Form-determining function of the genes required for the assembly of the head of bacteriophage T4

Laemmli, Ulrich Karl; Mölbert, Elisabeth; Showe, Michael K.; Kellenberger, E.

doi:10.1016/0022-2836(70)90379-7

Cited by 251 publications

(157 citation statements)

References 12 publications

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“…Fractions (1 ml) were collected, concentrated using centrifugal filters (Millipore), and filter sterilized (0.2 m) prior to being tested in the 3-day infection assay. All fractions were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, using 12% polyacrylamide gels according to the method of Laemmli et al (18). The gels were either silver stained or transferred to nitrocellulose and analyzed by Western blotting, using polyclonal immunoglobulin G (IgG) anti-human lactoferrin antibody (1:250 in PBS containing 1% bovine serum albumin; Dako, Denmark) and polyclonal IgG human anti-SLPI antibody FIG.…”

Section: Methodsmentioning

confidence: 99%

Comparison of Human Immunodeficiency Virus Type 1-Specific Inhibitory Activities in Saliva and Other Human Mucosal Fluids

Kazmi

Naglik

Sweet

et al. 2006

Clin Vaccine Immunol

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Several human mucosal fluids are known to possess an innate ability to inhibit human immunodeficiency virus type 1 (HIV-1) infection and replication in vitro. This study compared the HIV-1 inhibitory activities of several mucosal fluids, whole, submandibular/sublingual (sm/sl), and parotid saliva, breast milk, colostrum, seminal plasma, and cervicovaginal secretions, from HIV-1-seronegative donors by using a 3-day microtiter infection assay. A wide range of HIV-1 inhibitory activity was exhibited in all mucosal fluids tested, with some donors exhibiting high levels of activity while others showed significantly lower levels. Colostrum, whole milk, and whole saliva possessed the highest levels of anti-HIV-1 activity, seminal fluid, cervicovaginal secretions, and sm/sl exhibited moderate levels, and parotid saliva consistently demonstrated the lowest levels of HIV-1 inhibition. Fast protein liquid chromatography gel filtration studies revealed the presence of at least three distinct peaks of inhibitory activity against HIV-1 in saliva and breast milk. Incubation of unfractionated and fractionated whole saliva with antibodies raised against human lactoferrin (hLf), secretory leukocyte protease inhibitor (SLPI), and, to a lesser extent, MG2 (high-molecular-weight mucinous glycoprotein) reduced the HIV-1 inhibitory activity significantly. The results suggest that hLf and SLPI are two key components responsible for HIV-1 inhibitory activity in different mucosal secretions. The variation in HIV inhibitory activity between the fluids and between individuals suggests that there may be major differences in susceptibility to HIV infection depending both on the individual and on the mucosal fluid involved.

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Section: Methodsmentioning

confidence: 99%

Comparison of Human Immunodeficiency Virus Type 1-Specific Inhibitory Activities in Saliva and Other Human Mucosal Fluids

Kazmi

Naglik

Sweet

et al. 2006

Clin Vaccine Immunol

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“…The ptg phenotype is probably also based on an alteration in vertex stabilization. Amber and temperature-sensitive mutations in gene 24 have been described as giving rise to 7 particles [since shown to be nearly normal preheads (26)] and polyheads (29). Temperature-sensitive mutants in gene 24, grown at intermediate temperatures, produce small numbers of infectious giant phage (36).…”

Section: Fig 2 Preheads and Polyheads Frommentioning

confidence: 99%

“…24 (amN65) lysates. Microscopy was carried out as described previously (15) (29,31). The production of polyheads instead of preheads by 22-mutants suggests that P22 acts with P20 and P40 in prehead initiation.…”

mentioning

confidence: 99%

Kinetic factors and form determination of the head of bacteriophage T4.

