Stugard C E, Daskaleros P A, Payne S M
Department of Microbiology, University of Texas, Austin 78712.
Infect Immun. 1989 Nov;57(11):3534-9. doi: 10.1128/iai.57.11.3534-3539.1989.
The ability of Shigella flexneri to bind Congo red or hemin is associated with virulence. A 101-kilodalton (kDa) protein responsible for this phenotype (Crb+) in S. flexneri was identified by a tetramethylbenzidine staining procedure which detects heme-protein complexes in polyacrylamide gels. Labeling of cell-surface polypeptides with 125I revealed that the 101-kDa heme-binding protein is expressed on the cell surface. Expression of the protein was regulated by growth temperature and was found to be encoded by the large virulence plasmid of S. flexneri. Deletion mutants and a Tn5 insertion mutant which were negative for Congo red binding (Crb-) did not express the 101-kDa protein. Enteroinvasive Escherichia coli strains that were Crb+, and whose plasmids shared homology with the S. flexneri virulence plasmid, also expressed the 101-kDa protein. Expression of the protein in S. flexneri and enteroinvasive E. coli correlated with the presence of a 9.2-kilobase EcoRI fragment of these plasmids.
福氏志贺菌结合刚果红或血红素的能力与毒力相关。通过一种在聚丙烯酰胺凝胶中检测血红素 - 蛋白质复合物的四甲基联苯胺染色程序，鉴定出福氏志贺菌中负责这种表型（Crb +）的一种101千道尔顿（kDa）的蛋白质。用¹²⁵I标记细胞表面多肽表明，101-kDa血红素结合蛋白在细胞表面表达。该蛋白质的表达受生长温度调节，并且发现由福氏志贺菌的大毒力质粒编码。刚果红结合呈阴性（Crb -）的缺失突变体和Tn5插入突变体不表达101-kDa蛋白质。Crb +且其质粒与福氏志贺菌毒力质粒具有同源性的侵袭性大肠杆菌菌株也表达101-kDa蛋白质。福氏志贺菌和侵袭性大肠杆菌中该蛋白质的表达与这些质粒的一个9.2千碱基的EcoRI片段的存在相关。
