Stenson Trevor H, Patton Angela K, Weiss Alison A
Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati, Cincinnati, Ohio 45267-0524, USA.
Infect Immun. 2003 Mar;71(3):1316-20. doi: 10.1128/IAI.71.3.1316-1320.2003.
The abilities of cysteine-containing compounds to support growth of Bordetella pertussis and influence pertussis toxin transcription, assembly, and secretion were examined. Cysteine is an essential amino acid for B. pertussis and must be present for protein synthesis and bacterial growth. However, cysteine can be metabolized to sulfate, and high concentrations of sulfate can selectively inhibit transcription of the virulence factors, including pertussis toxin, via the BvgAS two-component regulatory system in a process called modulation. In addition, pertussis toxin possesses several disulfide bonds, and the cysteine-containing compound glutathione can influence oxidation-reduction reactions and perhaps disulfide bond formation. Bacterial growth was not observed in the absence of a source of cysteine. Oxidized glutathione, as a sole source of cysteine, also did not support bacterial growth. Cysteine, cystine, and reduced glutathione did support bacterial growth, and none of these compounds caused modulation at the concentrations tested. Similar amounts of periplasmic pertussis toxin were detected regardless of the source of cysteine; however, in the absence of reduced glutathione, pertussis toxin was not efficiently secreted. Addition of the reducing agent dithiothreitol was unable to compensate for the lack of reduced glutathione and did not promote secretion of pertussis toxin. These results suggest that reduced glutathione does not affect the accumulation of assembled active pertussis toxin in the periplasm but plays a role in efficient pertussis toxin secretion by the bacterium.
研究了含半胱氨酸的化合物支持百日咳博德特氏菌生长以及影响百日咳毒素转录、组装和分泌的能力。半胱氨酸是百日咳博德特氏菌的必需氨基酸，蛋白质合成和细菌生长都必须有半胱氨酸存在。然而，半胱氨酸可代谢为硫酸盐，高浓度的硫酸盐可通过BvgAS双组分调节系统在一个称为调节的过程中选择性抑制包括百日咳毒素在内的毒力因子的转录。此外，百日咳毒素含有多个二硫键，含半胱氨酸的化合物谷胱甘肽可影响氧化还原反应，或许还能影响二硫键的形成。在没有半胱氨酸来源的情况下未观察到细菌生长。氧化型谷胱甘肽作为半胱氨酸的唯一来源，也不能支持细菌生长。半胱氨酸、胱氨酸和还原型谷胱甘肽确实能支持细菌生长，并且在测试浓度下这些化合物均未引起调节作用。无论半胱氨酸来源如何，检测到的周质百日咳毒素量相似；然而，在没有还原型谷胱甘肽的情况下，百日咳毒素不能有效分泌。添加还原剂二硫苏糖醇无法弥补还原型谷胱甘肽的缺乏，也不能促进百日咳毒素的分泌。这些结果表明，还原型谷胱甘肽不影响周质中组装好的活性百日咳毒素的积累，但在细菌有效分泌百日咳毒素中起作用。
