| structure of the herpes simplex virus capsid: effects of extraction with guanidine hydrochloride and partial reconstitution of extracted capsids. | viral b capsids were purified from cells infected with herpes simplex virus type 1 and extracted in vitro with 2.0 m guanidine hydrochloride (guhcl). sodium dodecyl sulfate-polyacrylamide gel analyses demonstrated that extraction resulted in the removal of greater than 95% of capsid proteins vp22a and vp26 while there was only minimal (less than 10%) loss of vp5 (the major capsid protein), vp19, and vp23. electron microscopic analysis of extracted capsids revealed that the pentons and the materi ... | 1991 | 1846187 |
| thermal unfolding pathway for the thermostable p22 tailspike endorhamnosidase. | the conditions in which protein stability is biologically or industrially relevant frequently differ from those in which reversible denaturation is studied. the trimeric tailspike endorhamnosidase of phage p22 is a viral structural protein which exhibits high stability to heat, proteases, and detergents under a range of environmental conditions. its intracellular folding pathway includes monomeric and trimeric folding intermediates and has been the subject of detailed genetic analysis. to unders ... | 1991 | 2059632 |
| novel second-site suppression of a cold-sensitive defect in phage p22 procapsid assembly. | the dna packaging portal of the phage p22 procapsid is formed of 12 molecules of the 90,000 dalton gene 1 protein. the assembly of this dodecameric complex at a unique capsid vertex requires scaffolding subunits. the mechanism that ensures the location of the 12-fold symmetrical portal at only one of the 12 5-fold vertices of an icosahedral virus capsid presents a unique assembly problem, which, in some viruses, is solved by the portal also acting as initiator of procapsid assembly. phage p22 pr ... | 1990 | 2258936 |
| a late gene product of phage p22 affecting virus infectivity. | gene 14 is a recently discovered late gene of phage p22, mapping between the dna injection and head completion genes (p. youderian and m. susskind (1980), virology 107, 258-269). the gene 14 product has not been detected in phage particles. we have studied the defective phenotype of amber mutants in gene 14 to determine the role of gp14. the yield of physical particles from 14- infections is normal, but the infectivity of those particles is reduced by 60-80%. the noninfectious particles adsorb t ... | 1985 | 2998017 |
| bacteriophage concentration from water by filter chromatography. | the efficiency of an electropositive filter for membrane chromatography of viruses was examined using coliform phages t1, t4, lambda and salmonella phage p22. phages diluted in dechlorinated tap water were adsorbed to filters at neutral ph and eluted by 3% beef extract in 0.05 m glycine buffer at selected alkaline ph values. with exception of lambda phage, which displayed erratic adsorption behavior at any ph, all bacteriophages studied, adsorbed to filters with an efficiency of 97-100% at ph va ... | 1983 | 6677647 |
| structural studies of p22 phage, precursor particles, and proteins by laser raman spectroscopy. | for the study of the protein--protein and protein--nucleic acid interactions in the assembly of virus particles, laser raman spectra have been obtained in h2o and d2o solutions and as a function of temperature for the following salmonella phage p22 components: mature phage particles, isolated mature phage dna, mature protein shells empty of dna, precursor protein shells (procapsids), and purified coat, scaffolding and tail-spike proteins. the spectra confirm that the condensed dna within the pha ... | 1982 | 7138810 |
| structural transitions in the scaffolding and coat proteins of p22 virus during assembly and disassembly. | an in vitro system for investigating the assembly of the salmonella phage p22 has been exploited to elucidate the structural basis of recognition between scaffolding protein (gp8) and coat protein (gp5) subunits of the viral procapsid. raman spectroscopy and circular dichroism have been employed to examine structural thermostabilities of both gp8 and gp5 in native procapsids, and to characterize structural changes accompanying scaffolding exit, procapsid expansion, and shell disassembly. it is f ... | 1996 | 8605213 |
| crystal structure of phage p22 tailspike protein complexed with salmonella sp. o-antigen receptors. | the o-antigenic repeating units of lipopolysaccharides from salmonella serogroups a, b, and d1 serve as receptors for the phage p22 tailspike protein, which also has receptor destroying endoglycosidase (endorhamnosidase) activity, integrating the functions of both hemagglutinin and neuraminidase in influenza virus. crystal structures of the tailspike protein in complex with oligosaccharides, comprising two o-antigenic repeating units from salmonella typhimurium, salmonella enteritidis, and salmo ... | 1996 | 8855221 |
