Athb-12, a homeobox-leucine zipper domain protein from Arabidopsis thaliana, increases salt tolerance in yeast by regulating sodium exclusion.

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. Copyright 2004 Elsevier Inc.

Citation

Dongjin Shin, Yoon Duck Koo, Jiyoung Lee, Hyo-Jung Lee, Dongwon Baek, Sukchan Lee, Choong-Ill Cheon, Sang-Soo Kwak, Sang Yeol Lee, Dae-Jin Yun. Athb-12, a homeobox-leucine zipper domain protein from Arabidopsis thaliana, increases salt tolerance in yeast by regulating sodium exclusion. Biochemical and biophysical research communications. 2004 Oct 15;323(2):534-40

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PMID: 15369784

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