Showe¹,

Onorato²

1978

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

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The form of the bacteriophage T4 prehead is described by its icosahedral symmetry, its diameter, and its length. We show how each oftheseparameters is regulated during prehead formation and ascribe specific form-determining functions to the prehead proteins. The major protein of the head shell can assemble in several different forms. The structure produced in vivo depends on the rate of synthesis of the major protein relative to the rates of synthesis of minor shell proteins and the major core protein. From our observations, we propose a model for form determination of the prehead and suggest a pathway for the evolution of its prolate shape.The head of bacteriophage T4 has been extensively studied as a model for discovering mechanisms of form determination of biological structures. It is a prolate icosahedron of triangulation number (T) = 13 (1, 2) elongated on its 5-fold axis of symmetry (3), with a length-to-width ratio of 1.37 (4). It is assembled on the Escherichia colh inner membrane as a core-containing prehead (5), which is matured to the finished head by a series of reactions that includes limited proteolysis of capsid and core proteins, expansion of the prehead shell lattice, and packaging of the phage DNA (6). The relatively large size and the prolate shape of the T4 head suggest that the prehead [in which the form is already determined (4)] cannot be produced by simple self-assembly of the shell protein, as is possible with small regular icosahedral viruses (7,8).A number of mechanisms have been proposed (9, 10) to account for form determination in the assembly of large or anisometric virus shells or other structures in which simple selfassembly of identical subunits is not possible (11). They include regulation by a genetically defined "measuring rod" or template, a vernier, and accumulating strain with the addition of subunits. Of these, only the "measuring rod" model, (the determination of the length of tobacco mosaic virus by its RNA) has been experimentally demonstrated (12,13). All of these models depend strongly on specific interactions between the polymerizing subunits, but Wagenknecht and Bloomfield (14) have shown theoretically how the length of linear aggregates might also depend on the concentration of the polymerizing subunits.Recent observations on the role of minor proteins in prehead formation, and on changes in prehead length that depend on subunit concentrations, suggest that kinetic factors as well as specific protein-protein interactions regulate the form of the T4 prehead.The form of the T4 prehead is described by its symmetry (icosahedral), its width, and its length (extension along the 5-fold axis of symmetry). We account for these in the following way. The symmetry is determined by formation of a 5-fold symmetric initiation complex that directs assembly of the shell into closed structures instead of open tubes. The width is determined by the intrinsic curvature of the shell and the diameter of the core that it must enclose. The length can be varied. It is regulated by t...

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“…T h s was initially suggested by the discovery of Epstein et al (1) that the formation of the head of phage T4 required the products of more than ten phage genes, and by the complex nature of the defective structures that accumulated in cells infected with mutants in these genes as shown by Kellenberger and Laemmli (2,3). In addition we now know that the formation of bacteriophage heads is coupled with the maturation of the virus chromosome; cutting of a mature length chromosome from the overlength replicating DNA does not happen in solution but only in the presence of a head precursor shell (4)(5)(6)(7)(8).…”

Section: Introductionmentioning

confidence: 99%

P22 morphogenesis I: Catalytic scaffolding protein in capsid assembly

1974

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About 250 molecules of the 42,000 molecular weight gene 8 product catalyze the polymerization of the major phage coat protein into a precursor shell temporarily containing both proteins. The resulting prohead appears to be a shell structure with the P8, or scaffolding protein, on the inside, and the coat protein on the outside. In concert with DNA condensation inside the shell, all 250 scaffolding molecules exit from the prohead, without proteolytic cleavage. These molecules then recycle and catalyze the formation of more proheads from newly synthesized coat protein. Such proteins, which catalyze assembly by temporarily associating with an intermediate stage, may represent a general mechanism of macromolecular assembly.

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Form-determining function of the genes required for the assembly of the head of bacteriophage T4

Cited by 251 publications

References 12 publications

Comparison of Human Immunodeficiency Virus Type 1-Specific Inhibitory Activities in Saliva and Other Human Mucosal Fluids

Comparison of Human Immunodeficiency Virus Type 1-Specific Inhibitory Activities in Saliva and Other Human Mucosal Fluids

Kinetic factors and form determination of the head of bacteriophage T4.

P22 morphogenesis I: Catalytic scaffolding protein in capsid assembly

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