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Plant Physiol. 2015 Jun;168(2):752-64. doi: 10.1104/pp.15.00319. Epub 2015 Apr 28.

Algal dual-specificity tyrosine phosphorylation-regulated kinase, triacylglycerol accumulation regulator1, regulates accumulation of triacylglycerol in nitrogen or sulfur deficiency.

Author information

1
Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan (Ma.K., Y.S., H.S., T.Y., H.F.);Graduate School of Humanities and Sciences, Ochanomizu University, Tokyo 112-8610, Japan (A.A., Mi.K.);Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan (M.H.); andGraduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan (N.S.).
2
Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan (Ma.K., Y.S., H.S., T.Y., H.F.);Graduate School of Humanities and Sciences, Ochanomizu University, Tokyo 112-8610, Japan (A.A., Mi.K.);Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan (M.H.); andGraduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan (N.S.) fukuzawa@lif.kyoto-u.ac.jp.

Abstract

Although microalgae accumulate triacylglycerol (TAG) and starch in response to nutrient-deficient conditions, the regulatory mechanisms are poorly understood. We report here the identification and characterization of a kinase, triacylglycerol accumulation regulator1 (TAR1), that is a member of the yeast (Saccharomyces cerevisiae) Yet another kinase1 (Yak1) subfamily in the dual-specificity tyrosine phosphorylation-regulated kinase family in a green alga (Chlamydomonas reinhardtii). The kinase domain of TAR1 showed auto- and transphosphorylation activities. A TAR1-defective mutant, tar1-1, accumulated TAG to levels 0.5- and 0.1-fold of those of a wild-type strain in sulfur (S)- and nitrogen (N)-deficient conditions, respectively. In N-deficient conditions, tar1-1 showed more pronounced arrest of cell division than the wild type, had increased cell size and cell dry weight, and maintained chlorophyll and photosynthetic activity, which were not observed in S-deficient conditions. In N-deficient conditions, global changes in expression levels of N deficiency-responsive genes in N assimilation and tetrapyrrole metabolism were noted between tar1-1 and wild-type cells. These results indicated that TAR1 is a regulator of TAG accumulation in S- and N-deficient conditions, and it functions in cell growth and repression of photosynthesis in conditions of N deficiency.

PMID:
25922058
PMCID:
PMC4453788
DOI:
10.1104/pp.15.00319
[Indexed for MEDLINE]
Free PMC Article

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