Salmonella enteritidis agfBAC operon encoding thin, aggregative fimbriae
Salmonella enteritidis agfBAC operon encoding thin, aggregative fimbriae
复制标题
DOI：
10.1128/jb.178.3.662-667.1996
复制
发表时间：
1996-02-01
影响因子：
3.2
通讯作者：
Kay, WW
中科院分区：
文献类型：
--
作者：
Collinson, SK;Clouthier, SC;Kay, WW
肠炎沙门氏菌产生薄的、聚集的菌毛，称为 SEF17，由聚合的 AgfA 菌毛蛋白组成。对肠炎沙门氏菌 DNA 2 kb 区域的 DNA 序列分析揭示了三个连续的基因 agfBAC。 453 bp agfA 基因编码 AgfA 菌毛蛋白，预计其一级序列与大肠杆菌 curli 结构蛋白 CsgA 具有 74% 相同性和 86% 相似性。 pH;IG 是一种 pUC18 衍生物，含有编码 agfBAC 的 3.0-kb HindIII 片段，指导主要 AgfA 菌毛蛋白（M(r) 为 17,000）和次要 AgfB 蛋白（M(r) 为 16,000，由 453-bp agfB 基因编码）的体外表达。 AgfA 不由 pDAG 表达，pDAG 是一种 pUC18 衍生物，包含编码 agfA 但不编码 agfB 的 3.1-kb DraI DNA 片段。引物延伸分析鉴定出两个相邻的转录起始位点，位于agfB的紧上游，其位置类似于大肠杆菌curlin csgBA操纵子的位置。 agfA 或 agfC 的上游没有转录起始位点。 Northern (RNA) 印迹分析证实 agfA 的转录是从 agfB 启动子区域起始的。对 agfBAC 假定的 mRNA 转录本的二级结构分析预测，在 agfA 和 agfC 之间的顺反子间区域会形成茎环结构（Delta G(o)，-22 kcal/mol [-91 kJ/mol]），这可能与 agfBAC 转录本的 agfBA 部分的稳定有关。 agfBAC 和侧翼区域与可获得序列数据的大肠杆菌curlin csgBA 区域的对应区域具有高度的序列相似性。这些数据表明肠炎沙门氏菌SEF17菌毛和大肠杆菌卷曲菌在菌毛蛋白氨基酸序列和遗传组织方面具有高度相似性，因此表明它们具有共同且相对较新的祖先。
Salmonella enteritidis produces thin, aggregative fimbriae, named SEF17, which are composed of polymerized AgfA fimbrin proteins. DNA sequence analysis of a 2-kb region of S. enteritidis DNA revealed three contiguous genes, agfBAC. The 453-bp agfA gene encodes the AgfA fimbrin, which was predicted to be 74% identical and 86% similar in primary sequence to the Escherichia coli curli structural protein, CsgA. pH;IG, a pUC18 derivative containing a 3.0-kb HindIII fragment encoding agfBAC, directed the in vitro expression of the major AgfA fimbrin, with an M(r) of 17,000, and a minor AgfB protein, with an M(r) of 16,000, encoded by the 453-bp agfB gene. AgfA was not expressed from pDAG, a pUC18 derivative containing a 3.1-kb DraI DNA fragment encoding agfA but not agfB. Primer extension analysis identified two adjacent transcription start sites located immediately upstream of agfB in positions analogous to those of the E. coli curlin csgBA operon. No transcription start sites were located immediately upstream of agfA or agfC. Northern (RNA) blot analysis confirmed that transcription of agfA was initiated from the agfB promoter region. Secondary-structure analysis of the putative mRNA transcript for agfBAC predicted the formation of a stem-loop structure (Delta G(o), -22 kcal/mol [-91 kJ/mol]) in the intercistronic region between agfA and agfC, which may be involved in stabilization of the agfBA portion of the agfBAC transcript. agfBAC and flanking regions had a high degree of sequence similarity with those counterparts of the E. coli curlin csgBA region for which sequence data are available. These data are demonstrative of the high degree of similarity between S. enteritidis SEF17 fimbriae and E. coli curli with respect to fimbrin amino acid sequence and genetic organization and, therefore, are indicative of a common and relatively recent ancestry.