Somkuti G A, Solaiman D K, Steinberg D H
Agricultural Research Service, U.S. Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, Pennsylvania, 19038, USA.
Plasmid. 1998 Jul;40(1):61-72. doi: 10.1006/plas.1998.1352.
The plasmid pER341 (2798 bp) of Streptococcus thermophilus ST134 was sequenced and its open reading frame (ORF) regions were characterized. Analysis of nucleotide sequences showed the putative translation product of ORF1 (rep) sharing a high level of homology with replication proteins of several small plasmids present in lactic acid bacteria and staphylococci. This and homology of regions of plus-strand (ORI) and minus-strand (ssoA) origin of replication with pC194-class plasmids indicated that pER341 replicates by the rolling-circle mechanism. ORF2 corresponded to a putative hsp gene that apparently encodes Hsp16.4, a 142-amino-acid heat stress protein. Hsp16.4 shared significant identity with other small, 18-kDa-class heat stress proteins from prokaryotic and eukaryotic sources. Hsp16.4 is apparently the first plasmidborne low-molecular-weight heat stress protein reported in dairy fermentation bacteria with a potential role in temperature-regulated functions in S. thermophilus.
对嗜热链球菌ST134的质粒pER341（2798 bp）进行了测序，并对其开放阅读框（ORF）区域进行了特征分析。核苷酸序列分析表明，ORF1（rep）的推定翻译产物与乳酸菌和葡萄球菌中存在的几种小质粒的复制蛋白具有高度同源性。这以及正链（ORI）和负链（ssoA）复制起点区域与pC194类质粒的同源性表明，pER341通过滚环机制进行复制。ORF2对应于一个推定的hsp基因，该基因显然编码Hsp16.4，一种142个氨基酸的热应激蛋白。Hsp16.4与来自原核和真核来源的其他18 kDa类小热应激蛋白具有显著的同一性。Hsp16.4显然是首次在乳制品发酵细菌中报道的质粒携带的低分子量热应激蛋白，可能在嗜热链球菌的温度调节功能中发挥作用。
