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bioRxiv · 10.1101/154823

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

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

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.

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Le, V. Q., Iacob, R. E., Tian, Y., McConaughy, W., Su, Y., Zhao, B., Engen, J. R., Pirruccello-Straub, M., Springer, T. A.. 2017-06-23. Tolloid cleavage activates latent GDF8 by priming the pro-complex for dissociation. https://doi.org/10.1101/154823

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