Algal dual-specificity tyrosine phosphorylation-regulated kinase, triacylglycerol accumulation regulator1, regulates accumulation of triacylglycerol in nitrogen or sulfur deficiency.
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.
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.).
Masataka
M
Kajikawa
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.).
Yuri
Y
Sawaragi
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.).
Haruka
H
Shinkawa
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.).
Takashi
T
Yamano
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.).
Akira
A
Ando
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.).
Misako
M
Kato
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.).
Masafumi
M
Hirono
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.).
Naoki
N
Sato
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.
Hideya
http://orcid.org/0000-0003-0963-5662
H
Fukuzawa
D016825:Chlamydomonas reinhardtii / Q000201:enzymology* / Q000235:genetics; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D066292:Lipid Droplets / Q000187:drug effects / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009584:Nitrogen / Q000172:deficiency* / Q000494:pharmacology; D010641:Phenotype; D010766:Phosphorylation / Q000187:drug effects; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D013213:Starch / Q000378:metabolism; D013455:Sulfur / Q000172:deficiency* / Q000494:pharmacology; D014280:Triglycerides / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*
D010940:Plant Proteins; D014280:Triglycerides; D014443:Tyrosine; D013455:Sulfur; D013213:Starch; D009584:Nitrogen