Minnis J A, Taylor T E, Knesek J E, Peterson W L, McIntire S A
Biology Department, Texas Woman's University, Denton 76204, USA.
Plasmid. 1995 Jul;34(1):22-36. doi: 10.1006/plas.1995.1030.
A 3.5-kbp plasmid (pHPM180) was isolated from Helicobacter pylori (HPM180) and the DNA sequence was determined. Two open reading frames (ORF1 and ORF2) were identified which could encode polypeptides of 54,517 and 27,629 Da, respectively. Ribosome binding and promoter consensus sequences were identified, as well as two 232-bp direct repeats and four 22-bp direct repeats. DNA sequence homology was found between pHPM180 ORF1 and a 684-base pair HindIII fragment from a 5.6-kbp H. pylori plasmid. ORF1 showed amino acid homology with six replication proteins from bacterial plasmids with theta-type replicons. Additional sequence identity was found between pHPM180 noncoding DNA and a segment of H. pylori pHPK255, a plasmid that replicates via a rolling circle type mechanism. A ribonuclease protection assay determined that ORF1 was transcribed in H. pylori HPM180.
从幽门螺杆菌（HPM180）中分离出一个3.5千碱基对的质粒（pHPM180），并测定了其DNA序列。鉴定出两个开放阅读框（ORF1和ORF2），它们分别可编码54,517道尔顿和27,629道尔顿的多肽。确定了核糖体结合和启动子共有序列，以及两个232碱基对的直接重复序列和四个22碱基对的直接重复序列。在pHPM180的ORF1与来自一个5.6千碱基对幽门螺杆菌质粒的684碱基对HindIII片段之间发现了DNA序列同源性。ORF1与来自具有θ型复制子的细菌质粒的六种复制蛋白显示出氨基酸同源性。在pHPM180的非编码DNA与幽门螺杆菌pHPK255（一种通过滚环型机制复制的质粒）的一个片段之间发现了额外的序列同一性。核糖核酸酶保护试验确定ORF1在幽门螺杆菌HPM180中被转录。
