Tags

Type your tag names separated by a space and hit enter

Biochemical and Chemical Biology Study of Rice OsTAR1 Revealed that Tryptophan Aminotransferase is Involved in Auxin Biosynthesis: Identification of a Potent OsTAR1 Inhibitor, Pyruvamine2031.
Plant Cell Physiol. 2017 Mar 01; 58(3):598-606.PC

Abstract

IAA, a major form of auxin, is biosynthesized from l-tryptophan via the indole-3-pyruvic acid (IPyA) pathway in Arabidopsis. Tryptophan aminotransferases (TAA1/TARs) catalyze the first step from l-tryptophan to IPyA. In rice, the importance of TAA/TARs or YUC homologs in auxin biosynthesis has been suggested, but the enzymatic activities and involvement of the intermediate IPyA in auxin biosynthesis remain elusive. In this study, we obtained biochemical evidence that the rice tryptophan aminotransferase OsTAR1 converts l-tryptophan to IPyA, and has a Km of 82.02 µM and a Vmax of 10.92 µM min-1 m-1, comparable with those in Arabidopsis. Next, we screened for an effective inhibitor of OsTAR1 from our previously reported inhibitor library for TAA1/TARs, designated pyruvamine (PVM). Differing from previous observations in Arabidopsis, hydroxy-type PVMs, e.g. PVM2031 (previous name KOK2031), had stronger inhibitory effects in rice than the methoxy-type. PVM2031 inhibited recombinant OsTAR1 in vitro. The Ki of PVM2031 was 276 nM. PVM2031 treatment of rice seedlings resulted in morphological changes in vivo, such as reduced lateral root density. Exogenous IAA rescued this growth inhibition, suggesting that the inhibitory effect is auxin specific. Furthermore, rice roots showed reduced IAA levels concomitant with reduced levels of IPyA in the presence of the inhibitors, suggesting that the IPyA pathway is an auxin biosynthesis pathway in rice. Since PVM2031 showed stronger inhibitory effects on rice auxin biosynthesis than known tryptophan aminotransferase inhibitors, we propose that the hydroxy-type PVM2031 is an effective tool for biochemical analysis of the function of auxin biosynthesis in rice roots.

Authors+Show Affiliations

Yokohama City University, Kihara Institute for Biological Research, Maiokacho 641-12, Totsuka, Yokohama, Kanagawa, 244-0813 Japan.Yokohama City University, Kihara Institute for Biological Research, Maiokacho 641-12, Totsuka, Yokohama, Kanagawa, 244-0813 Japan.Yokohama City University, Kihara Institute for Biological Research, Maiokacho 641-12, Totsuka, Yokohama, Kanagawa, 244-0813 Japan.Yokohama City University, Kihara Institute for Biological Research, Maiokacho 641-12, Totsuka, Yokohama, Kanagawa, 244-0813 Japan.Yokohama City University, Kihara Institute for Biological Research, Maiokacho 641-12, Totsuka, Yokohama, Kanagawa, 244-0813 Japan.Yokohama City University, Kihara Institute for Biological Research, Maiokacho 641-12, Totsuka, Yokohama, Kanagawa, 244-0813 Japan.Yokohama City University, Kihara Institute for Biological Research, Maiokacho 641-12, Totsuka, Yokohama, Kanagawa, 244-0813 Japan. Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba, 278-8510 Japan.National Agriculture and Food Research Organization (NARO), Western Region Agricultural Research Center (WARC), Senyu, Zentsuji, Kagawa, 765-8508 Japan.Yokohama City University, Kihara Institute for Biological Research, Maiokacho 641-12, Totsuka, Yokohama, Kanagawa, 244-0813 Japan.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

