Zhang, Y.Osei-Adjei, G.Ni, B.Fang, H.Zhang, L.Zhao, X.Sun, F.2022-09-082022-09-08201610.1016/j.micpath.2016.06.003.https://pubmed.ncbi.nlm.nih.gov/27289037/http://atuspace.atu.edu.gh:8080/handle/123456789/225Vibrio parahaemolyticus is a leading cause of seafood-associated diarrhea and gastroenteritis. This bacteria expresses a major virulence determinant called T3SS1. Expression of T3SS1 is tightly regulated by the ExsA-ExsC-ExsD regulatory system. The transcription of exsA and probably exsC is repressed directly by the H-NS protein. In this study, the regulation of exsD by H-NS was investigated using quantitative RT-PCR, primer extension, LacZ fusion, electrophoretic mobility shift, and DNase I footprinting assays. The results showed that His-H-NS protected a single region from 61 bp to 174 bp upstream of exsD against DNase I digestion, and a transcription start site located at 105 bp upstream of exsD was detected and its activity was repressed by H-NS. Therefore, a single H-NS-dependent promoter was transcribed for exsD in V. parahaemolyticus. Thus, all three genes in the ExsA-ExsC-ExsD regulatory system of T3SS1 are directly repressed by H-NS in V. parahaemolyticus.enH-NST3SS1Vibrio parahaemolyticusexsDArticle