Document 0721
 DOCN  M95A0721
 TI    Mutational analysis of the conserved cysteine residues in the simian
       immunodeficiency virus matrix protein.
 DT    9510
 AU    Gonzalez SA; Affranchino JL; Centro de Virologia Animal (CEVAN-CONICET),
       Buenos Aires,; Argentina.
 SO    Virology. 1995 Jul 10;210(2):501-7. Unique Identifier : AIDSLINE
       MED/95343565
 AB    The matrix protein (MA) of human and simian immunodeficiency viruses
       (HIV and SIV) is encoded by the amino-terminal region of the Gag
       precursor and has been suggested to be involved in different processes
       during the early and late stages of the virus life cycle. The MA protein
       of SIV contains three cysteine residues at positions 57, 83, and 87,
       which are also highly conserved among HIV-2 isolates. In order to study
       the functional significance of these residues in virus morphogenesis, a
       series of mutations affecting the cysteines of SIV MA were introduced
       into a gag-protease construct and expressed in the vaccinia vector
       system. The MA mutants were assayed for their ability to synthesize and
       process the Gag polyprotein precursor as well as to release particles
       into the culture medium. In addition, the incorporation of the envelope
       glycoprotein (Env) into the Gag-made particles was investigated.
       Substitution of alanine for cysteine 87 had little effect on particle
       release and Env glycoprotein association. By contrast, the individual
       replacement of cysteines 57 or 83 by alanine, as well as the
       simultaneous mutation of cysteines 83 and 87, significantly reduced the
       ability of Gag polypeptides to produce extracellular particles. Assembly
       into particles appeared to be also affected, albeit to a lesser extent,
       when both cysteines 57 and 83 were replaced by alanine. Furthermore,
       substitution of cysteine 83 in the SIV MA domain was found to be
       detrimental to Gag polyprotein processing. Analysis of the Env
       glycoprotein association with recombinant particles revealed that this
       process was moderately affected in the case of the double mutants
       lacking cysteines 57 and 83, or cysteines 57 and 87, and the
       cysteine-minus triple mutant. Our results suggest that the conserved
       cysteines 57 and 83 in the MA domain are important for efficient SIV Gag
       particle production.
 DE    Amino Acid Sequence  Base Sequence  Cell Line  Conserved
       Sequence/*GENETICS  Cysteine/*PHYSIOLOGY  *DNA Mutational Analysis  Gene
       Products, env/METABOLISM  Gene Products, gag/BIOSYNTHESIS/METABOLISM
       Genes, gag/GENETICS  Genetic Vectors/GENETICS  HIV Envelope Protein
       gp120/ANALYSIS  Molecular Sequence Data  Morphogenesis
       Mutation/PHYSIOLOGY  Protein Processing, Post-Translational  Support,
       Non-U.S. Gov't  SIV/GENETICS/*PHYSIOLOGY  Vaccinia Virus/GENETICS  Viral
       Matrix Proteins/*GENETICS/PHYSIOLOGY  Virion  Virus
       Replication/*GENETICS  JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).