Affiliation:
1. Department of Biology, Texas A&M University, College Station 77843-2128, USA.
Abstract
The S gene of bacteriophage lambda encodes the holin required for release of the R endolysin at the onset of phage-induced host lysis. S is the promoter-proximal gene on the single lambda late transcript and spans 107 codons. S has a novel translational initiation region with dual start codons, resulting in the production of two protein products, S105 and S107. Although differing only by the Met-1-Lys-2... N-terminal extension present on S107, the two proteins are thought to have opposing functions, with the shorter polypeptide acting as the lysis effector and the longer one acting as an inhibitor. The expression of wild-type and mutant alleles of the holin gene has been assessed quantitatively with respect to the scheduling of lysis. S mRNA accumulates during the late gene expression period to a final level of about 170 molecules per cell and is maintained at that level for at least the last 15 min before lysis. Total S protein synthesis, partitioned at about 2:1 in favor of the S105 protein compared with the other product, S107, accumulates to a final level of approximately 4,600 molecules per cell. The kinetics of accumulation of S is consistent with a constant translational rate of less than one S protein per mRNA per minute. Mutant alleles with alterations in the translational initiation region were studied to determine how the translational initiation region of S achieves the proper partition of initiation events at the two S start codons and how the synthesis of S105 and S107 relates to lysis timing. The results are discussed in terms of a model for the pathway by which the 30S ribosome-fMet-tRNA complex binds to the translational initiation region of S. In addition, analysis of the relationship between lysis timing and the levels of the two S gene products suggests that S107 inhibits S105, the lethal lysis effector, by a stoichiometric titration.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Reference54 articles.
1. Adhya S. A. Sen and S. Mitra. 1971. The role of gene S p. 743-746. In A. D. Hershey (ed.) The bacteriophage lambda. Cold Spring Harbor Laboratory Cold Spring Harbor N.Y.
2. S gene product: identification and membrane localization of a Iysis control protein;Altman E.;J. Bacteriol.,1983
3. Subcellular localization of lethal Iysis proteins of bacteriophages lambda and ~X174;Altman E.;J. Virol.,1985
4. Ribosome gymnasticsdegree of difficulty 9.5, style 10.0;Atkins J. F.;Cell,1990
5. The R gene product of bacteriophage lambda is the murein transglycosylase;Bienkowska-Szewczyk K.;Mol. Gen. Genet.,1981
Cited by
101 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献