A nuclear role for the DEAD-box protein Dbp5 in tRNA export

• Published in: eLife Vol. 8
• Main Authors: Lari, Azra, Arul Nambi Rajan, Arvind, Sandhu, Rima, Reiter, Taylor, Montpetit, Rachel, Young, Barry P, Loewen, Chris Jr, Montpetit, Ben
• Format: Journal Article
• Language: English
• Published: England eLife Science Publications, Ltd 27.08.2019; eLife Sciences Publications, Ltd; eLife Sciences Publications Ltd
• Subjects: Alleles; Amino acids; Biological Transport; Chromosomes and Gene Expression; DEAD-box protein; DEAD-box RNA Helicases - genetics; DEAD-box RNA Helicases - metabolism; DNA Mutational Analysis; Exports; Journalists; Mutagenesis, Site-Directed; Mutant Proteins - genetics; Mutant Proteins - metabolism; nuclear pore complex; Nucleocytoplasmic Transport Proteins - genetics; Nucleocytoplasmic Transport Proteins - metabolism; Physiological aspects; Point Mutation; Proteins; RNA; RNA export; RNA, Transfer - metabolism; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Transfer RNA; Canada; DEAD-box protein; nuclear pore complex; RNA export; gene expression; chromosomes; S. cerevisiae
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/eLife.48410

Dbp5 is an essential DEAD-box protein that mediates nuclear mRNP export. Dbp5 also shuttles between nuclear and cytoplasmic compartments with reported roles in transcription, ribosomal subunit export, and translation; however, the mechanism(s) by which nucleocytoplasmic transport occurs and how Dbp5 specifically contributes to each of these processes remains unclear. Towards understanding the functions and transport of Dbp5 in , alanine scanning mutagenesis was used to generate point mutants at all possible residues within a GFP-Dbp5 reporter. Characterization of the 456 viable mutants led to the identification of an N-terminal Xpo1-dependent nuclear export signal in Dbp5, in addition to other separation-of-function alleles, which together provide evidence that Dbp5 nuclear shuttling is not essential for mRNP export. Rather, disruptions in Dbp5 nucleocytoplasmic transport result in tRNA export defects, including changes in tRNA shuttling dynamics during recovery from nutrient stress.