Passerini de Rossi B N, Friedman L E, Darnaud S, de Torres R A, Franco M A
Cátedra de Microbiología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina.
Vet Microbiol. 1997 May;56(1-2):65-77. doi: 10.1016/S0378-1135(97)00078-3.
The bvg or vir locus positively regulates the expression of many Bordetella virulence-associated determinants (encoded by vag genes), including cell envelope proteins, in response to environmental stimuli. On the other hand, several genes named vrg genes are negatively controlled by the bvg regulon (Knapp and Mekalanos, 1988). Flagellin is encoded by a vrg gene, which is expressed when the principal virulence factors are eliminated during antigenic modulation or in phase variants (Akerley et al., 1992). We have previously analyzed SDS-PAGE profiles of Sarkosyl-outer membrane protein (OMP)-enriched fractions from B. bronchiseptica Bvg- and modulated Bvg+ strains and reported a major band associated with the avirulent phenotype (Passerini de Rossi et al., 1995). In order to characterize this band we have purified flagellar filaments from Bvg- and modulated Bvg+ strains, and analyzed them by SDS-PAGE. These profiles revealed a single major band of 40 or 45 kDa depending on the strain. The N-terminal amino acid sequence of the putative flagellin expressed by BB7200a was identical over the first 21 residues analyzed to that of the flagellin from the modulated strain BB7865 reported by Akerley et al. (1992). Comparison of the SDS-PAGE profile of flagellar filaments with that of the OMP-enriched fraction of the corresponding strain showed that the flagellum-associated polypeptide had the same electrophoretic mobility as that of the characteristic band of the avirulent phenotype. Furthermore, this band was absent in the OMP-enriched fraction profile from a Bvg- strain subjected to a treatment that removes flagella. Our results indicate that the major protein observed in SDS-PAGE profiles of Sarkosyl-OMP-enriched fractions from B. bronchiseptica Bvg- and modulated Bvg+ strains corresponds to flagellin.
bvg或vir位点可响应环境刺激，正向调控许多与博德特氏菌毒力相关的决定因素（由vag基因编码）的表达，包括细胞包膜蛋白。另一方面，几个名为vrg基因的基因受到bvg调控子的负调控（克纳普和梅卡洛诺斯，1988年）。鞭毛蛋白由一个vrg基因编码，当主要毒力因子在抗原调节或相位变体中被消除时表达（阿克利等人，1992年）。我们之前分析了支气管败血博德特氏菌Bvg-和调节后的Bvg+菌株中富含十二烷基肌氨酸钠-外膜蛋白（OMP）的组分的SDS-PAGE图谱，并报道了一条与无毒表型相关的主要条带（帕塞里尼·德罗西等人，1995年）。为了表征这条条带，我们从Bvg-和调节后的Bvg+菌株中纯化了鞭毛丝，并通过SDS-PAGE进行分析。这些图谱显示，根据菌株不同，有一条40或45 kDa的单一主要条带。BB7200a表达的假定鞭毛蛋白的N端氨基酸序列在前21个分析残基上与阿克利等人（1992年）报道的调节后菌株BB7865的鞭毛蛋白相同。将鞭毛丝的SDS-PAGE图谱与相应菌株富含OMP的组分的图谱进行比较，结果表明与鞭毛相关的多肽具有与无毒表型特征条带相同的电泳迁移率。此外，在经过去除鞭毛处理的Bvg-菌株的富含OMP的组分图谱中没有这条条带。我们的结果表明，在支气管败血博德特氏菌Bvg-和调节后的Bvg+菌株的富含十二烷基肌氨酸钠-OMP的组分的SDS-PAGE图谱中观察到的主要蛋白质对应于鞭毛蛋白。
