DNA replication and late protein synthesis during SP82 infection of Bacillus subtilis

Bacteriophage SPO1 gene 27: location and nucleotide sequence

Bacteriophage SPO1 gene 27, whose product is required for late gene transcription and DNA replication, has been cloned in Escherichia coli, and its complete nucleotide sequence has been determined. We infer that the product of gene 27 is a highly basic 17,518-dalton protein of 155 amino acids. The gene for this regulatory protein is transcribed from two promoters: an early promoter situated before the adjacent upstream gene 28 and a middle promoter located between genes 28 and 27.

Transcriptional regulation of bacteriophage SPO1 protein synthesis in vivo and in vitro

There are six classes of SPO1 transcripts which are, at least partially, regulated independently of each other. Analysis of proteins made in infections by phage mutants defective in DNA synthesis, or in genes which positively control transcription, permitted each protein to be assigned to one transcription class. Most of the late proteins belong to transcription class m2l. There seem to be few, if any, phage proteins in the l class whose mRNA synthesis depends absolutely on phage DNA synthesis, UV irradiation of host cells allowed the detection of many additional early proteins. The early proteins detected in vivo were compared with proteins synthesized in vitro, using bacterial or gp28 phage-modified RNA polymerase in an Escherichia coli cell-free system. Proteins characterized in vivo as belonging to the e transcription class could be made efficiently in vitro only when transcription was performed by bacterial RNA polymerase. em proteins could be elicited through the use of either bacterial or gp28 polymerase, indicating that their genes can be transcribed in either the early or the middle mode.

Predominance of bacteriophage SP82 over bacteriophage SP01 in mixed infections of Bacillus subtilis

In mixed infections with Bacillus subtilis phages SP82 and SP01, the SP82 genotype is predominant among the progeny. This predominance is determined by a specific region of the genome, the pos region, which apparently is located near genes 29 to 32 (by the SP01 numbering system). Recombination between SP82 and SP01 yields phage which have both the SP82 pos region and an SP01 mutation. This mutation then behaves in mixed infection as if it were part of an SP82 genome.

DNA strand specificity of temporal RNA classes produced during infection of Bacillus subtilis by SP82

The DNA of the Bacillus subtilis bacteriophage SP82 has been separated into heavy (H) and light (L) fractions by centrifugation in buoyant density gradients in the presence of polyguanylic acid. Competition-hybridization experiments were performed with these separated fractions using RNAs isolated from cells labeled at intervals which account for 80% of the lytic cycle and unlabeled competitor RNAs isolated from phage-infected cells at 2-min intervals throughout infection. The analysis of temporal RNA classes were facilitated by use of a double reciprocal plot of the data. Five temporal classes binding to the H fraction and three binding to the L fraction were detected; the possible existence of an additional class transcribed from the H fraction is discussed. RNA synthesized in the presence of chloramphenicol contains two of the three classes produced from L-DNA and two of the five classes transcribed from H-DNA.

Bacteriophages of Bacillus subtilis

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