Localization and regulation of bacteriophage Mu promoters

Abstract

on Southern blots. Signals were detected from four new promoters in addition to the previously characterized Pe (early), PCM (repressor), and P,om (late) promoters. A major signal upstream of C was first observed at 12 min and intensified thereafter with RNA from cts and C amber but not replication-defective prophages; these characteristics indicate that this signal arises from a middle promoter, which we designate Pm. 40-min RNA, four additional major signals originated in the C-lys, F-G-I, N-P, and com-mom regions. These signals were missing with RNA from C amber and replication-defective prophages and therefore reflected the activity of late promoters, one of which we presume was Po,,, Uninduced lysogens showed weak signals from five regions, one from the early regulatory region, three between genes B and lys, and one near the late genes K, L, and M. The first of these probably resulted from PCM activity; the others remain to be identified.

Activation of the bacteriophage Mu lys promoter by Mu C protein requires the sigma 70 subunit of Escherichia coli RNA polymerase

“…Transcripts produced during lytic development fall into early, middle, and late classes, which are all transcribed rightward (1,19,26,33; C. F. Marrs, Ph.D. thesis, University of Wisconsin, Madison, 1982). At early times after the induction of a Mu prophage, transcription from P, results in the expression of replication functions (15,33).…”

“…In addition, Mu development requires the host core RNA polymerase (31). The absence of detectable leader transcripts and the C dependence of ,-galactosidase expression from late promoter-lacZ fusions containing only a few bases of the Mu RNA 5' end make it unlikely that C is an antiterminator (18,26). C binds to Pm.., DNA (20), and its footprint overlaps the late promoter consensus sequence in P,ys and Pmom (2) MATERIALS AND METHODS Media, chemicals, and enzymes.…”

“…The late region (the rightmost -27 kilobase pairs of the genome), which includes genes for phage morphogenesis and host range, cell lysis (lys), and DNA modification (mom), is transcribed from four major late promoters, Plys, PI, Pp, and Pmom (2,9,18,26,29). C is the only Mu protein required to initiate transcription in vivo from these promoters (10,11,17,18).…”

DNA Binding Specificity of Mu Transcription Factor C and Crystallization of C : DNA Complex

“…Following entero-bacterial infection, depending on the environment, nutrition and host cell conditions, Mu can form a lysogen or enter a lytic mode of replication for production of progeny phage particles. The lytic cycle is tightly regulated by a transcriptional cascade, which is divided into early, middle, and late phases (Figure 1-9) (Stoddard and Howe, 1989;Marrs and Howe, 1990). Transcription from the early promoter (P e ) is entirely independent of replication and de novo protein synthesis.…”

“…Early transcription starts from P e and does not require de novo protein synthesis or DNA replication. Middle transcription is dependent upon Mor, an activator protein expressed from the Mu early transcript (Stoddard and Howe, 1989;Mathee and Howe, 1990;Marrs and Howe, 1990). The middle transcript codes for the C protein, the activator of the four late promoters P lys , P I , P P , and P mom .…”