[The Point Mutation in NOGGIN2 Protein That Enhances Its Ability to Bind Activin]

Earlier we have revealed the ability of Noggin family proteins to bind a member of the TUF-β superfamily, ActivinB, and to repress the Activin-dependent Smad2 signaling cascade. In the present work we have characterized a mutant of the Xenopus laevis Noggin2, bearing the substitution W203R. We have shown that this point mutation enhances the affinity of Noggin2 to ActivinB, while weakens its affinity to BMP. Consistently, we have shown that W203 R mutant inhibits Smad2 signaling cascade more efficiently than the wild-type Noggin2. Interestingly, the mutation of human Noggin in the homologous position is associated with hereditary anomalies. The revealed effects of W203R substitution in Noggin2 demonstrate promising potential of such mutagenesis for generation of Noggin variants with enhanced affinity to different members of the TGF-β superfamily.