Infectivity of Moloney murine leukemia virus defective in late assembly events is restored by late assembly domains of other retroviruses.
The p12 region of the Moloney murine leukemia virus (M-MuLV) Gag protein contains a PPPY motif important for efficient virion assembly and release. To probe the function of the PPPY motif, a series of insertions of homologous and heterologous motifs from other retroviruses were introduced at various positions in a mutant gag gene lacking the PPPY motif. The assembly defects of the PPPY deletion mutant could be rescued by insertion of a wild-type PPPY motif and flanking sequences at several ectopic positions in the Gag protein. The late assembly domain (L-domain) of Rous sarcoma virus (RSV) or human immunodeficiency virus type 1 (HIV-1) could also fully or partially restore M-MuLV assembly when introduced into matrix, p12, or nucleocapsid domains of the mutant M-MuLV Gag protein lacking the PPPY motif. Strikingly, mutant viruses carrying the RSV or the HIV-1 L-domain at the original location of the deleted PPPY motif were replication competent in rodent cells. These data suggest that the PPPY motif of M-MuLV acts in a partially position-independent manner and is functionally interchangeable with L-domains of other retroviruses. Electron microscopy studies revealed that deletion of the entire p12 region resulted in the formation of tube-like rather than spherical particles. Remarkably, the PPPY deletion mutant formed chain structures composed of multiple viral particles linked on the cell surface. Many of the mutants with heterologous L-domains released virions with wild-type morphology.
Yuan
B
B
Integrated Program in Cellular, Molecular and Biophysical Studies, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
Campbell
S
S
Bacharach
E
E
Rein
A
A
Goff
S P
SP
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D004279:DNA, Viral / Q000096:biosynthesis; D003673:Defective Viruses / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D015683:Gene Products, gag / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051379:Mice; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D008979:Moloney murine leukemia virus / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D016254:Mutagenesis, Insertional; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012190:Retroviridae / Q000737:chemistry / Q000235:genetics; D017422:Sequence Analysis, DNA; D014162:Transfection; D014771:Virion / Q000737:chemistry / Q000378:metabolism; D019065:Virus Assembly
D004279:DNA, Viral; D015683:Gene Products, gag; D011993:Recombinant Fusion Proteins