Molecular analysis of the epidermal growth factor-like short consensus repeat domain-mediated protein-protein interactions: dissection of the CD97-CD55 complex.
Epidermal growth factor-like (EGF) and short consensus repeat (SCR) domains are commonly found in cell surface and soluble proteins that mediate specific protein-protein recognition events. Unlike the immunoglobulin (Ig) superfamily, very little is known about the general properties of intermolecular interactions encoded by these common modules, and in particular, how specificity of binding is achieved. We have dissected the binding of CD97 (a member of the EGF-TM7 family) to the complement regulator CD55, two cell surface modular proteins that contain EGF and SCR domains, respectively. We demonstrate that the interaction is mediated solely by these domains and is characterized by a low affinity (86 microm) and rapid off-rate (at least 0.6 s(-1)). The interaction is Ca(2+) -dependent but is unaffected by glycosylation of the EGF domains. Using biotinylated multimerized peptides in cell binding assays and surface plasmon resonance, we show that a CD97-related EGF-TM7 molecule (termed EMR2), differing by only three amino acids within the EGF domains, binds CD55 with a K(D) at least an order of magnitude weaker than that of CD97. These results suggest that low affinity cell-cell interactions may be a general feature of highly expressed cell surface proteins and that specificity of SCR-EGF binding can be finely tuned by a small number of amino acid changes on the EGF module surface.
Lin
H H
HH
Sir William Dunn School of Pathology, South Parks Road, Oxford, United Kingdom.
Stacey
M
M
Saxby
C
C
Knott
V
V
Chaudhry
Y
Y
Evans
D
D
Gordon
S
S
McKnight
A J
AJ
Handford
P
P
Lea
S
S
D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD; D001665:Binding Sites; D018958:CD55 Antigens / Q000737:chemistry* / Q000378:metabolism*; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D016384:Consensus Sequence; D006224:Cricetinae; D004815:Epidermal Growth Factor / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D043562:Receptors, G-Protein-Coupled; D020449:Repetitive Sequences, Amino Acid; D017386:Sequence Homology, Amino Acid; D020349:Surface Plasmon Resonance
C412456:ADGRE2 protein, human; C095004:ADGRE5 protein, human; D015703:Antigens, CD; D018958:CD55 Antigens; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D043562:Receptors, G-Protein-Coupled; D004815:Epidermal Growth Factor; D002118:Calcium