep could be complemented in trans. Rep was found to bind in vitro to four tandem repeat sequences located centrally within the rep coding region. An A + T-rich inverted repeat sequence upstream of rep was required for efficient replication, whereas no sequences downstream of rep were necessary. An antisense countertranscript, RNAI, encoded upstream of rep was identified and transcriptional start points for both RNAI and the rep-mRNA were defined.
迄今为止所鉴定的绝大多数大型葡萄球菌质粒似乎都拥有一个在进化上常见的复制系统，这显然对全球范围内耐抗菌药物葡萄球菌的进化产生了重大影响。在来自其他革兰氏阳性菌属（包括肠球菌、链球菌和芽孢杆菌）的质粒中也发现了相关系统。46.4 kb的质粒pSK41是接合型葡萄球菌多耐药性质粒家族的原型。pSK41的复制区域编码一种蛋白质产物Rep，已证明它对复制至关重要；截断Rep的突变可以通过反式互补。发现Rep在体外与位于rep编码区域中央的四个串联重复序列结合。rep上游富含A + T的反向重复序列是高效复制所必需的，而rep下游的序列则不是必需的。鉴定出了在rep上游编码的反义反转录本RNAI，并确定了RNAI和rep - mRNA的转录起始点。
