Analysis of nutR: A region of phage lambda required for antitermination of transcription

Abstract

The N gene product of coliphage lambda acts with host factors (Nus) through sites (nut) to render subsequent downstream transcription resistant to a variety of termination signals. These sites, nutR and nutL, are downstream, respectively, from the early promoters PR and PL. Thus a complicated set of molecular interactions are likely to occur at the nut sites. We have selected mutations in the nutR region that reduce the effectiveness of pN in altering transcription initiating at the PR promoter. DNA sequence analysis of three independently selected mutations revealed, in each case, a deletion of a single base pair in the cro gene. Consideration of the effect of such mutations on the extension of translation of cro message into the adjacent downstream nut region led to the identification of a consensus sequence CGCTCT(T)TAA that appears to play a role in the recognition of a host factor, possibly the NusA protein.

The α subunit of E. coli RNA polymerase activates RNA binding by NusA

“…There is evidence that NusA may interact directly with nucleotides in both the boxA and boxB components of the nut site (Olson et al 1982;Friedman and Olson 1983;Olson et al 1984;Mogridge et al 1995). The effects of mutations in the S1 homology region of NusA between amino acids 136 and 240 suggest that this region is important for antitermination.…”

“…Antitermination by N requires a cis-acting RNA element, called the nut site, which consists of two functional components, boxA and boxB (Salstrom and Szybalski 1978;de Crombrugge et al 1979;Olson et al 1982;Das and Wolska 1984;Horwitz et al 1987). NusA, as well as the E. coli proteins NusB, NusE (ribosomal protein S10), NusG, RNA polymerase, and the nut site on the phage RNA, take part in multiple interactions within the N-modified transcription complex (for review, see Friedman 1988;Greenblatt et al 1993).…”

‘boxA’‐like sequence between the 16 S/23 S spacer in rRNA operon of mycoplasmas

“…A nucleotide sequence similar to the '-10' box of prokaryotic promoters was identified at upstream sites of the boxA.like sequence in the 16 S/23 S spacer regions. These structures may represent an internal promoter between the 16 S and 23 S rRNA genes in mycoplasmas.boxA; rRNA; Antitermination; Mycoplasma; PromoterThe so-called boxA sequence, originally found at upstream regions of the nut site of the lambda phage genome, is considered to be the recognition site for the Escherichia coli host NusA protein, a transcription termination factor [1]. A sequence homologous to the boxA of phage lambda has also been identified in the tryptophanase operon [2], and in the leader sequence of glutamate synthase structural genes [3] of E. coll.…”

“…The so-called boxA sequence, originally found at upstream regions of the nut site of the lambda phage genome, is considered to be the recognition site for the Escherichia coli host NusA protein, a transcription termination factor [1]. A sequence homologous to the boxA of phage lambda has also been identified in the tryptophanase operon [2], and in the leader sequence of glutamate synthase structural genes [3] of E. coll.…”

The nut site of bacteriophage lambda is made of RNA and is bound by transcription antitermination factors on the surface of RNA polymerase.

“…The nutL and nutR sites of bacteriophage h have two genetically defined components: boxA and boxB. The k boxA sequence is traditionally defined as CGCTCTT (Olson et al 1982;Peltz et al 1985); however the 9 or 10 nucleotides immediately downstream of it (the extended boxA homology region) are evolutionarily conserved in lambdoid bacteriophages (Morgan 1986) and are known to be important for transcription antitermination by N (Zuber et al 1987). boxB is located 9 or 10 bp downstream from the core boxA sequence.…”