       Document 0662
 DOCN  M9640662
 TI    Evidence for a second function of the MA sequence in the Rous sarcoma
       virus Gag protein.
 DT    9604
 AU    Parent LJ; Wilson CB; Resh MD; Wills JW; Department of Medicine,
       Pennsylvania State University College of; Medicine, Hershey 17033, USA.
 SO    J Virol. 1996 Feb;70(2):1016-26. Unique Identifier : AIDSLINE
       MED/96135214
 AB    During retrovirus assembly, Gag proteins bind to the inner leaflet of
       the plasma membrane to initiate the budding process. The molecular basis
       of this protein-lipid interaction is poorly understood. For the human,
       immunodeficiency virus type 1 Gag protein, we recently reported that the
       membrane-binding domain resides within the N-terminal 31 amino acids and
       consists of two components: myristate and a cluster of basic residues,
       which together promote membrane binding in vitro and budding in vivo (W.
       Zhou, L. J. Parent, J. W. Wills, and M. D. Resh, J. Virol. 68:2556-2569,
       1994). The positively charged residues associate electrostatically with
       acidic phospholipids to stabilize membrane binding, while myristate
       provides membrane-binding energy via hydrophobic interactions. Here we
       demonstrate that the human immunodeficiency virus type 1 Gag
       membrane-binding domain can fully replace the membrane-targeting
       function of the N-terminal 100 residues of the non-myristylated Rous
       sarcoma virus (RSV) Gag protein. To further explore the importance of
       myristate and basic residues in membrane binding, we developed a
       gain-of-function assay whereby budding was restored to defective mutants
       of RSV Gag. Detailed mutational analysis revealed that the position,
       number, and context of charged residues are crucial to budding.
       Myristate provides additional membrane-binding energy, which is critical
       when a Gag protein is near the threshold of stable membrane association.
       Finally, viruses with altered matrix (MA) proteins that are
       noninfectious, even though they produce particles with high efficiency,
       were identified. Thus, we present the first evidence that the RSV MA
       sequence plays two distinct roles, membrane binding during particle
       assembly and a second, as yet undefined function required for viral
       infectivity.
 DE    Amino Acid Sequence  Base Sequence  Binding Sites  DNA, Viral  Gene
       Products, gag/GENETICS/*PHYSIOLOGY  Human  HIV-1/GENETICS/*PHYSIOLOGY
       Molecular Sequence Data  Mutagenesis, Insertional  Myristic
       Acids/METABOLISM  Sarcoma Viruses,
       Avian/GENETICS/*PHYSIOLOGY/PATHOGENICITY  Support, Non-U.S. Gov't
       Support, U.S. Gov't, P.H.S.  JOURNAL ARTICLE

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

