title: Athb-12, a homeobox-leucine zipper domain protein from Arabidopsis thaliana, increases salt tolerance in yeast by regulating sodium exclusion.
abstract: An Arabidopsis cDNA clone that encodes Athb-12, a homeobox-leucine zipper domain protein (HD-Zip), was isolated by functional complementation of the NaCl-sensitive phenotype of a calcineurin (CaN)-deficient yeast mutant (cnbDelta, regulatory subunit null). CaN, a Ca2+/calmodulin-dependent protein phosphatase, regulates Na+ ion homeostasis in yeast. Expression of Athb-12 increased NaCl tolerance but not osmotic stress tolerance of these cnbDelta cells. Furthermore, expression of two other HD-Zip from Arabidopsis, Athb-1 and -7, did not suppress NaCl sensitivity of cnbDelta cells. These results suggest that Athb-12 specifically functions in Na+ ion homeostasis in yeast. Consistent with these observations, expression of Athb-12 in yeast turned on transcription of the NaCl stress-inducible PMR2A, which encodes a Na+/Li+ translocating P-type ATPase, and decreased Na+ levels in yeast cells. To investigate the biological function of Athb-12 in Arabidopsis, we performed Northern blot analysis. Expression of Athb-12 was dramatically induced by NaCl and ABA treatments, but not by KCl. In vivo targeting experiments using a green fluorescent protein reporter indicated that Athb-12 was localized to the nucleus. These results suggest that Athb-12 is a putative transcription factor that may be involved in NaCl stress responses in plants.
authors.affiliation: Division of Applied Life Science (BK21 Program) and Environmental Biotechnology National Core Research Center, Graduate School of Gyeongsang National University, Jinju 660-701, Republic of Korea.
authors.forename: Dongjin
authors.initials: D
authors.lastname: Shin
authors.forename: Yoon Duck
authors.initials: YD
authors.lastname: Koo
authors.forename: Jiyoung
authors.initials: J
authors.lastname: Lee
authors.forename: Hyo-Jung
authors.initials: HJ
authors.lastname: Lee
authors.forename: Dongwon
authors.initials: D
authors.lastname: Baek
authors.forename: Sukchan
authors.initials: S
authors.lastname: Lee
authors.forename: Choong-Ill
authors.initials: CI
authors.lastname: Cheon
authors.forename: Sang-Soo
authors.initials: SS
authors.lastname: Kwak
authors.forename: Sang Yeol
authors.initials: SY
authors.lastname: Lee
authors.forename: Dae-Jin
authors.initials: DJ
authors.lastname: Yun
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004361:Drug Tolerance / Q000502:physiology; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D016350:Leucine Zippers / Q000235:genetics; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D012964:Sodium / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology*; D014018:Tissue Distribution; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014882:Water-Electrolyte Balance / Q000187:drug effects / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors; C112532:atHB-12 protein, Arabidopsis; D012965:Sodium Chloride; D012964:Sodium