A dominant mutation in the bacteriophage lambda S gene causes premature lysis and an absolute defective plating phenotype.
The S and R genes of the bacteriophage lambda are required for lysis of the host. R encodes 'endolysin', a soluble transglycosylase which accumulates in the cytoplasm during late protein synthesis. S encodes a 'holin', a small membrane protein which, at a precisely scheduled time, terminates the vegetative cycle by forming a lethal lesion in the membrane through which gpR gains access to the peptidoglycan. A missense allele of S, Ala52Gly, causes lysis to occur prematurely at about 19-20 min after induction of a lysogen, compared to 45 min for the wild type. This allele has a severe plaque-forming defect which appears to be entirely a consequence of the early lysis and resultant severe reduction in particle burst size. The early-lysis phenotype is dominant and is aggravated, in terms of an even more reduced burst size, at both 30 degrees C and 42 degrees C. The mutation maps in the middle of a putative membrane-spanning helical domain of S, near the sites of other S- mutations with recessive non-lytic phenotypes. The mutation has no effect on S-protein accumulation or on the ratio of S107 and S105 products in the membrane. The mutation appears to affect the intrinsic timing function by which the S protein controls the lysis schedule.
Johnson-Boaz
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R
Department of Biochemistry and Biophysics, Texas A&M University, College Station 77843.
Chang
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CY
Young
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R
D000483:Alleles; D000595:Amino Acid Sequence; D001433:Bacteriolysis; D010582:Bacteriophage lambda / Q000235:genetics* / Q000502:physiology; D001483:Base Sequence; D010450:Endopeptidases / Q000502:physiology; D004926:Escherichia coli / Q000821:virology; D005799:Genes, Dominant; D005814:Genes, Viral; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D013696:Temperature; D010948:Viral Plaque Assay; D014764:Viral Proteins / Q000235:genetics* / Q000502:physiology; D015678:Viral Structural Proteins / Q000235:genetics*
D014764:Viral Proteins; D015678:Viral Structural Proteins; C082001:bacteriophage lambda lysis effector protein S105; C082002:bacteriophage lambda lysis inhibitor protein S107; D010450:Endopeptidases; C001143:endolysin