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M Russel

Publications and source records attributed to M Russel.

63 records · Page 4Linked to original sources
PubMed1981

A mutation downstream from the signal peptidase cleavage site affects cleavage but not membrane insertion of phage coat protein.

Morphogenesis of filamentous phage includes synthesis of the phage major coat protein in precursor form, its insertion into the host cell plasma membrane, its cleavage to the mature form of the protein, and its assembly there into virions. The M13 mutant am8H1R6 encodes a coat protein in which leucine replaces glutamic acid as residue 2 of the mature protein [Boeke, J. D., Russel, M. & Model, P. (1980) J. Mol. Biol. 144, 103-116]. The coat protein precursor produced by this variant is a poor substrate for the Escherichia coli signal peptidase both in vivo and in vitro. This pre-coat protein, which is eventually processed and assembled into viable phage particles, is associated with the membrane fraction of the infected cell. We conclude that the domain recognized by the signal peptidase extends beyond the signal peptide itself. Furthermore, membrane association and signal peptide cleavage can be separated temporally under conditions that permit membrane insertion, cleavage, and phage assembly.

Coliphages↗
PubMed1981

Filamentous phage assembly: membrane insertion of the major coat protein.

The assembly of filamentous bacteriophages has been studied in cells infected by wild-type and mutant phage; host mutants defective in bacteriophage assembly have also been isolated. Phage assembly takes place at the membrane, and requires insertion of the viral major coat protein. We present data on the physiology of this process and on the effects of amino acid sequence variations near to the coat protein amino terminus on membrane insertion, processing, and phage assembly.

Coliphages↗
PubMed1976

Regulation of gene 32 expression during bacteriophage T4 infection of Escherichia coli.

The gene 32 protein of the bacteriophage T4 plays an important role in genetic recombination, DNA repair, and DNA replication; the protein functions in these processes by virtue of a strong binding capacity for single-stranded DNA. During infections of Escherichia coli by bacteriophage carrying amber of temperature-sensitive mutations in gene 32, the altered gene 32 protein (that is, the amber fragment of the missense polypeptide) is synthesized at greatly elevated rates. During infections by phages that are mutant in other genes (and wild type in gene 32), gene 32 expression is coupled to the quantity of single-stranded DNA produced during the infection. The data are consistent with a model in which the gene 32 protein binds preferentially to all available single-stranded DNA. When all available single-stranded DNA is complexed with gene 32 protein, free gene 32 protein represses its own synthesis. The high level expression of altered gene 32 proteins (amber fragments or missense polypeptides) is a direct consequence of the proposed autoregulation.

Coliphages↗
PubMed1976

Translational, autogenous regulation of gene 32 expression during bacteriophage T4 infection.

Functional half-life measurements of the bacteriophage T4 gene 32 messenger RNA indicate that this mRNA is extremely stable. Regulation of gene 32 expression at the transcriptional level cannot account for the rapidity with which P32 synthesis can be repressed. Furthermore, derepression of P32 synthesis occurs in the presence of rifampicin, a drug which inhibits transcriptional initiation. In addition, T4-infected cultures in which P32 expression is repressed possess almost as much gene 32 mRNA as derepressed cultures. We conclude that expression of the T4 gene 32 protein is regulated at the level of translation.

Coliphages↗
PubMed1974

Some acridine-resistant mutations of bacteriophage T4D.

Three new 9-aminoacridine (9AA) resistant mutations of bacteriophage T4D have been isolated and characterized. Two of the mutations, rs and rc, have identical patterns of acridine resistance, but they map on opposite sides of the rII region. In addition, rs has an effect on the plaque morphology of r mutations, whereas rc does not. The third mutation, ama, maps very close to rs but exhibits a different pattern of resistance to 9AA. None of the three is resistant to acridines by virtue of reduced permeability. Taken together with other mutations that have been previously characterized, these new mutations permit us to set the minimum number of acridine-sensitive processes in T4 development at four.

Acridines↗