title: ANKYRIN REPEAT-CONTAINING PROTEIN 2A is an essential molecular chaperone for peroxisomal membrane-bound ASCORBATE PEROXIDASE3 in Arabidopsis.
abstract: Arabidopsis thaliana ANKYRIN REPEAT-CONTAINING PROTEIN 2A (AKR2A) interacts with peroxisomal membrane-bound ASCORBATE PEROXIDASE3 (APX3). This interaction involves the C-terminal sequence of APX3 (i.e., a transmembrane domain plus a few basic amino acid residues). The specificity of the AKR2A-APX3 interaction suggests that AKR2A may function as a molecular chaperone for APX3 because binding of AKR2A to the transmembrane domain can prevent APX3 from forming aggregates after translation. Analysis of three akr2a mutants indicates that these mutant plants have reduced steady state levels of APX3. Reduced expression of AKR2A using RNA interference also leads to reduced steady state levels of APX3 and reduced targeting of APX3 to peroxisomes in plant cells. Since AKR2A also binds specifically to the chloroplast OUTER ENVELOPE PROTEIN7 (OEP7) and is required for the biogenesis of OEP7, AKR2A may serve as a molecular chaperone for OEP7 as well. The pleiotropic phenotype of akr2a mutants indicates that AKR2A plays many important roles in plant cellular metabolism and is essential for plant growth and development.
authors.affiliation: Department of Biological Sciences, Texas Tech University, Lubbock, Texas 79409, USA.
authors.forename: Guoxin
authors.initials: G
authors.lastname: Shen
authors.forename: Sundaram
authors.initials: S
authors.lastname: Kuppu
authors.forename: Sujatha
authors.initials: S
authors.lastname: Venkataramani
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Juqiang
authors.initials: J
authors.lastname: Yan
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Qiu
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
mesh_terms: D017089:Ankyrin Repeat; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D060387:Ascorbate Peroxidases; D018506:Gene Expression Regulation, Plant; D008565:Membrane Proteins; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D010544:Peroxidases / Q000235:genetics / Q000378:metabolism*; D020675:Peroxisomes / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D025941:Protein Interaction Mapping; D034622:RNA Interference
chemical_list: C451699:AKR2 protein, Arabidopsis; D029681:Arabidopsis Proteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; D010544:Peroxidases; C555294:APX3 protein, Arabidopsis; D060387:Ascorbate Peroxidases