Mechanism of head assembly and DNA encapsulation in Salmonella phage P22

King, Jonathan; Lenk, Elaine V.; Botstein, David

doi:10.1016/0022-2836(73)90205-2

Cited by 218 publications

(184 citation statements)

References 38 publications

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“…P22 procapsids made during a typical infection contain about 250 -300 molecules of scaffolding protein (2,14,25,30,31), but there can be as few as 60 depending on assembly conditions (31)(32)(33)(34). Without scaffolding protein, coat protein polymerizes in vivo and in vitro into aberrant forms such as empty, closed T ϭ 7 or T ϭ 4 shells and spiral type "monster" structures (35)(36)(37)(38). Scaffolding protein is also required for incorporation of the portal protein ring (32,39,40) and at least one of the three minor proteins that are essential for subsequent DNA ejection during infection (39 -41).…”

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confidence: 99%

Unraveling the Role of the C-terminal Helix Turn Helix of the Coat-binding Domain of Bacteriophage P22 Scaffolding Protein

Padilla-Meier

Gilcrease

Weigele

et al. 2012

Journal of Biological Chemistry

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Background: Viral scaffolding proteins interact with coat proteins to drive procapsid assembly. Results: Amino acid substitutions in the turn and between the helices of the coat protein-binding domain of scaffolding protein block procapsid assembly. Conclusion:The orientation of helices in the scaffolding helix turn helix domain is critical for procapsid assembly. Significance: Understanding scaffolding/coat protein interactions illuminates the mechanism of assembly of many large viruses.

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confidence: 99%

Unraveling the Role of the C-terminal Helix Turn Helix of the Coat-binding Domain of Bacteriophage P22 Scaffolding Protein

Padilla-Meier

Gilcrease

Weigele

et al. 2012

Journal of Biological Chemistry

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“…Genetic analysis of amber and temperature sensitive mutants by Botstein and coworkers (22) has revealed ten viral genes whose products are necessary for the formation of a complete virus particle (23). The pathway for the assembly of these proteins into a phage particle is reasonably well understood (24); however, before reviewing the assembly pathway we will briefly describe the methods employed for those who are not familiar with bacteriophage experiments.…”

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confidence: 99%

“…Figure 2 summarizes the pathway for the assembly of phage P22. Three kinds of structures can be isolated from wild-type cells: proheads, empty heads, and phage (23,24) (see also Fig. 1).…”

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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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“…The gene 9 protein is present in unfinished head-like structures ("proheads") but not in DNA-containing heads (25). It may thus act as a scaffold around which the head is assembled (26). Mutants defective in genes 18 and 19 fail to mature their DNA, and yet the products of these genes do not appear to be structural components of the head (25).…”

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confidence: 99%

Packaging and Maturation of DNA of Bacteriophage T7 In Vitro

Kerr¹,

Sadowski²

1974

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

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We have developed an in vitro complementation assay to demonstrate packaging and maturation of DNA of phageT7. Cells of Escherichia coli B infected with an appropriate T7 amber mutant are concentrated 200-fold and iysed by freezing and thawing. Two extracts from cells infected with different amber mutants are mixed and incubated at 300. Positive complementation results in a 100-fold increase in phage titer.Using this assay we have demonstrated the packaging of phage DNA from an extract that contains no phage heads (gene 9-, 10-), within head structures present in an extract that contains no phage DNA (gene 5-). We have also demonstrated an activity in extracts that contain no phage DNA or heads (gene 5-,9, 10-), which complements gene 19-infected cells. We have proven that this activity is due to the gene-19 product by showing that the activity is temperature-sensitive if the extract is made from cells infected with a mutant having a temperature-sensitive mutation in gene 19. This assay should be useful in elucidating the mechanism of packaging and maturation of DNA of phage T7.In recent years there has been rapid progress in our understanding of the mechanisms by which complex bacteriophages are assembled. Thus, for bacteriophage T4, we know a great deal about the pathways of assembly of tail fibers (1-4), baseplates, sheaths, and cores of the tail (5-9) and assembly of the head (10). These advances have been aided greatly by the development by Edgar and Wood of methods for performing these reactions in cell-free extracts (11,12).The DNA of several bacteriophages (T4, T7, X, and P22) has been shown to replicate as molecules that are several times longer than the DNA found inside the head of the mature virus (13)(14)(15)(16)(17). It is also known that maturation of these long chains of DNA to monomeric units is closely coupled to the formation of the phage head, since cells infected with mutants that are defective in head formation accumulate these long molecules of immature DNA (18-21).However, our knowledge of the molecular mechanisms whereby the immature phage DNA enters the head ("DNA packaging") and is cleaved to monomeric length ("DNA maturation") has been limited, in part, by the inability to perform these reactions in vitro. Recently, however, assays have been developed to demonstrate packaging of phage DNA in vitro. Kaiser and Masuda (22) showed that exogenous lambda DNA could be packaged by extracts from induced lysogens and Hohn and Hohn (23) have demonstrated that head-related particles containing no DNA ("petit lambda") can be filled with DNA in vitro. Finally, the experiments of Pruss, Goldstein, and Calendar (24) showed that the size of the head of phage P2 is determined solely by the proteins involved and not by the phage DNA.Bacteriophage T7 may be a convenient system in which to study DNA packaging and maturation because it is a 3545 relatively simple virus for which there is a great deal of information about its genetics and physiology (25). The DNA of phage T7 is a unique, terminall...

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Mechanism of head assembly and DNA encapsulation in Salmonella phage P22

Cited by 218 publications

References 38 publications

Unraveling the Role of the C-terminal Helix Turn Helix of the Coat-binding Domain of Bacteriophage P22 Scaffolding Protein

Unraveling the Role of the C-terminal Helix Turn Helix of the Coat-binding Domain of Bacteriophage P22 Scaffolding Protein

P22 morphogenesis I: Catalytic scaffolding protein in capsid assembly

Packaging and Maturation of DNA of Bacteriophage T7 In Vitro

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