Journal of Microbiology

Journal Article

Characterization of transcriptional activities at a divergent promoter of the type VI secretion system in enterohemorrhagic Escherichia coli O157:H7: Se Kye Kim , Jun Bong Lee , Jang Won Yoon; J. Microbiol. 2022;60(9):928-934. Published online August 19, 2022; DOI: https://doi.org/10.1007/s12275-022-2109-9

Abstract: The type VI secretion system (T6SS) is a novel secretion system found in many Gram-negative bacteria that plays a role in bacterial competition, virulence, and host immune evasion. The enterohemorrhagic Escherichia coli (EHEC) O157:H7 strain EDL933 has a single functional T6SS gene cluster. In this study, we attempted to characterize the transcriptional pattern of the T6SS effector gene Z0264 in EDL933. Transcriptional analyses showed that Z0264 and other T6SS genes were transcribed in vitro in a growth-phase-dependent manner, but Z0264 was not secreted in the rich medium. Using adapter- and radioactivity-free transcription start site analysis, we identified an overlapping divergent promoter between Z0264 and Z0265. A β-galactosidase assay with truncated promoter regions showed that the divergent promoter is functional. In addition, we demonstrated the role of H-NS as a repressor in the transcription of Z0264. Notably, the cDNA PCR assay showed that the mRNA transcript from the Z0264 promoter did not include the entire main T6SS cluster, suggesting segmented gene expression by multiple promoters in the T6SS cluster. In conclusion, we identified a divergent promoter for Z0264 located in the T6SS cluster of EDL933 and characterized its in vitro transcriptional activity during growth. Our findings provide insights and a preliminary understanding of the regulatory mechanisms underlying T6SS transcription.

Published Erratum

Erratum: Development of a Novel Korean H9-Specific rRT-PCR Assay and Its Application for Avian Influenza Virus Surveillance in Korea: Mingeun Sagong, Yong-Myung Kang, Na Yeong Kim, Eun Bi Noh, Gyeong-Beom Heo, Se-Hee An, Youn-Jeong Lee, Young Ki Choi, Kwang-Nyeong Lee; J. Microbiol. 2024;62(6):489-489.; DOI: https://doi.org/10.1007/s12275-024-00149-6

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