高等植物におけるシステイン生合成の最終段階に関する分子的および代謝的研究   :   Molecular and Metabolic Studies on the Final Steps of Cysteine Biosynthetic Pathway in Higher Plants 

作成者 Kawashima, Cintia Goulart
キーワード等 cystine Biosynthetic Pathway, sulfur metabolism, serine acelyerarsferase
日本十進分類法 (NDC) 471.3
内容 学位:千大院医薬博甲第薬7号
抄録:Sulfur is an essential macronutrient in the plant life cycle. Inorganic sulfate is integrated in organic compounds via the cysteine biosynthesis. This pathway plays a central role in sulfur assimilation, and it involves several enzymatic reactions. Serine acetyltransferase (SATase) (EC, which catalyzes the formation of O-acetyl-L-serine (OAS) from L-ser and acetyl-CoA, links the serine metabolism to the cysteine biosynthesis. Subsequently, cysteine is formed by the condensation of sulfide and OAS, catalyzed by cysteine synthase [O-acetyl-L-serine(thiol) lyase (CSase); EC]. In Arabidopsis thaliana there are five genes putatively encoding SAT isoforms. Two of the five isoforms have not been characterized until now. Serat3; 1 and Serat3; 2 were characterized with respect to enzymatic properties, feedback inhibition and subcellular localization. Serat3; 2 was isolated by RACE-PCR, revealing a 329 amino acid polypeptide. The catalytical properties of the purified recombinant protein and the feedback inhibition were determined. Serat3; 1 was not inhibited by L-cysteine, while Serat3; 2 was feedback inhibition-sensitive isozyme. These two isoforms showed low affinity to their substrates and low enzyme activity compared with the other three characterized SATases. The analysis revealed that Serat3; 1 and Serat3; 2 are localized in cytosol. In 5-week-old leaves, Serat3; 2 was localized in chloroplasts. Expression of Serine acetyltransferase (SATase) gene family isoforms from Arabidopsis thaliana was investigated under plant development and in response to sulfur deficient condition and to response to treatment with the heavy metal cadmium (Cd). Northern analysis of SATases revelaled tissue-specific expression patterns for each isogene. By real-time quantitative PCR, expression pattern analysis of the SATase isoforms during plant development was performed.

作成日付 2004
コンテンツの種類 博士論文 Doctoral Thesis
DCMI資源タイプ text
ファイル形式 application/pdf
言語 日本語

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