Identification of a calmodulin-binding and inhibitory peptide domain in the HIV-1 transmembrane glycoprotein.
A number of studies suggest a critical role of the HIV-1 envelope glycoprotein in cytopathogenesis, but the detailed mechanisms of cell injury remain to be defined. HIV-1 envelope proteins associate with the host cell membrane, and studies have demonstrated that HIV perturbs membrane structure and function. We describe here a structurally conserved region of the HIV-1 transmembrane protein (TM) that displays functional properties of target regions of proteins that interact directly with calcium-saturated calmodulin as part of cellular response cascades. The synthetic peptide homolog encompassing the carboxyl terminus (amino acid residues 828-855) of HIV-1 TM protein (LLP-1) is shown in standard in vitro assays to bind efficiently to purified calmodulin (CaM) and to inhibit in vitro CaM-mediated stimulation of phosphodiesterase activity. This suggests that this peptide homolog binds to CaM at affinities similar to those reported for a reference CaM-binding peptide. In addition, the CaM-dependent process of phospholipid synthesis can be inhibited in cell cultures by exogenous addition of the LLP-1. Finally, we have shown that the full-length TM protein binds CaM, whereas a truncated TM protein lacking the LLP-1 segment does not bind CaM. These results suggest a novel mechanism of viral cytopathogenesis mediated by the interaction of HIV-1 TM protein with cellular CaM, that could lead to an uncoupling of critical cellular signal transduction pathways.
Miller
M A
MA
Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pennsylvania 15261.
Mietzner
T A
TA
Cloyd
M W
MW
Robey
W G
WG
Montelaro
R C
RC
D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D002147:Calmodulin / Q000378:metabolism*; D002460:Cell Line; D003588:Cytopathogenic Effect, Viral / Q000235:genetics / Q000502:physiology; D015686:Gene Products, env / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000235:genetics / Q000378:metabolism; D010743:Phospholipids / Q000096:biosynthesis; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology
D002147:Calmodulin; D015686:Gene Products, env; D010446:Peptide Fragments; D010743:Phospholipids; D010727:Phosphoric Diester Hydrolases