title: Partial dispensability of Djp1's J domain in peroxisomal protein import in Saccharomyces cerevisiae results from genetic redundancy with another class II J protein, Caj1.
abstract: J proteins are obligate co-chaperones of Hsp70s. Via their signature J domain, all J proteins interact with their partner Hsp70s and stimulate their weak ATPase activity, which is vital for Hsp70 functions. The dependency of J proteins on their J domain is such that mutations in critical amino acids in the J domain often results into a null phenotype for a particular J protein. Here, we show that the J domain of Djp1, a cytosolic J protein important for peroxisomal protein import in Saccharomyces cerevisiae, is partially dispensable. A complete deletion of Djp1 J domain resulted into only partial loss in peroxisomal protein import function. Instead, the C-terminal domain of Djp1 was found to be essential for proper localization of the peroxisomal targeted GFP-PTS1. Furthermore, we show that Caj1, another cytosolic J protein, also has some role in peroxisomal protein import. Caj1 was found to be partially redundant with Djp1 as cells lacking both Djp1 and Caj1 resulted into a much more severe defect in GFP-PTS1 localization. Based on these results, we propose that dispensability of J domains could be attributed to genetic redundancy between different J proteins sharing common structural topology and cellular localization.
authors.affiliation: Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, Madhya Pradesh, India.
authors.forename: Neha
authors.initials: N
authors.lastname: Dobriyal
authors.affiliation: Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, Madhya Pradesh, India.
authors.forename: Prerna
authors.initials: P
authors.lastname: Tripathi
authors.affiliation: Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, Madhya Pradesh, India.|Department of Biology, Boston University, Boston, MA, 02215, USA.
authors.forename: Susrita
authors.initials: S
authors.lastname: Sarkar
authors.affiliation: Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, Madhya Pradesh, India.
authors.forename: Yogesh
authors.initials: Y
authors.lastname: Tak
authors.affiliation: Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, Madhya Pradesh, India.
authors.forename: Amit K
authors.initials: AK
authors.lastname: Verma
authors.affiliation: Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, Madhya Pradesh, India. sahi@iiserb.ac.in.
authors.forename: Chandan
authors.identifier: 0000-0002-4821-9736
authors.initials: C
authors.lastname: Sahi
mesh_terms: D002148:Calmodulin-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D050956:HSP40 Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020648:Peptide Elongation Factor 1 / Q000235:genetics; D000074404:Peroxisomal Targeting Signals / Q000235:genetics; D020675:Peroxisomes / Q000378:metabolism*; D010641:Phenotype; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D000072417:Protein Domains; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: C088621:CAJ1 protein, S cerevisiae; D002148:Calmodulin-Binding Proteins; C584545:Djp1 protein, S cerevisiae; D050956:HSP40 Heat-Shock Proteins; D018832:Molecular Chaperones; D020648:Peptide Elongation Factor 1; D000074404:Peroxisomal Targeting Signals; D029701:Saccharomyces cerevisiae Proteins; C410826:TEF1 protein, S cerevisiae; D049452:Green Fluorescent Proteins
keywords: Caj1; Djp1; J domain; J proteins; Peroxisome; Yeast