Edwards Robert A, Matlock Brian C, Heffernan Brian J, Maloy Stanley R
Department of Microbiology, University of Illinois, Urbana, IL 61801, USA1.
Microbiology (Reading). 2001 Oct;147(Pt 10):2705-2715. doi: 10.1099/00221287-147-10-2705.
Salmonella enterica serovar Enteritidis is a leading cause of food poisoning in the USA and Europe. Although Salmonella serovars share many fimbrial operons, a few fimbriae are limited to specific Samonella serovars. SEF14 fimbriae are restricted to group D Salmonella and the genes encoding this virulence factor were acquired relatively recently. Genomic, genetic and gene expression studies have been integrated to investigate the ancestry, regulation and expression of the sef genes. Genomic comparisons of the Salmonella serovars sequenced revealed that the sef operon is inserted in leuX in Salmonella Enteritidis, Salmonella Paratyphi and Salmonella Typhi, and revealed the presence of a previously unidentified 25 kb pathogenicity island in Salmonella Typhimurium at this location. Salmonella Enteritidis contains a region of homology between the Salmonella virulence plasmid and the chromosome downstream of the sef operon. The sef operon itself consists of four co-transcribed genes, sefABCD, and adjacent to sefD there is an AraC-like transcriptional activator that is required for expression of the sef genes. Expression of the sef genes was optimal during growth in late exponential phase and was repressed during stationary phase. The regulation was coordinated by the RpoS sigma factor.
肠炎沙门氏菌肠炎血清型是美国和欧洲食物中毒的主要原因。尽管沙门氏菌血清型共享许多菌毛操纵子，但少数菌毛仅限于特定的沙门氏菌血清型。SEF14菌毛仅限于D组沙门氏菌，编码这种毒力因子的基因是最近才获得的。基因组、遗传学和基因表达研究已整合起来，以研究sef基因的起源、调控和表达。对已测序的沙门氏菌血清型进行基因组比较发现，sef操纵子插入肠炎沙门氏菌、甲型副伤寒沙门氏菌和伤寒沙门氏菌的leuX中，并揭示了鼠伤寒沙门氏菌在该位置存在一个以前未鉴定的25 kb致病岛。肠炎沙门氏菌在沙门氏菌毒力质粒和sef操纵子下游的染色体之间含有一个同源区域。sef操纵子本身由四个共转录基因sefABCD组成，在sefD附近有一个AraC样转录激活因子，sef基因的表达需要该因子。sef基因在指数生长后期的表达最佳，在稳定期受到抑制。这种调控由RpoSσ因子协调。
