Janosch Henning

European Molecular Biology Laboratory (EMBL)
Structural and Computational Biology Unit

E-mail: janosch.hennigembl.de

For more information and contact visit the Hennig lab.

Anne Ephrussi

European Molecular Biology Laboratory (EMBL)
Developmental Biology Unit

E-mail: ephrussiembl.de

For more information and contact visit the Ephrussi website.

RNA-binding proteins regulate every aspect of mRNA metabolism from its transcription to final degradation. In recent years a number of mRNA interactome capture studies have provided evidence for the existence of numerous previously unknown RNA-binding proteins which possess no classical RNA binding domains. To investigate the function of a number of selected putative RNA binders, we utilized nuclear magnetic resonance (NMR) in the first funding period to confirm the interaction in vitro. From this initial screen two Drosophila cytoskeletal proteins were selected for further structure-function analysis – End binding protein 1 (EB1) and an atypical isoform of Tropomyosin1 (aTm1).

EB1 is a master regulator of +tip microtubule dynamics and given its significance in cytoskeleton maintenance, it is of broad interest to uncover the functional significance of its interaction with RNA. We showed that EB1 binds RNA through its microtubule binding surface and have identified a number of transcripts to which it binds in the Drosophila oocyte. We would like to further investigate the functional significance of this interaction as well as the co-regulation of microtubule/RNA binding by posttranslational modifications such as phosphorylation.

The atypical Tm1 is a unique isoform of the actin-binding protein Tropomyosin1. aTm1 was recently identified as an adaptor for the binding of the motor protein Kinesin1 (Khc in Drosophila) to oskar mRNA. In the first funding period, we mapped the interaction regions of aTm1 and Khc and solved the crystal structure of a minimal aTm1-Khc complex. Further analysis of the binding of aTm1-Khc to RNA demonstrated that Khc binds RNA directly and that aTm1 plays a stabilizing role in this interaction, which distinguishes it from other classical cargo adaptors. To further investigate the mechanism of oskar-aTm1-Khc assembly we would like to identify the binding site of aTm1-Khc to oskar and reconstitute a ternary cargo-motor complex for further structure-function studies.  We believe that this will provide a better understanding of a cargo-adaptor-motor not only in the context of mRNA transport.

Dimitrova-Paternoga L, Jagtap PKA, Cyrklaff A, Vaishali, Sehr P, Perez K, Heber S, Löw C, Hennig J and Ephrussi A, Molecular basis of mRNA transport by a Kinesin-atypical Tropomyosin complex (2021). Genes and Development, 35(13-14):976-991 (doi: 10.1101/gad.348443.121).

Vaishali, Dimitrova-Paternoga L, Haubrich K, Sun M, Ephrussi A, Hennig J: Validation and classification of RNA binding proteins identified by mRNA interactome capture (2021). RNA, online ahead of print (doi: 10.1261/rna.078700.121).

Dimitrova-Paternoga L, Jagtap PKA, Chen PC, Hennig J, Integrative structural biology of protein-RNA complexes (2020). Structure, 28(1):6-28 (doi:10.1016/j.str.2019.11.017)