A mutation which bypasses the requirement for p24 in bacteriophage T4 capsid morphogenesis

McNicol, L A; Simon, Lee D.; Black, Lindsay W.

doi:10.1016/0022-2836(77)90216-9

Cited by 36 publications

(25 citation statements)

References 29 publications

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“…Therefore, the structures of these proteins should be similar with both proteins containing a HK97-like domain and an insertion domain. This conclusion is supported by the observation that point mutations in gene 23 allow gp23 to substitute for gp24 (6). A precedent for the major capsid protein and the vertex protein having a similar fold occurs in the lipid-containing icosahedral phage PRD1, in which both molecules are composed of two consecutive jellyrolls (25).…”

Section: Resultssupporting

confidence: 67%

“…The consensus cleavage site in gp24, inferred from experimentally determined sites in other T4 capsid proteins, is after Glu-10 (3). This position corresponds to an only partially exposed site close to the end of the first helix, consistent with only some of the gp24 molecules in the mature T4 capsid having been cleaved (6,18). A striking feature of the HK97 capsid protein is that during maturation the E loop becomes covalently crosslinked to a hairpin loop in a neighboring subunit.…”

Section: Resultsmentioning

confidence: 81%

“…A number of mutations in different genes coding capsid proteins lead to various abnormalities in assembly ranging from formation of isometric and͞or giant capsids to substitution of all gp24 pentamers with gp23 pentamers at the vertices (3,6). The latter observation suggests that the structures of gp23 and gp24, as well as the character of interactions between them, are probably similar.…”

mentioning

confidence: 68%

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Structural and functional similarities between the capsid proteins of bacteriophages T4 and HK97 point to a common ancestry

Fokine

Leiman

Shneider

et al. 2005

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

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Gene product (gp) 24 of bacteriophage T4 forms the pentameric vertices of the capsid. Using x-ray crystallography, we found the principal domain of gp24 to have a polypeptide fold similar to that of the HK97 phage capsid protein plus an additional insertion domain. Fitting gp24 monomers into a cryo-EM density map of the mature T4 capsid suggests that the insertion domain interacts with a neighboring subunit, effecting a stabilization analogous to the covalent crosslinking in the HK97 capsid. Sequence alignment and genetic data show that the folds of gp24 and the hexamer-forming capsid protein, gp23*, are similar. Accordingly, models of gp24* pentamers, gp23* hexamers, and the whole capsid were built, based on a cryo-EM image reconstruction of the capsid. Mutations in gene 23 that affect capsid shape map to the capsomer's periphery, whereas mutations that allow gp23 to substitute for gp24 at the vertices modify the interactions between monomers within capsomers. Structural data show that capsid proteins of most tailed phages, and some eukaryotic viruses, may have evolved from a common ancestor.evolution ͉ gene product 24 ͉ major capsid protein T he protein shells of viral capsids are remarkably stable, yet dynamic structures. They have to protect the genome during its transfer between hosts, withstand the high pressure of the condensed nucleic acid, and be able to release the genome once a susceptible host has been recognized. To reconcile both stability and dynamic requirements, assembled procapsids of many viruses undergo large conformational changes during genome packaging and maturation (1).The capsid of the dsDNA tailed bacteriophage T4 is a prolate icosahedron ( Fig. 1) whose capsomers form a T end ϭ 13 laevo hexagonal lattice in the end caps and a T mid ϭ 20 lattice in the cylindrical midsection (2). The protein shell consists of the major capsid protein gene product (gp) 23*, the pentameric vertex protein gp24*, the portal protein or ''connector'' gp20, and the two accessory proteins, gp hoc (highly antigenic outer capsid protein) and gp soc (small outer capsid protein) (3), that decorate the outside of the shell. The dodecameric connector replaces a pentamer of gp24* at one of the 12 vertices and serves as a special portal for DNA packaging, tail attachment, and DNA exit (4, 5).During procapsid assembly, gp23, gp24, and gp20 form a shell around the core structure composed primarily of the scaffolding protein gp22 and assembly protease gp21 (3). The protease activates once procapsid assembly has been completed and cleaves the proteins of the core into small peptides, most of which leave the maturing procapsid, freeing space for the genome. The gp21 protease also cleaves a 65-residue-long, amino-terminal fragment from the 56-kDa gp23, generating the 48.7-kDa gp23* (3). In addition, the 10-residue, amino-terminal region of the 48.7-kDa gp24 is cleaved, giving rise to the 47.6-kDa gp24* (3). These cleavages trigger a large conformational rearrangement in the procapsid, resulting in expansion and causing the ...

