The Salmonella enterica serovar Typhi genome contains 14 putative fimbrial systems. The Std fimbriae belong to the chaperone-usher family and its regulation has not been investigated in S. Typhi. Several regulators of Std were previously identified in the closely related serovar Typhimurium. We hypothesize that regulators of S. Typhimurium may be shared with S. Typhi, but that several other regulators remain to be discovered. Here, we describe the role of more than 50 different candidate regulators on std expression. Three types of regulators were investigated: known regulators in S. Typhimurium, in silico predicted regulators and virulence/metabolic regulators. Expression of std was determined in the regulator mutants and compared with the wild-type strain. Overall, 21 regulator mutations affect std promoter expression. The role of Crp, a newly identified factor for std expression, was further investigated. Crp acted as an activator of std expression on a distal region of the std promoter region. Together, our results demonstrate the major influence of Crp as a novel transcriptional factor on std promoter expression and later production of Std fimbriae in Salmonella.

中文翻译：

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鉴定 Crp 作为沙门氏菌 Std 菌毛表达的新型调节剂

沙门氏菌伤寒血清型基因组包含 14 个假定的菌毛系统。Std 菌毛属于chaperone-usher 家族，其调控尚未在伤寒沙门氏菌中进行研究。先前在密切相关的鼠伤寒血清型中发现了几种性病的调节剂。我们假设 S. Typhimurium 的调节剂可能与 S. Typhi 共享，但其他几种调节剂仍有待发现。在这里，我们描述了 50 多种不同候选调节剂对 std 表达的作用。研究了三种类型的调节剂：鼠伤寒沙门氏菌中的已知调节剂、计算机预测调节剂和毒力/代谢调节剂。在调节突变体中测定 std 的表达并与野生型菌株进行比较。总体而言，21 个调节器突变影响 std 启动子表达。Crp的作用，进一步研究了新确定的 std 表达因子。Crp 作为 std 启动子区域远端区域 std 表达的激活剂。总之，我们的结果证明了 Crp 作为一种新型转录因子对沙门氏菌中 std 启动子表达和随后的 Std 菌毛产生的主要影响。