title: Overexpression of the PP2A-C5 gene confers increased salt tolerance in Arabidopsis thaliana.
abstract: Protein phosphatase 2A (PP2A) was shown to play important roles in biotic and abiotic stress signaling pathways in plants. PP2A is made of 3 subunits: a scaffolding subunit A, a regulatory subunit B, and a catalytic subunit C. It is believed that the B subunit recognizes specific substrates and the C subunit directly acts on the selected substrates, whereas the A subunit brings a B subunit and a C subunit together to form a specific PP2A holoenzyme. Because there are multiple isoforms for each PP2A subunit, there could be hundreds of novel PP2A holoenzymes in plants. For an example, there are 3 A subunits, 17 B subunits, and 5 C subunits in Arabidopsis, which could form 255 different PP2A holoenzymes. Understanding the roles of these PP2A holoenzymes in various signaling pathways is a challenging task. In a recent study,1we discovered that PP2A-C5, the catalytic subunit 5 of PP2A, plays an important role in salt tolerance in Arabidopsis. We found that a knockout mutant of PP2A-C5 (i.e. pp2a-c5-1) was very sensitive to salt treatments, whereas PP2A-C5-overexpressing plants were more tolerant to salt stresses. Genetic analyses between pp2a-c5-1 and Salt-Overly-Sensitive (SOS) mutants indicated that PP2A-C5 does not function in the same pathway as SOS genes. Using yeast 2-hybrid analysis, we found that PP2A-C5 interacts with several vacuolar membrane bound chloride channel proteins. We hypothesize that these vacuolar chloride channel proteins might be PP2A-C5's substrates in vivo, and the action of PP2A-C5 on these channel proteins could increase or activate their activities, thereby result in accumulation of the chloride and sodium contents in vacuoles, leading to increased salt tolerance in plants.
authors.affiliation: a Department of Biological Sciences , Texas Tech University , Lubbock , TX , USA.
authors.forename: Rongbin
authors.initials: R
authors.lastname: Hu
authors.affiliation: a Department of Biological Sciences , Texas Tech University , Lubbock , TX , USA.
authors.forename: Yinfeng
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: b Zhejiang Academy of Agricultural Sciences , Hangzhou, Zhejiang Province , China.
authors.forename: Guoxin
authors.initials: G
authors.lastname: Shen
authors.affiliation: a Department of Biological Sciences , Texas Tech University , Lubbock , TX , USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D008962:Models, Theoretical; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D054648:Protein Phosphatase 2 / Q000235:genetics / Q000378:metabolism*; D055049:Salt Tolerance / Q000235:genetics; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D029681:Arabidopsis Proteins; D012965:Sodium Chloride; D054648:Protein Phosphatase 2
keywords: Chloride channel protein; protein phosphatase 2A; salt stress; signaling