Albany 2015:Book of Abstracts
June 9-13 2015
©Adenine Press (2012)
Translational Regulation of Gene Expression: Lin28 and Roquin
RNA-binding proteins and non-coding RNAs co-operate in regulating gene expression by controlling mRNA homeostasis. Recently, we have studied structural aspects of RNA binding of two important human RNA-binding proteins, Lin28 and Roquin.
Lin28 regulates the maturation of let-7 microRNAs and binds to a large number of mRNAs (Graf et al., 2013). A Lin28-let-7 regulatory axis is involved in mediating cell differentiation or pluripotency, and LIN28 is over¬expressed in a number of cancers. We have analyzed the binding of Lin28 to pre-let-7 molecules by X-ray crystallography (Mayr et al., 2012) and find an RNA binding pattern of the protein's cold-shock domain (CSD) resembling that earlier observed in bacterial cold-shock proteins (Schindelin et al., 1992; Schindelin et al., 1993; Max et al., 2006; Max et al., 2007). Biochemical analyses and site-directed mutagenesis, combined with the structural data, provided evidence for an RNA binding model where the Lin28 CSD remodels the pre-let-7 structure in order to allow subsequent and sequence-specific binding of the Lin28 zinc-knuckle domain. Combined with other studies of the Lin28-let-7 interaction (Nam et al., 2011; Mayr & Heinemann, 2013) this work provides a structural framework for the function of Lin28 in translation-level gene regulation.
Roquin proteins recognize a conserved class of stem-loop RNA degradation motifs, leading to mRNA deadenylation. We have determined the crystal structure of the ROQ domain of human Roquin1/RC3H1 and revealed a mostly helical fold bearing a winged helix-turn-helix (wHTH) motif (Schuetz et al., 2014). Through biochemical and mutational analyses we demonstrate that the wHTH motif is involved in binding stem-loop mRNAs that carry constitutive decay elements. Being part of a recent deluge of Roquin structural studies (Schlundt et al., 2014; Tan et al., 2014; Srivastava et al., 2015) our work contributes to putting the biological function of Roquin proteins on a solid mechanistic basis.
Mayr, F., Schütz, A., Döge, N. & Heinemann, U. (2012) Nucleic Acids Res. 40, 7492-7506.
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Max, K.E.A., Zeeb, M., Bienert, R., Balbach, J. & Heinemann, U. (2006) J. Mol. Biol. 360, 702-714.
Max, K.E.A., Zeeb, M., Bienert, R., Balbach, J. & Heinemann, U. (2007) FEBS J. 274, 1265-1279.
Nam, Y., Chen, C., Gregory, R.I., Chou, J.J. & Kim, V.N. (2011) Cell 147, 1080-1091.
Mayr, F. & Heinemann, U. (2013) Int. J. Mol. Sci. 14, 16532-16553.
Schuetz, A., Murakawa, Y., Rosenbaum, E., Landthaler, M. & Heinemann, U. (2014) Nat. Commun. 5:5701.
Schlundt, A. et al. (2014) Nat. Struct. Mol. Biol. 21, 671-678.
Tan, D., Zhou, M., Kiledjian, M. & Tong, L. (2014) RNA. Nat. Struct. Mol. Biol. 21, 679-685.
Max-Delbrück Center for Molecular Medicine