HIV-1 matrix protein repositioning in nucleocapsid region fails to confer virus-like particle assembly.
The HIV-1 matrix (MA) protein is similar to nucleocapsid (NC) proteins in its propensity for self-interaction and association with RNA. Here we report on our finding that replacing MA with NC results in the production of wild type (wt)-level RNA and virus-like particles (VLPs). In contrast, constructs containing MA as a substitute for NC are markedly defective in VLP production and form virions with lower densities than wt, even though their RNA content is over 50% that of wt level. We also noted that a DeltaMN mutant lacking both MA and NC produces a relatively higher amount of VLPs than those in which MA was substituted for NC. Although DeltaMN contains approximately 30% the RNA of wt, it still exhibits virion densities equal (or very similar) to those of wt. The data suggest that neither NC nor RNA are major virion density determinants. Furthermore, we noted that NC(ZIP)--a NC replacement with a leucine zipper dimerization motif--produces VLPs as efficiently as wt. However, the markedly reduced assembly efficiency of NC(ZIP) is associated with the formation of VLPs with densities slightly lower than those of wt following MA removal, suggesting that (a) MA is required to help the inserted leucine zipper motif perform efficient Gag multimerization, and (b) MA plays a role in the virus assembly process.
Department of Medical Research and Education, Taipei Veterans General Hospital, Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan.
Ching-Yuan
CY
Chang
Yu-Fen
YF
Chang
Shiu-Mei
SM
Wang
Ying-Tzu
YT
Tseng
Kuo-Jung
KJ
Huang
Chin-Tien
CT
Wang
D002460:Cell Line; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009154:Mutation; D019251:Nucleocapsid / Q000235:genetics / Q000378:metabolism*; D012367:RNA, Viral / Q000378:metabolism*; D014763:Viral Matrix Proteins / Q000235:genetics / Q000378:metabolism*; D014771:Virion / Q000378:metabolism*; D019065:Virus Assembly; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism
D012367:RNA, Viral; D014763:Viral Matrix Proteins; D054301:gag Gene Products, Human Immunodeficiency Virus