https://phaidra.vetmeduni.ac.at/o:1712 Impact of a Novel PagR-like Transcriptional Regulator on Cereulide Toxin Synthesis in Emetic Bacillus cereus Kalbhenn, Eva Maria Eva Maria Kalbhenn University of Veterinary Medicine Vienna Ehling-Schulz, Monika Monika Ehling-Schulz 0000-0001-7384-0594 University of Veterinary Medicine Vienna Frenzel, Elrike Elrike Frenzel University of Veterinary Medicine Vienna Stark, Timo D. Timo D. Stark 0000-0002-6502-173X Technical University of Munich Grass, Gregor Gregor Grass 0000-0002-8002-7718 Bundeswehr Institute of Microbiology Kranzler, Markus Markus Kranzler 0000-0001-9273-8341 University of Veterinary Medicine Vienna Gacek-Matthews, Agnieszka Agnieszka Gacek-Matthews 0000-0001-5884-583X University of Veterinary Medicine Vienna MDPI text eng The emetic type of foodborne disease caused by Bacillus cereus is produced by the small peptide toxin cereulide. The genetic locus encoding the Ces nonribosomal peptide synthetase (CesNRPS) multienzyme machinery is located on a 270 kb megaplasmid, designated pCER270, which shares its backbone with the Bacillus anthracis toxin plasmid pXO1. Although the ces genes are plasmid-borne, the chromosomally encoded pleiotropic transcriptional factors CodY and AbrB are key players in the control of ces transcription. Since these proteins only repress cereulide synthesis during earlier growth phases, other factors must be involved in the strict control of ces expression and its embedment in the bacterial life cycle. In silico genome analysis revealed that pCER270 carries a putative ArsR/SmtB family transcription factor showing high homology to PagR from B. anthracis. As PagR plays a crucial role in the regulation of the protective antigen gene pagA, which forms part of anthrax toxin, we used a gene-inactivation approach, combined with electrophoretic mobility shift assays and a bacterial two-hybrid system for dissecting the role of the PagR homologue PagRBc in the regulation of cereulide synthesis. Our results highlight that the plasmid-encoded transcriptional regulator PagRBc plays an important role in the complex and multilayered process of cereulide synthesis. Escherichia-Coli; Identification; Virulence; Protein; Expression; Anthracis; Family; Repressors; Plasmids; System http://creativecommons.org/licenses/by/4.0/ https://phaidra.vetmeduni.ac.at/api/object/o:1712/download 10.3390/ijms231911479 https://phaidra.vetmeduni.ac.at/o:605 application/pdf International Journal of Molecular Sciences 23(19) (2022) International Journal of Molecular Sciences 23 19 942.53 kB 2022