title: The lysis cassette of DLP12 defective prophage is regulated by RpoE.
abstract: Expression of the lysis cassette (essD, ybcT, rzpD/rzoD) from the defective lambdoid prophage at the 12th minute of Escherichia coli's genome (DLP12) is required in some strains for proper curli expression and biofilm formation. Regulating production of the lytic enzymes encoded by these genes is critical for maintaining cell wall integrity. In lambdoid phages, late-gene regulation is mediated by the vegetative sigma factor RpoD and the lambda antiterminator Qλ. We previously demonstrated that DLP12 contains a Q-like protein (QDLP12) that positively regulates transcription of the lysis cassette, but the sigma factor responsible for this transcription initiation remained to be elucidated. In silico analysis of essDp revealed the presence of a putative - 35 and - 10 sigma site recognized by the extracytoplasmic stress response sigma factor, RpoE. In this work, we report that RpoE overexpression promoted transcription from essDp in vivo, and in vitro using purified RNAP. We demonstrate that the - 35 region is important for RpoE binding in vitro and that this region is also important for QDLP12-mediated transcription of essDp in vivo. A bacterial two-hybrid assay indicated that QDLP12 and RpoE physically interact in vivo, consistent with what is seen for Qλ and RpoD. We propose that RpoE regulates transcription of the DLP12 lysis genes through interaction with QDLP12 and that proper expression is dependent on an intact - 35 sigma region in essDp. This work provides evidence that the unique Q-dependent regulatory mechanism of lambdoid phages has been co-opted by E. coli harbouring defective DLP12 and has been integrated into the tightly controlled RpoE regulon.
authors.affiliation: Department of Microbiology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Karl-Gustav
authors.initials: KG
authors.lastname: Rueggeberg
authors.affiliation: Department of Microbiology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Faustino A
authors.initials: FA
authors.lastname: Toba
authors.affiliation: Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Jeremy G
authors.initials: JG
authors.lastname: Bird
authors.affiliation: Department of Microbiology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Nathan
authors.initials: N
authors.lastname: Franck
authors.affiliation: Department of Microbiology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Mitchell G
authors.initials: MG
authors.lastname: Thompson
authors.affiliation: Graduate Program in Environmental Toxicology, Cornell University, Ithaca, NY 14853, USA.|Department of Microbiology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Hay
mesh_terms: D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000821:virology*; D015964:Gene Expression Regulation, Bacterial; D015967:Gene Expression Regulation, Viral; D054884:Host-Pathogen Interactions; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D039002:Prophages / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D012808:Sigma Factor; D014764:Viral Proteins; C063202:sporulation-specific sigma factors