PMID: 28297670

Authors:

Wang L, Nam Y, Lee AK, Yu C, Roth K, Chen C, Ransey EM, Sliz P

Title:

LIN28 Zinc Knuckle Domain Is Required and Sufficient to Induce let-7 Oligouridylation.

Journal:

Cell Rep. 2017 Mar 14;18(11):2664-2675. doi: 10.1016/j.celrep.2017.02.044.

Abstract:

LIN28 is an RNA binding protein that plays crucial roles in pluripotency, glucose metabolism, tissue regeneration, and tumorigenesis. LIN28 binds to the let-7 primary and precursor microRNAs through bipartite recognition and induces degradation of let-7 precursors (pre-let-7) by promoting oligouridylation by terminal uridylyltransferases (TUTases). Here, we report that the zinc knuckle domain (ZKD) of mouse LIN28 recruits TUT4 to initiate the oligouridylation of let-7 precursors. Our crystal structure of human LIN28 in complex with a fragment of pre-let-7f-1 determined to 2.0 A resolution shows that the interaction between ZKD and RNA is constrained to a small cavity with a high druggability score. We demonstrate that the specific interaction between ZKD and pre-let-7 is necessary and sufficient to induce oligouridylation by recruiting the N-terminal fragment of TUT4 (NTUT4) and the formation of a stable ZKD:NTUT4:pre-let-7 ternary complex is crucial for the acquired processivity of TUT4.