Association of UBP1 to ribonucleoprotein complexes is regulated by interaction with the trypanosome ortholog of the human multifunctional P32 protein.

Autor: Cassola, Alejandro, Romaniuk, María Albertina, Primrose, Debora, Cervini, Gabriela, D'Orso, Iván, Frasch, Alberto Carlos
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Zdroj: Molecular Microbiology; Sep2015, Vol. 97 Issue 6, p1079-1096, 18p, 3 Diagrams, 2 Graphs
Abstrakt: Regulation of gene expression in trypanosomatid parasitic protozoa is mainly achieved posttranscriptionally. RNA-binding proteins ( RBPs) associate to 3′ untranslated regions in m RNAs through dedicated domains such as the RNA recognition motif ( RRM). T rypanosoma cruzi UBP1 ( TcUBP1) is an RRM-type RBP involved in stabilization/degradation of m RNAs. TcUBP1 uses its RRM to associate with cytoplasmic m RNA and to m RNA granules under starvation stress. Here, we show that under starvation stress, TcUBP1 is tightly associated with condensed cytoplasmic m RNA granules. Conversely, under high nutrient/low density-growing conditions, TcUBP1 ribonucleoprotein ( RNP) complexes are lax and permeable to m RNA degradation and disassembly. After dissociating from m RNA, TcUBP1 can be phosphorylated only in unstressed parasites. We have identified TcP22, the ortholog of mammalian P32/ C1QBP, as an interactor of TcUBP1 RRM. Overexpression of TcP22 decreased the number of TcUBP1 granules in starved parasites in vivo. Endogenous TcUBP1 RNP complexes could be dissociated in vitro by addition of recombinant TcP22, a condition stimulating TcUBP1 phosphorylation. Biochemical and in silico analysis revealed that TcP22 interacts with the RNA-binding surface of TcUBP1 RRM. We propose a model for the decondensation of TcUBP1 RNP complexes in T . cruzi through direct interaction with TcP22 and phosphorylation. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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