28138057

Citation

Kakei, Yusuke, et al. "Biochemical and Chemical Biology Study of Rice OsTAR1 Revealed That Tryptophan Aminotransferase Is Involved in Auxin Biosynthesis: Identification of a Potent OsTAR1 Inhibitor, Pyruvamine2031." Plant & Cell Physiology, vol. 58, no. 3, 2017, pp. 598-606.
Kakei Y, Nakamura A, Yamamoto M, et al. Biochemical and Chemical Biology Study of Rice OsTAR1 Revealed that Tryptophan Aminotransferase is Involved in Auxin Biosynthesis: Identification of a Potent OsTAR1 Inhibitor, Pyruvamine2031. Plant Cell Physiol. 2017;58(3):598-606.
Kakei, Y., Nakamura, A., Yamamoto, M., Ishida, Y., Yamazaki, C., Sato, A., Narukawa-Nara, M., Soeno, K., & Shimada, Y. (2017). Biochemical and Chemical Biology Study of Rice OsTAR1 Revealed that Tryptophan Aminotransferase is Involved in Auxin Biosynthesis: Identification of a Potent OsTAR1 Inhibitor, Pyruvamine2031. Plant & Cell Physiology, 58(3), 598-606. https://doi.org/10.1093/pcp/pcx007
Kakei Y, et al. Biochemical and Chemical Biology Study of Rice OsTAR1 Revealed That Tryptophan Aminotransferase Is Involved in Auxin Biosynthesis: Identification of a Potent OsTAR1 Inhibitor, Pyruvamine2031. Plant Cell Physiol. 2017 Mar 1;58(3):598-606. PubMed PMID: 28138057.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Biochemical and Chemical Biology Study of Rice OsTAR1 Revealed that Tryptophan Aminotransferase is Involved in Auxin Biosynthesis: Identification of a Potent OsTAR1 Inhibitor, Pyruvamine2031. AU - Kakei,Yusuke, AU - Nakamura,Ayako, AU - Yamamoto,Mitsuhiro, AU - Ishida,Yosuke, AU - Yamazaki,Chiaki, AU - Sato,Akiko, AU - Narukawa-Nara,Megumi, AU - Soeno,Kazuo, AU - Shimada,Yukihisa, PY - 2016/09/13/received PY - 2017/01/11/accepted PY - 2017/2/1/pubmed PY - 2018/4/3/medline PY - 2017/2/1/entrez KW - Auxin biosynthesis inhibitor KW - Chemical biology KW - Oryza sativa KW - TAA1/TARs SP - 598 EP - 606 JF - Plant & cell physiology JO - Plant Cell Physiol VL - 58 IS - 3 N2 - IAA, a major form of auxin, is biosynthesized from l-tryptophan via the indole-3-pyruvic acid (IPyA) pathway in Arabidopsis. Tryptophan aminotransferases (TAA1/TARs) catalyze the first step from l-tryptophan to IPyA. In rice, the importance of TAA/TARs or YUC homologs in auxin biosynthesis has been suggested, but the enzymatic activities and involvement of the intermediate IPyA in auxin biosynthesis remain elusive. In this study, we obtained biochemical evidence that the rice tryptophan aminotransferase OsTAR1 converts l-tryptophan to IPyA, and has a Km of 82.02 µM and a Vmax of 10.92 µM min-1 m-1, comparable with those in Arabidopsis. Next, we screened for an effective inhibitor of OsTAR1 from our previously reported inhibitor library for TAA1/TARs, designated pyruvamine (PVM). Differing from previous observations in Arabidopsis, hydroxy-type PVMs, e.g. PVM2031 (previous name KOK2031), had stronger inhibitory effects in rice than the methoxy-type. PVM2031 inhibited recombinant OsTAR1 in vitro. The Ki of PVM2031 was 276 nM. PVM2031 treatment of rice seedlings resulted in morphological changes in vivo, such as reduced lateral root density. Exogenous IAA rescued this growth inhibition, suggesting that the inhibitory effect is auxin specific. Furthermore, rice roots showed reduced IAA levels concomitant with reduced levels of IPyA in the presence of the inhibitors, suggesting that the IPyA pathway is an auxin biosynthesis pathway in rice. Since PVM2031 showed stronger inhibitory effects on rice auxin biosynthesis than known tryptophan aminotransferase inhibitors, we propose that the hydroxy-type PVM2031 is an effective tool for biochemical analysis of the function of auxin biosynthesis in rice roots. SN - 1471-9053 UR - https://www.unboundmedicine.com/medline/citation/28138057/Biochemical_and_Chemical_Biology_Study_of_Rice_OsTAR1_Revealed_that_Tryptophan_Aminotransferase_is_Involved_in_Auxin_Biosynthesis:_Identification_of_a_Potent_OsTAR1_Inhibitor_Pyruvamine2031_ L2 - https://academic.oup.com/pcp/article-lookup/doi/10.1093/pcp/pcx007 DB - PRIME DP - Unbound Medicine ER -