Localization of self-interacting domains within betaretrovirus Gag polyproteins

• Published in: Virology (New York, N.Y.) N.Y.), 2005-02, Vol.332 (2), p.659-666
• Main Authors: Zábranský, Aleš, Sakalian, Michael, Pichová, Iva
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Assembly; Base Sequence; Betaretrovirus; Binding Sites; Capsid; DNA Primers; Escherichia coli - genetics; Gag; Gene Products, gag - chemistry; Gene Products, gag - genetics; Gene Products, gag - metabolism; M-PMV; Mammary Tumor Virus, Mouse - genetics; Mammary Tumor Virus, Mouse - metabolism; Mason-Pfizer monkey virus; Mason-Pfizer monkey virus - metabolism; MMTV; Molecular Sequence Data; Mouse mammary tumor virus; Plasmids; Polymerase Chain Reaction; Protein–protein interaction; Two-hybrid
• ISSN: 0042-6822; 1096-0341
• DOI: 10.1016/j.virol.2004.12.007

The Betaretrovirus genus is characterized by the ability to preassemble immature capsids within the cytoplasm. For Mason–Pfizer monkey virus (M-PMV) this ability depends in part upon the unique Internal Scaffold Domain (ISD) within the p12 region of Gag. In this study, we have further characterized the ability of M-PMV p12 to promote Gag–Gag interaction and have examined the Gag polyprotein of the related mouse mammary tumor virus (MMTV) to potentially identify a region with equivalent function. Using the yeast two-hybrid system, we confirmed that both Gag polyproteins strongly interact, primarily through the CA-NC regions, but also through additional domains N-terminal to CA. For M-PMV, this auxiliary interaction domain was p12. For MMTV, no single strongly self-interacting protein was identified. Instead, MMTV Gag appears to utilize the weak contributions of several protein domains to support the main interaction of its CA-NC. Our findings suggest that, in addition to the canonical NC “I-domain” interaction, MMTV Gag self-association results from the concerted action of multiple regions of the polyprotein while M-PMV Gag relies mainly on its p12 domain.