Tolloid cleavage activates latent GDF8 by priming the pro-complex for dissociation

5 years ago

Tolloid cleavage activates latent GDF8 by priming the pro-complex for dissociation

B., Zhao, Le, T. A., M., Pirruccello-Straub, Engen, Su, Iacob, J. R., Tian, Springer, Y., W., R. E., McConaughy, V. Q.

Growth differentiation factor 8 (GDF8)/Myostatin is a latent TGF-{beta} family member that potently inhibits skeletal muscle growth. Here, we compared the conformation and dynamics of precursor, latent, and Tolloid-cleaved GDF8 pro-complexes to understand structural mechanisms underlying latency and activation of GDF8. Negative stain electron microscopy (EM) of precursor and latent pro-complexes reveals a V-shaped conformation that is unaltered by furin cleavage and sharply contrasts with the ring-like, cross-armed conformation of latent TGF-{beta}1. Surprisingly, Tolloid-cleaved GDF8 does not immediately dissociate, but in EM exhibits structural heterogeneity consistent with partial dissociation. Hydrogen-deuterium exchange was not affected by furin cleavage. In contrast, Tolloid cleavage, in the absence of prodomain-growth factor dissociation, increased exchange in regions that correspond in pro-TGF-{beta}1 to the 1-helix, latency lasso, and {beta}1 strand in the prodomain and to the {beta}6'-7' strands in the growth factor. Thus, these regions are important in maintaining GDF8 latency. Our results show that Tolloid cleavage activates latent GDF8 by destabilizing specific prodomain-growth factor interfaces and primes the growth factor for release from the prodomain.

Publisher URL: http://biorxiv.org/cgi/content/short/154823v1

DOI: 10.1101/154823