Moloney murine leukemia virus genomic RNA packaged in the absence of a full complement of wild type nucleocapsid protein.
The current model for MLV genomic RNA (gRNA) packaging predicts that of the thousands of Gag proteins in a budding virion, only a small number (≤1%) may be necessary to recruit gRNA. Here, we examined the threshold limits of functional Gag required to package gRNA using wild-type (WT) and packaging deficient mutant nucleocapsid (NC) phenotypically mixed virions. Although gRNA packaging was severely diminished for the NC mutant, the residual encapsidated RNA dimer displayed motility on gels, thermostability, and integrity that was indistinguishable from that of WT. In phenotypically mixed virions, gRNA encapsidation recovered to within approximately two-fold of WT levels when the amount of WT NC was 5-10% of the total. Our results demonstrate that NC's roles in gRNA dimerization and packaging are genetically separable. Additionally, MLV gRNA packaging does not require 100% WT NC, but the amount of functional NC required is greater than the predicted minimum.
Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI 48109, USA.
Silas F
SF
Johnson
Eric L
EL
Garcia
Michael F
MF
Summers
Alice
A
Telesnitsky
D016475:3T3 Cells; D000818:Animals; D002460:Cell Line; D015683:Gene Products, gag / Q000235:genetics / Q000378:metabolism; D016679:Genome, Viral; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008979:Moloney murine leukemia virus / Q000235:genetics* / Q000378:metabolism*; D019251:Nucleocapsid / Q000235:genetics / Q000378:metabolism; D019590:Nucleocapsid Proteins / Q000235:genetics / Q000378:metabolism*; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism*; D019065:Virus Assembly / Q000235:genetics / Q000502:physiology*
C468293:Gag protein p12, moloney murine leukemia virus; D015683:Gene Products, gag; D019590:Nucleocapsid Proteins; D012367:RNA, Viral