The C313Y Piedmontese mutation decreases myostatin covalent dimerisation and stability

<p>Abstract</p> <p>Background</p> <p>Myostatin is a key negative regulator of muscle growth and development, whose activity has important implications for the treatment of muscle wastage disorders. Piedmontese cattle display a double-muscled phenotype associated with the expression of C313Y mutant myostatin. <it>In vivo</it>, C313Y myostatin is proteolytically processed, exported and circulated extracellularly but fails to correctly regulate muscle growth. The C313Y mutation removes the C313-containing disulphide bond, an integral part of the characteristic TGF-β cystine-knot structural motif.</p> <p>Results</p> <p>Here we present <it>in vitro </it>analysis of the structure and stability of the C313Y myostatin protein that reveals significantly decreased covalent dimerisation for C313Y myostatin accompanied by a loss of structural stability compared to wild type. The C313Y myostatin growth factor, processed from full length precursor protein, fails to inhibit C2C12 myoblast proliferation in contrast to wild type myostatin. Although structural modeling shows the substitution of tyrosine causes structural perturbation, biochemical analysis of additional disulphide mutants, C313A and C374A, indicates that an intact cystine-knot motif is a major determinant in myostatin growth factor stability and covalent dimerisation.</p> <p>Conclusions</p> <p>This research shows that the cystine-knot structure is important for myostatin dimerisation and stability, and that disruption of this structural motif perturbs myostatin signaling.</p

Structural Stability of Human Protein Tyrosine Phosphatase ρ Catalytic Domain: Effect of Point Mutations

Protein tyrosine phosphatase ρ (PTPρ) belongs to the classical receptor type IIB family of protein tyrosine phosphatase, the most frequently mutated tyrosine phosphatase in human cancer. There are evidences to suggest that PTPρ may act as a tumor suppressor gene and dysregulation of Tyr phosphorylation can be observed in diverse diseases, such as diabetes, immune deficiencies and cancer. PTPρ variants in the catalytic domain have been identified in cancer tissues. These natural variants are nonsynonymous single nucleotide polymorphisms, variations of a single nucleotide occurring in the coding region and leading to amino acid substitutions. In this study we investigated the effect of amino acid substitution on the structural stability and on the activity of the membrane-proximal catalytic domain of PTPρ. We expressed and purified as soluble recombinant proteins some of the mutants of the membrane-proximal catalytic domain of PTPρ identified in colorectal cancer and in the single nucleotide polymorphisms database. The mutants show a decreased thermal and thermodynamic stability and decreased activation energy relative to phosphatase activity, when compared to wild- type. All the variants show three-state equilibrium unfolding transitions similar to that of the wild- type, with the accumulation of a folding intermediate populated at ∼4.0 M urea

Proteogenomic review of the changes in primate apoC-I during evolution

Apolipoprotein C-I has evolved more rapidly than any of the other soluble apolipoproteins. During the course of primate evolution, the gene for this apolipoprotein was duplicated. Prompted by our observation that the two resulting genes encode two distinct forms of apoC-I in great apes, we have reviewed both the genomic and proteomic data to examine what changes have occurred during the course of primate evolution. We have found data showing that one of the duplicated genes, known to be a pseudogene in humans, was also a pseudogene in Denisovans and Neandertals. Using genomic and proteomic data for primates, we will provide in this review evidence that the duplication took place after the divergence of New World monkeys from the human lineage and that the formation of the pseudogene took place after the divergence of the bonobos and chimpanzees from the human lineage