Regulation of coat protein polymerization by the scaffolding protein of bacteriophage P22

Journal Article · Wed Oct 01 04:00:00 EDT 1980 · Biophys. J.; (United States)

DOI:https://doi.org/10.1016/S0006-3495(80)84963-0· OSTI ID:6796010

Fuller, M T; King, J

In the morphogenesis of double stranded DNA phages, a precursor protein shell empty of DNA is first assembled and then filled with DNA. The assembly of the correctly dimensioned precursor shell (procapsid) of Salmonella bacteriophage P22 requires the interaction of some 420 coat protein subunits with approx. 200 scaffolding protein subunits to form a double shelled particle with the scaffolding protein on the inside. In the course of DNA packaging, all of the scaffolding protein subunits exit from the procapsid and participate in further rounds of procapsid assembly. To study the mechanism of shell assembly we have purified the coat and scaffolding protein subunits by selective dissociation of isolated procapsids. Both proteins can be obtained as soluble sununits in Tris buffer at near neutral pH. The coat protein sedimented in sucrose gradients as a roughly spherical monomer, while the scaffolding protein sedimented as if it were an elongated monomer. When the two proteins were mixed together in 1.5 M guanidine hydrochloride and dialyzed back to buffer at room temperature, procapsids formed which were very similar in morphology, sedimentation behavior, and protein composition to procapsids formed in vivo. Incubation of either protein alone under the same conditions did not yield any large structures. We interpret these results to mean that the assembly of the shell involves a switching of both proteins from their nonaggregating to their aggregating forms through their mutual interaction. The results are discussed in terms of the general problem of self-regulated assembly and the control of protein polymerization in morphogenesis.

• Research Organization: Massachusetts Inst. of Tech., Cambridge
• OSTI ID: 6796010
• Journal Information: Biophys. J.; (United States), Journal Name: Biophys. J.; (United States) Vol. 32:1; ISSN BIOJA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
550700 -- Microbiology
550800 -- Morphology
59 BASIC BIOLOGICAL SCIENCES
BACTERIOPHAGES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL PATHWAYS
BIOSYNTHESIS
CAPSULES
CHEMICAL REACTIONS
CONTAINERS
DNA
DYNAMIC FUNCTION STUDIES
KINETICS
MEMBRANES
MICROORGANISMS
MOLECULAR STRUCTURE
MORPHOLOGY
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PARASITES
POLYMERIZATION
REACTION KINETICS
SYNTHESIS
VIRUSES