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An RNA ‐binding atypical tropomyosin recruits kinesin‐1 dynamically to oskar mRNP s
Author(s) -
Gáspár Imre,
Sysoev Vasiliy,
Komissarov Artem,
Ephrussi Anne
Publication year - 2016
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.201696038
Subject(s) - oskar , kinesin , dynein , biology , microbiology and biotechnology , dynactin , motor protein , oocyte , microtubule , ribonucleoprotein , molecular motor , untranslated region , rna , genetics , embryo , gene
Localization and local translation of oskar mRNA at the posterior pole of the Drosophila oocyte directs abdominal patterning and germline formation in the embryo. The process requires recruitment and precise regulation of motor proteins to form transport‐competent mRNP s. We show that the posterior‐targeting kinesin‐1 is loaded upon nuclear export of oskar mRNP s, prior to their dynein‐dependent transport from the nurse cells into the oocyte. We demonstrate that kinesin‐1 recruitment requires the Dm Tropomyosin1‐I/C isoform, an atypical RNA ‐binding tropomyosin that binds directly to dimerizing oskar 3′ UTR s. Finally, we show that a small but dynamically changing subset of oskar mRNP s gets loaded with inactive kinesin‐1 and that the motor is activated during mid‐oogenesis by the functionalized spliced oskar RNA localization element. This inefficient, dynamic recruitment of Khc decoupled from cargo‐dependent motor activation constitutes an optimized, coordinated mechanism of mRNP transport, by minimizing interference with other cargo‐transport processes and between the cargo‐associated dynein and kinesin‐1.