PMID: 30652968

Authors:

Bhat VD, McCann KL, Wang Y, Fonseca DR, Shukla T, Alexander JC, Qiu C, Wickens M, Lo TW, Tanaka Hall TM, Campbell ZT

Title:

Engineering a conserved RNA regulatory protein repurposes its biological function in vivo.

Journal:

Elife. 2019 Jan 17;8. pii: 43788. doi: 10.7554/eLife.43788.

Abstract:

PUF (PUmilio/FBF) RNA-binding proteins recognize distinct elements. In C. elegans, PUF-8 binds to an 8-nt motif and restricts proliferation in the germline. Conversely, FBF-2 recognizes a 9-nt element and promotes mitosis. To understand how motif divergence relates to biological function, we first determined a crystal structure of PUF-8. Comparison of this structure to that of FBF-2 revealed a major difference in a central repeat. We devised a modified yeast 3-hybrid screen to identify mutations that confer recognition of an 8-nt element to FBF-2. We identified several such mutants and validated structurally and biochemically their binding to 8-nt RNA elements. Using genome engineering, we generated a mutant animal with a substitution in FBF-2 that confers preferential binding to the PUF-8 element. The mutant largely rescued overproliferation in animals that spontaneously generate tumors in the absence of puf-8. This work highlights the critical role of motif length in the specification of biological function.