Document 0872
 DOCN  M9540872
 TI    Mechanism of interferon action: RNA-binding activity of full-length and
       R-domain forms of the RNA-dependent protein kinase PKR--determination of
       KD values for VAI and TAR RNAs.
 DT    9504
 AU    McCormack SJ; Samuel CE; Department of Biological Sciences, University
       of California,; Santa Barbara 93106.
 SO    Virology. 1995 Jan 10;206(1):511-9. Unique Identifier : AIDSLINE
       MED/95133187
 AB    The RNA-binding activity of the interferon-inducible, RNA-dependent
       protein kinase PKR, expressed from the human PKR cDNA, was quantitated
       using a gel mobility-shift assay. The N-terminal R-domain truncation
       Wt(1-243) and the full-length catalytic mutant K296R(21-551) were
       analyzed for their abilities to bind adenovirus VAI RNA, human
       immunodeficiency virus TAR RNA, and the synthetic homopolymer pI:pC RNA.
       The N-terminal 243 amino acid residue form of PKR [Wt(1-243)] bound VAI
       RNA with similar affinity as the 551 amino acid residue full-length
       catalytic mutant [K296R(1-551)]. The dissociation constant for VAI RNA
       was approximately 2 x 10(-9) M for both the K296R(1-551) and Wt(1-243)
       proteins. The K64E mutation significantly impaired the VAI RNA-binding
       activity as measured with the full-length double-point mutant PKR
       protein, K64E/K296R(1-551). Using a gel-shift competition assay, the
       dissociation constants of K296R(1-551) and Wt(1-243) for VAI(1-160) RNA
       and pI:pC RNA were comparable. By contrast, the dissociation constants
       of K296R(1-551) and Wt(1-243) for TAR(1-82) RNA were both about 1 x
       10(-7) M. These results suggest that the RNA-binding affinity of PKR is
       approximately 100-fold lower for TAR RNA than for either VAI RNA or
       pI:pC RNA and that the full-length and N-terminal R-domain forms of PKR
       bind RNA with similar affinity.
 DE    Adenoviridae/GENETICS  HIV/GENETICS  HIV Long Terminal Repeat/GENETICS
       Interferons/*PHARMACOLOGY  Protein Binding  Protein-Serine-Threonine
       Kinases/*METABOLISM  Recombinant Proteins/METABOLISM  RNA Probes  RNA,
       Viral/*METABOLISM  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).