Recognition of the let-7g miRNA precursor by human Lin28B

Mammalian homologs of lin28: Lin28 and Lin28B block the post-transcriptional processing of the let-7 family of miRNAs. We report that in vitro the terminal stem-loop region of the let-7g miRNA precursor (pre-let-7g) required to bind Lin28B is restricted to 24 nucleotides (nt) including the 3′ GGAG motif. Additionally, full length Lin28B is required for efficient binding to pre-let-7g and the stoichiometry of the complex is 1:1. Molecular dynamics (MD) simulations reveal the interactions of the pre-let-7g stem-loop and the GGAG motif in the stem region to the cold shock domain (CSD) and to the zinc knuckle domain (ZKD) of Lin28B, respectively.

► Full length Lin28B is required to efficiently bind pre-let-7g.
► Minimal length of pre-let-7g required to bind Lin28B is 24 nt.
► Stoichiometry of the Lin28B:pre-let-7g complex is 1:1.
► MD simulations reveal the interactions between Lin28B:pre-let-7g complex.