Structural Defects Of T-Even Bacteriophages

Cummings, Donald J.; Couse, N.L.; Forrest, Gerald L.

doi:10.1016/s0065-3527(08)60020-2

Cited by 19 publications

(5 citation statements)

References 68 publications

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“…Considering the smaller (or larger) than normal T4 heads as such mistakes in assembly can contribute to our understanding of T4 head assembly. The subunits of the T4 head are presently thought to be arranged in a prolate quasi-icosahedral structure (5,29,42) or in a twisted bipyramidal hexagonal prism (6,13). The two classes of heads which are intermediate in size between the isometric and the normal head can be explained within the framework of icosahedral or of hexagonal models, if we assume that the mid-portions of different heads differ in numbers of subunits.…”

Section: Discussionmentioning

confidence: 99%

Coordinate Variation in Lengths of Deoxyribonucleic Acid Molecules and Head Lengths in Morphological Variants of Bacteriophage T4

Mosig

Carnighan

Bibring

et al. 1972

J Virol

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We have investigated three classes of small bacteriophage T4 particles which differ from normal T4 particles in length of their deoxyribonucleic acid (DNA), in head length, in protein content, and in density. The different particles contain DNA molecules measuring 0.90, 0.77, or 0.67, respectively, of the normal T4 length. An additional class of viable particles contains DNA molecules of 1.1 unit length. These discrete differences in DNA length correspond to discrete differences in length (but not width) of the respective heads and are roughly proportional to the resulting differences in head volumes. The measured relative dimensions of the different heads fit best the relative dimensions predicted by a quasi-icosahedral model in which the smallest T4 head corresponds to an icosahedron with a triangulation number T = 21. The mid-portion of this structure is thought to be elongated by adding successive rows of gene 23 protein hexamers, the normal T4 head having three added rows. Different mutants produce small particles of the three classes in varying proportions, but no mutant produces exclusively particles of a single class. Particles of each class, with indistinguishable DNA content, show additional minor differences in protein content, as measured by differences in buoyant density and in the relative ratio of 32p to 35S.

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Section: Discussionmentioning

confidence: 99%

Coordinate Variation in Lengths of Deoxyribonucleic Acid Molecules and Head Lengths in Morphological Variants of Bacteriophage T4

Mosig

Carnighan

Bibring

et al. 1972

J Virol

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“…Techniques for zone sedimentation through 10-30% (w/v) sucrose (BUM) gradients, as well as density gradient centrifugation in CsCl (adjusted to 1.32 g/cm3), have been described (9,13). For counting of radioactivity, 20 Al of a 15-drop fraction was put on a Whatman GF/C glass-fiber filter or 15-drop fractions were collected directly into test tubes containing 2.5 ml of cold 5% trichloroacetic acid. In the latter case, the acid-insoluble material was collected on Millipore filters.…”

Section: Methodsmentioning

confidence: 99%

Bacteriophage T4 Head Morphogenesis. Isolation, Partial Characterization, and Fate of Gene 21-Defective Tau-Particles

Luftig

Lundh

1973

Proc. Natl. Acad. Sci. U.S.A.

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A lysozyme-detergent procedure was developed for isolation of tau-particles from cells infected by gene-21 mutants of T4 bacteriophage. These particles have a sedimentation coefficient of 440 h 10 S. They contain less than 1% detectable nuclease-resistant DNA, are smaller (650 X 850 A) than normal bacteriophage heads (800 X 1100 A), and exhibit two major bands on 7.5% Na dodecyl sulfate-acrylamide gels. The more prominent band (55,000 daltons) corresponds to the uncleaved, major capsid polypeptide (P23); the other band (32,000 daltons) corresponds to the gene-22 product (P22). Temperatureshift experiments with cells infected with tsN8 (gene 21) mutants were used to study the fate of tau-particles accumulated under nonpermissive conditions. 50 Min after ts N8-infected cells were shifted from the nonpermissive (41.50) to the permissive (250) temperature, a phage burst occurred that was 75% of that observed with wild-type phage. However, in "pulse-chase" temperature-shift experiments, the radioactive tau-particle peak only slightly decreased (by 10-14%) by 50 min after the shift, whereas an increased amount of radioactivity (about four times as much as the tau-particle decrease) appeared in phage particles. The results suggest that at least two pools of head polypeptides coexist in cells infected with gene-21 mutants. One pool is composed of head subunits assembled into tau-particles, which are mostly aberrant structures; the second pool is composed of head subunits that are incorporated into mature phage when the gene-21 product becomes functional.

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“…The significance of the closed polyheads (as well as rare monster phage particles) will be made clear in a later section. The only other compound that specifically gave rise to polyheads was dimethyl sulfoxide (25,33). This compound is particularly interesting since it had previously been shown that treatment of phage particles with dimethyl sulfoxide results in the separation of heads from tails (30).…”

Section: T4 Head-related Aberrant Substructuresmentioning

confidence: 99%

Head length control in T4 bacteriophage morphogenesis: effect of canavanine on assembly.

Cummings¹,

Bolin²

1976

Bacteriological Reviews

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Structural Defects Of T-Even Bacteriophages

Cited by 19 publications

References 68 publications

Coordinate Variation in Lengths of Deoxyribonucleic Acid Molecules and Head Lengths in Morphological Variants of Bacteriophage T4

Coordinate Variation in Lengths of Deoxyribonucleic Acid Molecules and Head Lengths in Morphological Variants of Bacteriophage T4

Bacteriophage T4 Head Morphogenesis. Isolation, Partial Characterization, and Fate of Gene 21-Defective Tau-Particles

Head length control in T4 bacteriophage morphogenesis: effect of canavanine on assembly.

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