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Using ancient protein kinases to unravel a modern cancer drug’s mechanism

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Science  20 Feb 2015:
Vol. 347, Issue 6224, pp. 882-886
DOI: 10.1126/science.aaa1823

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Evolution of dynamics affects function

The drug Gleevac inhibits Abl kinases and is used to treat multiple cancers. The closely related Src kinases also play a role in cancer but are not inhibited effectively by Gleevac. Nevertheless, Gleevac-bound structures of Src and Abl are nearly identical. Based on this structural information and protein sequence data, Wilson et al. reconstructed the common ancestor of Src and Abl. Mutations that affected conformational dynamics caused Gleevac affinity to be gained on the evolutionary trajectory toward Abl and lost on the trajectory toward Src.

Science, this issue p. 882

Abstract

Macromolecular function is rooted in energy landscapes, where sequence determines not a single structure but an ensemble of conformations. Hence, evolution modifies a protein’s function by altering its energy landscape. Here, we recreate the evolutionary pathway between two modern human oncogenes, Src and Abl, by reconstructing their common ancestors. Our evolutionary reconstruction combined with x-ray structures of the common ancestor and pre–steady-state kinetics reveals a detailed atomistic mechanism for selectivity of the successful cancer drug Gleevec. Gleevec affinity is gained during the evolutionary trajectory toward Abl and lost toward Src, primarily by shifting an induced-fit equilibrium that is also disrupted in the clinical T315I resistance mutation. This work reveals the mechanism of Gleevec specificity while offering insights into how energy landscapes evolve.

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