RT Journal Article
SR Electronic
T1 Tolloid cleavage activates latent GDF8 by priming the pro-complex for dissociation
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 154823
DO 10.1101/154823
A1 Viet Q. Le
A1 Roxana E. Iacob
A1 Yuan Tian
A1 William McConaughy
A1 Yang Su
A1 Bo Zhao
A1 John R. Engen
A1 Michelle Pirruccello-Straub
A1 Timothy A. Springer
YR 2017
UL http://biorxiv.org/content/early/2017/06/23/154823.abstract
AB Growth differentiation factor 8 (GDF8)/Myostatin is a latent TGF-β 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-β1. 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-β1 to the α1-helix, latency lasso, and β1 strand in the prodomain and to the β6’– β7’ 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.