Conformational transformations in the protein lattice of phage P22 procapsids.

AUTOR(ES)

Galisteo, M L

RESUMO

During the packaging of double-stranded DNA by bacterial viruses, the precursor procapsid loses its internal core of scaffolding protein and undergoes a substantial expansion to form the mature virion. Here we show that upon heating, purified P22 procapsids release their scaffolding protein subunits, and the coat protein lattice expands in the absence of any other cellular or viral components. Following these processes by differential scanning calorimetry revealed four different transitions that correlated with structural transitions in the coat protein shells. Exit of scaffolding protein from the procapsid occurred reversibly and just above physiological temperature. Expansion of the procapsid lattice, which was exothermic, occurred after the release of scaffolding protein. Partial denaturation of coat subunits within the intact shell structure was detected prior to the major endothermic event. This major endotherm occurred above 80 degrees C and represents particle breakage and irreversible coat protein denaturation. The results indicate that the coat subunits are designed to form a metastable precursor lattice, which appears to be separated from the mature lattice by a kinetic barrier.

Documentos Relacionados

• The Circularity of the Phage P22 Linkage Map
• Fine Structure Genetic and Physical Map of the Phage P22 Tail Protein Gene
• Genetic Properties of Temperature-Sensitive Folding Mutants of the Coat Protein of Phage P22
• GroEL binds a late folding intermediate of phage P22 coat protein
• Mutations That Improve the ANT Promoter of Salmonella Phage P22