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Tat peptide‐calmodulin binding studies and bioinformatics of HIV‐1 protein–calmodulin interactions
Author(s) -
McQueen Peter,
Donald Lynda J.,
Vo Thach N.,
Nguyen Dung H.,
Griffiths Heather,
Shojania Shaheen,
Standing Kenneth G.,
O'Neil Joe D.
Publication year - 2011
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.23048
Subject(s) - calmodulin , melittin , calmodulin binding proteins , peptide , biochemistry , target peptide , transactivation , proteome , plasma protein binding , binding site , biology , binding protein , calcium binding protein , chemistry , transcription factor , calcium , gene , enzyme , organic chemistry
The human immunodeficiency virus type 1 (HIV‐1) genome encodes 18 proteins and 2 peptides. Four of these proteins encode high‐affinity calmodulin‐binding sites for which direct interactions with calmodulin have already been described. In this study, the HIV‐1 proteome is queried using an algorithm that predicts calmodulin‐binding sites revealing seven new putative calmodulin‐binding sites including residues 34–56 of the transactivator of transcription (Tat). Tat is a 101‐residue intrinsically disordered RNA‐binding protein that plays a central role in the regulation of HIV‐1 replication. Interactions between a Tat peptide (residues 34–56), melittin, a well‐characterized calmodulin‐binding peptide, and calmodulin were examined by direct binding studies, mass spectrometry, and fluorescence. The Tat peptide binds to both calcium‐saturated and apo‐calmodulin with a low micromolar affinity. Conformational changes induced in the Tat peptide were determined by circular dichroism, and residues in calmodulin that interact with the peptide were identified by HSQC NMR spectroscopy. Multiple interactions between HIV‐1 proteins and calmodulin, a highly promiscuous signal transduction hub protein, may be an important mechanism by which the virus controls cell physiology. Proteins 2011; © 2011 Wiley‐Liss, Inc.