Distinct photorespiratory reactions are preferentially catalyzed by glutamate:glyoxylate and serine:glyoxylate aminotransferases in rice

Zhisheng Zhang, Xingxue Mao, Juanying Ou, Nenghui Ye, Jianhua ZHANG, Xinxiang Peng*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

The metabolic function of glutamate:glyoxylate aminotransferase (GGAT) and serine:glyoxylate aminotransferase (SGAT) for photorespiration is still not exactly understood so far though it is mostly held that both enzymes may work in parallel in the reaction of glyoxylate to glycine during photorespiration of plants. Here, for the first time, we define the genes encoding GGAT and SGAT and report their biochemical and enzymatic properties in rice plants, in contrast to those from other plant species. Noticeably, GGAT exhibited approximately 18 fold higher catalytic efficiency (Kcat/Km) with glyoxylate and glutamate than SGAT with glyoxylate and serine, and additionally, rice leaves usually contain 3-4 times higher abundance of glutamate relative to serine, implicating that GGAT may preferentially utilize glyoxylate to form glycine over SGAT. When SGAT or GGAT activity was regulated by gene transformation or nitrogen deficiency, respectively, it was observed that the glycine content was positively related to GGAT activities, while both serine and glycine contents were negatively related to SGAT activities. The results suggest that GGAT preferentially catalyzes the conversion of glyoxylate into glycine while SGAT is mainly responsible for the transamination reaction of serine to hydroxypyruvate in the photorespiratory pathway of rice.

Original languageEnglish
Pages (from-to)110-117
Number of pages8
JournalJournal of Photochemistry and Photobiology B: Biology
Volume142
DOIs
Publication statusPublished - Jan 2015

Scopus Subject Areas

  • Radiation
  • Radiological and Ultrasound Technology
  • Biophysics
  • Radiology Nuclear Medicine and imaging

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