Document 0512
 DOCN  M9590512
 TI    Solution structure of the hydrophilic region of HIV-1 encoded virus
       protein U (Vpu) by CD and 1H NMR spectroscopy.
 DT    9509
 AU    Wray V; Federau T; Henklein P; Klabunde S; Kunert O; Schomburg D;
       Schubert U; Department of Molecular Structure Research, Institute of;
       Biotechnological Research, Braunschweig, Germany.
 SO    Int J Pept Protein Res. 1995 Jan;45(1):35-43. Unique Identifier :
       AIDSLINE MED/95293475
 AB    The HIV-1 specific Vpu is a class I oligomeric membrane phosphoprotein
       of unknown structure and mechanism. The first experimental evidence for
       the position of secondary structural elements present in the hydrophilic
       C-terminal region of Vpu under various solution regimes is reported. CD
       data for nine overlapping 15 amino-acid fragments and 3 longer fragments
       indicate the presence of only transitory amounts of stable structure in
       aqueous solution alone, while with increasing trifluoroethanol content
       limiting structures were found indicating two helical segments in the
       hydrophilic region of Vpu. These limiting structures were more precisely
       defined from a detailed study of Vpu41-58, Vpu52-74 and Vpu63-81, by a
       combination of 2D 1H NMR spectroscopy, distance geometry, and restrained
       molecular dynamics and energy minimization calculations. Sets of
       low-energy conformations compatible with the quantitative NOE data
       indicate that Vpu41-58 has an alpha-helix from residues 42 to 50 while a
       second helix is found for Vpu52-74 from residues 57 to 69. Vpu63-81
       shows only the presence of a single reverse turn at residues 74 to 77,
       without any evidence of helix, under the same conditions. From CD
       measurements the first helix extends back to residue 30 and is connected
       to the N-terminal anchor of Vpu. Thus the hydrophilic region of Vpu
       consists of two alpha-helices joined by a flexible region of 6 or 7
       residues, which contains the phosphoacceptor sites of Vpu at positions
       52 and 56. The second helix is followed by a single reverse turn and a
       flexible C-terminus.
 DE    Amino Acid Sequence  Circular Dichroism  Gene Products,
       vpu/*CHEMISTRY/GENETICS  Genetic Code  *Helix-Loop-Helix Motifs  Models,
       Chemical  Molecular Sequence Data  Molecular Structure  Nuclear Magnetic
       Resonance  Peptide Fragments/CHEMISTRY  *Protein Structure, Secondary
       Solubility  Solutions  Support, Non-U.S. Gov't  Water/CHEMISTRY  JOURNAL
       ARTICLE

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