7pze
From Proteopedia
MademoiseLLE domain 2 of Rrm4 from Ustilago maydis
Structural highlights
FunctionRRM4_USTMA Key RNA-binding protein involved in the formation of polar-growing hyphae which is essential for infection by the plant pathogen (PubMed:15643068, PubMed:17105762, PubMed:19494833). During filamentation, assembles into particles that shuttle bidirectionally along microtubules to both poles (PubMed:17105762, PubMed:19494833, PubMed:30738139). The RRM4 transport particles are part of the endosomal mRNP transport that regulates polarity of the infectious hyphae by transporting distinct mRNAs encoding, for example, the ubiquitin fusion protein UBI1, the small G protein RHO3, or the septin CDC3, from the nucleus to cell poles (PubMed:17105762, PubMed:19494833, PubMed:22357951, PubMed:24355572, PubMed:25985087, PubMed:30738139). Recognizes a broad spectrum of cargo mRNAs and precisely binds at stop codons, which constitute landmark sites of translation, suggesting an intimate connection of mRNA transport and translation (PubMed:30552148). Binds also to the specific binding motif UAUG of cargo mRNAs via its third RRM (PubMed:30552148). Plus-end-directed KIN3, a kinesin-3 type motor, mediates anterograde transport of RRM4-containing mRNPs whereas split dynein DYM1-DYN2 functions in retrograde movement of mRNPs (PubMed:22357951).[1] [2] [3] [4] [5] [6] [7] [8] Publication Abstract from PubMedSpatiotemporal expression can be achieved by transport and translation of mRNAs at defined subcellular sites. An emerging mechanism mediating mRNA trafficking is microtubule-dependent co-transport on shuttling endosomes. Although progress has been made in identifying various components of the endosomal mRNA transport machinery, a mechanistic understanding of how these RNA-binding proteins are connected to endosomes is still lacking. Here, we demonstrate that a flexible MademoiseLLE (MLLE) domain platform within RNA-binding protein Rrm4 of Ustilago maydis is crucial for endosomal attachment. Our structure/function analysis uncovered three MLLE domains at the C-terminus of Rrm4 with a functionally defined hierarchy. MLLE3 recognises two PAM2-like sequences of the adaptor protein Upa1 and is essential for endosomal shuttling of Rrm4. MLLE1 and MLLE2 are most likely accessory domains exhibiting a variable binding mode for interaction with currently unknown partners. Thus, endosomal attachment of the mRNA transporter is orchestrated by a sophisticated MLLE domain binding platform. A MademoiseLLE domain binding platform links the key RNA transporter to endosomes.,Devan SK, Schott-Verdugo S, Muntjes K, Bismar L, Reiners J, Hachani E, Schmitt L, Hoppner A, Smits SH, Gohlke H, Feldbrugge M PLoS Genet. 2022 Jun 21;18(6):e1010269. doi: 10.1371/journal.pgen.1010269. , eCollection 2022 Jun. PMID:35727840[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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