Specific Cross-linking of Capsid Proteins to Virus RNA by Ultraviolet Irradiation of Poliovirus

Abstract

Poliovirus was irradiated with UV light under conditions causing .apprx. 5% cross-linking of capsid protein to virus RNA. Cross-linked RNA-protein complexes, freed from unbound protein, were treated with nuclease and then analyzed on sodium dodecyl sulfate-polyacrylamide gels. The smallest capsid polypeptide VP4 was associated with the RNA to the greatest degree, followed by VP2 and VP1, while VP3 was attached only in trace amounts. Low radiation doses, which produced cross-linking of RNA to protein, did not cause breakdown of the virus particles or conformational changes of the capsid as examined physically and serologically. Higher doses caused structural alterations of the virus capsid.