期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 294, 期 5, 页码 1529-1540出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.RA118.003995
关键词
RNA-binding protein; precursor tRNA (pre-tRNA); RNA processing; intracellular trafficking; protein domain; mass spectrometry (MS); RNA-protein interaction; La protein; Sjogren syndrome antigen B; SSB
资金
- Canadian Institutes of Health Research's Institute of Genetics
- Natural Sciences and Engineering Council of Canada [DG-544760]
- Collaborative Research and Development Program Grant [CRD-485321-15]
La proteins are RNA chaperones that perform various functions depending on distinct RNA-binding modes and their subcellular localization. In the nucleus, they help process UUU-3 ' OH-tailed nascent RNA polymerase III transcripts, such as pre-tRNAs, whereas in the cytoplasm they contribute to translation of poly(A)-tailed mRNAs. La accumulation in the nucleus and cytoplasm is controlled by several trafficking elements, including a canonical nuclear localization signal in the extreme C terminus and a nuclear retention element (NRE) in the RNA recognition motif 2 (RRM2) domain. Previous findings indicate that cytoplasmic export of La due to mutation of the NRE can be suppressed by mutations in RRM1, but the mechanism by which the RRM1 and RRM2 domains functionally cooperate is poorly understood. In this work, we use electromobility shift assays (EMSA) to show that mutations in the NRE and RRM1 affect binding of human La to pre-tRNAs but not UUU-3 ' OH or poly(A) sequences, and we present compensatory mutagenesis data supporting a direct interaction between the RRM1 and RRM2 domains. Moreover, we use collision-induced unfolding and time-resolved hydrogen-deuterium exchange MS analyses to study the conformational dynamics that occur when this interaction is intact or disrupted. Our results suggest that the intracellular distribution of La may be linked to its RNA-binding modes and provide the first evidence for a direct protein-protein interdomain interaction in La proteins.
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