Enzymatic regulation of pattern: BMP4 binds CUB domains of Tolloids and inhibits proteinase activity.
In Xenopus embryos, a dorsal-ventral patterning gradient is generated by diffusing Chordin/bone morphogenetic protein (BMP) complexes cleaved by BMP1/Tolloid metalloproteinases in the ventral side. We developed a new BMP1/Tolloid assay using a fluorogenic Chordin peptide substrate and identified an unexpected negative feedback loop for BMP4, in which BMP4 inhibits Tolloid enzyme activity noncompetitively. BMP4 binds directly to the CUB (Complement 1r/s, Uegf [a sea urchin embryonic protein] and BMP1) domains of BMP1 and Drosophila Tolloid with high affinity. Binding to CUB domains inhibits BMP4 signaling. These findings provide a molecular explanation for a long-standing genetical puzzle in which antimorphic Drosophila tolloid mutant alleles displayed anti-BMP effects. The extensive Drosophila genetics available supports the relevance of the interaction described here at endogenous physiological levels. Many extracellular proteins contain CUB domains; the binding of CUB domains to BMP4 suggests a possible general function in binding transforming growth factor-beta (TGF-beta) superfamily members. Mathematical modeling indicates that feedback inhibition by BMP ligands acts on the ventral side, while on the dorsal side the main regulator of BMP1/Tolloid enzymatic activity is the binding to its substrate, Chordin.
Lee
Hojoon X
HX
Howard Hughes Medical Institute and Department of Biological Chemistry, University of California at Los Angeles, Los Angeles, California 90095, USA.
Mendes
Fabio A
FA
Plouhinec
Jean-Louis
JL
De Robertis
Edward M
EM
D000818:Animals; D019521:Body Patterning; D055395:Bone Morphogenetic Protein 1 / Q000037:antagonists & inhibitors*; D055415:Bone Morphogenetic Protein 4 / Q000378:metabolism*; D015923:Complement C1r / Q000378:metabolism; D003173:Complement C1s / Q000378:metabolism; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster; D004625:Embryo, Nonmammalian; D004791:Enzyme Inhibitors / Q000378:metabolism*; D025461:Feedback, Physiological; D017434:Protein Structure, Tertiary; D055394:Tolloid-Like Metalloproteinases / Q000378:metabolism*; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology*
D055415:Bone Morphogenetic Protein 4; D029721:Drosophila Proteins; D004791:Enzyme Inhibitors; D029867:Xenopus Proteins; D055394:Tolloid-Like Metalloproteinases; D015923:Complement C1r; D003173:Complement C1s; D055395:Bone Morphogenetic Protein 1