title: Analysis and identification of the Grem2 heparin/heparan sulfate-binding motif.
abstract: Bone morphogenetic proteins (BMPs) are regulated by extracellular antagonists of the DAN (differential screening-selected gene aberrative in neuroblastoma) family. Similar to the BMP ligands, certain DAN family members have been shown to interact with heparin and heparan sulfate (HS). Structural studies of DAN family members Gremlin-1 and Gremlin-2 (Grem2) have revealed a dimeric growth factor-like fold where a series of lysine residues cluster along one face of the protein. In the present study, we used mutagenesis, heparin-binding measurements, and cell surface-binding analysis to identify lysine residues that are important for heparin/HS binding in Grem2. We determined that residues involved in heparin/HS binding, while not necessary for BMP antagonism, merge with the heparin/HS-binding epitope of BMP2. Furthermore, the Grem2-BMP2 complex has higher affinity for heparin than the individual proteins and this affinity is not abrogated when the heparin/HS-binding epitope of Grem2 is attenuated. Overall, the present study shows that the Grem2 heparin/HS and BMP-binding epitopes are unique and independent, where, interestingly, the Grem2-BMP2 complex exhibits a significant increase in binding affinity toward heparin moieties that appear to be partially independent of the Grem2 heparin/HS-binding epitope.
authors.affiliation: Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati, Medical Sciences Building, Cincinnati, OH 45267, U.S.A.
authors.forename: Chandramohan
authors.initials: C
authors.lastname: Kattamuri
authors.affiliation: Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati, Medical Sciences Building, Cincinnati, OH 45267, U.S.A.
authors.forename: Kristof
authors.initials: K
authors.lastname: Nolan
authors.affiliation: Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati, Medical Sciences Building, Cincinnati, OH 45267, U.S.A. tom.thompson@uc.edu.
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Thompson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D055396:Bone Morphogenetic Protein 2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016466:CHO Cells; D003001:Cloning, Molecular; D003412:Cricetulus; D016207:Cytokines; D000939:Epitopes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006493:Heparin / Q000737:chemistry* / Q000378:metabolism; D006497:Heparan Sulfate / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship
chemical_list: D055396:Bone Morphogenetic Protein 2; D016207:Cytokines; D000939:Epitopes; D006493:Heparin; D006497:Heparan Sulfate; D036341:Intercellular Signaling Peptides and Proteins; D011994:Recombinant Proteins; C525718:BMP2 protein, human; C495107:GREM2 protein, human
keywords: BMP; Gremlin-2; heparin; transforming growth factors