The phage Mu ‘late’ gene transcription activator, C, is a site-specific DNA binding protein
Year: 1988
Type: article
Abstract: The bacteriophage Mu mom gene encodes a novel DNA modification that protects the viral genome against a wide variety of restriction endonucleases. Expression of mom is subject to a series of unusual regulatory controls. Transcription requires the action of a phage-encoded protein, C, which binds (probably as a dimer) the mom promoter from –33 to –52 (with respect to the transcription start site) in two adjacent DNA major grooves on one face of the helix. No apparent direct interaction between C and the host RNA polymerase (RNAP) is evident; however, C binding alters mom DNA conformation. In the absence of C, RNAP binds the mom promoter at a site that results in transcription in a direction away from the mom gene. The function of this transcription is unknown. An additional layer of transcriptional regulation complexity is due to the fact that the host Dam DNA-(N6-adenine)methyltransferase is required. Dam methylation of three closely spaced upstream GATC sequences is necessary to prevent binding by the host protein, OxyR, which acts as a repressor. Repression is not mediated by inhibition of C binding, but rather through interference with C-mediated recruitment of RNAP to the correct site. Translation of mom is regulated by the phage Com protein. Com is only 62 amino acids long and contains a zinc finger-like structure (coordinated by four cysteine residues) in the amino terminal domain. Com binds mom mRNA 5′ to the mom open reading frame, whose translation start signals are contained in a stem-loop translation-inhibition-structure. Com binding to its target site (5′ to and adjacent to the translation-inhibition-structure) results in a stable change in RNA secondary structure that exposes the translation start signals.
Source: Biochemical Pharmacology
Institution: University of Rochester
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,590
OpenAlex ID: W2012440360