Functional genomic analysis reveals the utility of the I/LWEQ module as a predictor of protein:actin interaction.
The I/LWEQ module is a conserved sequence that we have identified as an actin-binding motif in the metazoan focal adhesion protein talin and the yeast protein Sla2p. Both of these proteins are associated with the actin cytoskeleton in cells. To better establish the value of the I/LWEQ module for prediction of actin-binding function, we have applied a functional genomics approach. Analysis of the 23 available I/LWEQ module sequences supports the division of I/LWEQ protein superfamily into four groups: (1) metazoan talin, (2) Dictyostelium discoideum talin homologs TalA/B, (3) metazoan Hip1p, and (4) yeast Sla2p. We show here that I/LWEQ modules from each major group bind to F-actin in vitro and that GFP-fusion proteins of the I/LWEQ modules of talin and Sla2p bind to F-actin in vivo. Therefore, the presence of an I/LWEQ module is strongly predictive of protein-actin interactions. The structural and functional conservation of the I/LWEQ module across the phylogenetic distance between cellular slime molds and mammals implies that the role of the I/LWEQ module is to connect diverse proteins involved in distinct cellular processes, including cell adhesion, cytoskeletal organization, and cell differentiation, to the actin cytoskeleton.
McCann
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Department of Biological Chemistry, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, Maryland, 21205-2185, USA.
Craig
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D000199:Actins / Q000378:metabolism*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D017124:Conserved Sequence / Q000502:physiology*; D006224:Cricetinae; D003598:Cytoskeletal Proteins; D003599:Cytoskeleton / Q000378:metabolism; D016208:Databases, Factual; D004023:Dictyostelium; D020224:Expressed Sequence Tags; D005656:Fungal Proteins / Q000737:chemistry* / Q000378:metabolism; D016678:Genome; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010802:Phylogeny; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D013329:Structure-Activity Relationship; D016608:Talin / Q000737:chemistry* / Q000378:metabolism
D000199:Actins; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D005656:Fungal Proteins; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; C082266:SLA2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D016608:Talin