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Section: Resultssupporting

confidence: 67%

Section: Resultsmentioning

confidence: 81%

mentioning

confidence: 68%

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Structural and functional similarities between the capsid proteins of bacteriophages T4 and HK97 point to a common ancestry

Fokine

Leiman

Shneider

et al. 2005

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

Self Cite

200

207

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“…Gene 24 is believed to have arisen from an ancient duplication of gene 23. The interactions between gp23 and gp24 (9,21) are now thought to have only a minor role in the determination of virion shape and size (14). Some of the phylogenetically variable patches in gp23, however, could slightly modify the interactions between the gene 23 subunits in the virion, and this could result in differences in virion head size and shape.…”

Section: Resultsmentioning

confidence: 99%

Phylogeny of the Major Head and Tail Genes of the Wide-Ranging T4-Type Bacteriophages

et al. 2001

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We examined a number of bacteriophages with T4-type morphology that propagate in different genera of enterobacteria, Aeromonas, Burkholderia, and Vibrio. Most of these phages had a prolate icosahedral head, a contractile tail, and a genome size that was similar to that of T4. A few of them had more elongated heads and larger genomes. All these phages are phylogenetically related, since they each had sequences homologous to the capsid gene (gene 23), tail sheath gene (gene 18), and tail tube gene (gene 19) of T4. On the basis of the sequence comparison of their virion genes, the T4-type phages can be classified into three subgroups with increasing divergence from T4: the T-evens, pseudoT-evens, and schizoT-evens. In general, the phages that infect closely related host species have virion genes that are phylogenetically closer to each other than those of phages that infect distantly related hosts. However, some of the phages appear to be chimeras, indicating that, at least occasionally, some genetic shuffling has occurred between the different T4-type subgroups. The compilation of a number of gene 23 sequences reveals a pattern of conserved motifs separated by sequences that differ in the T4-type subgroups. Such variable patches in the gene 23 sequences may determine the size of the virion head and consequently the viral genome length. This sequence analysis provides molecular evidence that phages related to T4 are widespread in the biosphere and diverged from a common ancestor in acquiring the ability to infect different host bacteria and to occupy new ecological niches.

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“…A labeled gp16-containing bacterial lysate was harvested 50 min after the addition of the isotope at 37°C. Labeled bacterial extracts were prepared immediately after centrifugation by boiling in SDS-polyacrylamide gel electrophoresis running buffer, and 15,000 cpm from each lysate was used to do immunoprecipitation with anti-gp16 antiserum according to the procedure of McNicol et al (21).…”

Section: Methodsmentioning

confidence: 99%

Purification and Characterization of the Small Subunit of Phage T4 Terminase, gp16, Required for DNA Packaging

Lin

Simon

Black

1997

Journal of Biological Chemistry

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Phage T4 terminase is an enzyme that binds to the portal protein of proheads and cuts and packages concatemeric DNA. The T4 terminase is composed of two subunits, gene products (gp) 16 and 17. The role of the small subunit, gp16, in T4 DNA packaging is not well characterized. We developed a new purification procedure to obtain large quantities of purified gp16 from an overexpression vector. The pure protein is found in two molecular weight forms, due to specific C-terminal truncation, displays in vitro packaging activity, and binds but does not hydrolyze ATP. gp16 forms specific oligomers, rings, and side-by-side double rings, as judged by native polyacrylamide gel electrophoresis and scanning transmission electron microscopy measurements. Packaging of DNA into most dsDNA 1 bacteriophage heads requires an enzyme, terminase, which interacts with the portal vertex of the prohead and concatemeric DNA to form a packaging machine. Terminases in most of the phages contain two subunits. The large subunit generally has DNA-dependent ATPase and endonuclease activities, whereas the DNA-binding specificity resides in the small subunit (cf. Ref. 1). terminase specifically binds and cuts at a unique cos site to leave 12-base 5Ј protruding complementary ends at both termini (2, 3). For phages P1 or P22, the terminases bind and cut specifically near an initiation packaging (pac) site and then generate nonspecific ends, which result from processive headful packaging (4, 5).Although it was first established in phage T4 that the mature DNA ends result from headful packaging, in the case of T4 the mechanism of DNA end formation in packaging is less well defined (6). In fact, the phage T4 terminase displays many of the features of other phage terminases, including the small (gp16) and large (gp17) subunit structure (1, 7). Our genetic studies implicate gp16, the small subunit of T4 terminase, in amplifying a gene 17-gene 19 fragment. This is achieved by recombination following alignment of two homologous 24-base pair segments within gene 16 and gene 19 in T4 Hp17 (amplification) mutants. A synapsis model was proposed to correlate this novel activity with the known role of gene 16 in initiation of DNA packaging and in controlling activity of gp17, the terminase large subunit. This amplification suggests DNA binding by gp16 whose sequence specificity remains to be assessed (8, 9).ATP hydrolysis is required for phage in vitro DNA packaging (1, 10). ATP not only provides an energy source for DNA translocation into the prohead, but also acts as an allosteric effector to control terminase holoenzyme specificity (11). terminase has two ATP binding sites, where the high affinity site is located in the large subunit, and the low affinity site exists in the small subunit in which a weak ATPase activity was detected (12-14). It is possible that ATP binding to the terminase small subunit may serve mainly as an allosteric effector rather than in energy transduction. Thus in the Bacillus subtilis phage SPP1, the small subunit binds but does not ...

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A mutation which bypasses the requirement for p24 in bacteriophage T4 capsid morphogenesis

Cited by 36 publications

References 29 publications

Structural and functional similarities between the capsid proteins of bacteriophages T4 and HK97 point to a common ancestry

Structural and functional similarities between the capsid proteins of bacteriophages T4 and HK97 point to a common ancestry

Phylogeny of the Major Head and Tail Genes of the Wide-Ranging T4-Type Bacteriophages

Purification and Characterization of the Small Subunit of Phage T4 Terminase, gp16, Required for DNA Packaging

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