| measurement of the accurate mass of a 50 mda infectious virus. | bacteriophage p22 is believed to contain a total of 521 copies of 9 different proteins and a 41,724 base pair genome. despite its enormous size and complexity, phage p22 can be electrosprayed, and it remains intact in ultra-high vacuum where its molar mass distribution has been measured. | 2016 | 27501430 |
| contextual role of a salt bridge in the phage p22 coat protein i-domain. | the i-domain is a genetic insertion in the phage p22 coat protein that chaperones its folding and stability. of 11 acidic residues in the i-domain, seven participate in stabilizing electrostatic interactions with basic residues across elements of secondary structure, fastening the β-barrel fold. a hydrogen-bonded salt bridge between asp-302 and his-305 is particularly interesting as asp-302 is the site of a temperature-sensitive-folding mutation. the pka of his-305 is raised to 9.0, indicating t ... | 2016 | 27006399 |
| viral transmission dynamics at single-cell resolution reveal transiently immune subpopulations caused by a carrier state association. | monitoring the complex transmission dynamics of a bacterial virus (temperate phage p22) throughout a population of its host (salmonella typhimurium) at single cell resolution revealed the unexpected existence of a transiently immune subpopulation of host cells that emerged from peculiarities preceding the process of lysogenization. more specifically, an infection event ultimately leading to a lysogen first yielded a phage carrier cell harboring a polarly tethered p22 episome. upon subsequent div ... | 2015 | 26720743 |
| architecture of the complex formed by large and small terminase subunits from bacteriophage p22. | packaging of viral genomes inside empty procapsids is driven by a powerful atp-hydrolyzing motor, formed in many double-stranded dna viruses by a complex of a small terminase (s-terminase) subunit and a large terminase (l-terminase) subunit, transiently docked at the portal vertex during genome packaging. despite recent progress in elucidating the structure of individual terminase subunits and their domains, little is known about the architecture of an assembled terminase complex. here, we descr ... | 2015 | 26301600 |
| polyhead formation in phage p22 pinpoints a region in coat protein required for conformational switching. | eighteen single amino acid substitutions in phage p22 coat protein cause temperature-sensitive folding defects (tsf). three intragenic global suppressor (su) substitutions (d163g, t166i and f170l), localized to a flexible loop, rescue the folding of several tsf coat proteins. here we investigate the su substitutions in the absence of the original tsf substitutions. none of the su variant coat proteins displayed protein folding defects. individual su substitutions had little effect on phage produ ... | 2007 | 17680786 |
| phage p22 procapsids equilibrate with free coat protein subunits. | assembly of bacteriophage p22 procapsids has long served as a model for assembly of spherical viruses. historically, assembly of viruses has been viewed as a non-equilibrium process. recently alternative models have been developed that treat spherical virus assembly as an equilibrium process. here we have investigated whether p22 procapsid assembly reactions achieve equilibrium or are irreversibly trapped. to assemble a procapsid-like particle in vitro, pure coat protein monomers are mixed with ... | 2007 | 17067636 |
| quantitative analysis of multi-component spherical virus assembly: scaffolding protein contributes to the global stability of phage p22 procapsids. | assembly of the hundreds of subunits required to form an icosahedral virus must proceed with exquisite fidelity, and is a paradigm for the self-organization of complex macromolecular structures. however, the mechanism for capsid assembly is not completely understood for any virus. here we have investigated the in vitro assembly of phage p22 procapsids using a quantitative model specifically developed to analyze assembly of spherical viruses. phage p22 procapsids are the product of the co-assembl ... | 2006 | 16697406 |
| folding of phage p22 coat protein monomers: kinetic and thermodynamic properties. | to assemble into a virus with icosahedral symmetry, capsid proteins must be able to attain multiple conformations. whether this conformational diversity is achieved during folding of the subunit, or subsequently during assembly, is not clear. phage p22 coat protein offers an ideal model to investigate the folding of a monomeric capsid subunit since its folding is independent of assembly. our early studies indicated that p22 coat protein monomers could be folded into an assembly-competent state i ... | 2003 | 12951032 |