Molecular characterization of cytosolic cysteine synthase in Mimosa pudica

Abstract

In the cysteine and mimosine biosynthesis process, O-acetyl-L-serine (OAS) is the common substrate. In the presence of O-acetylserine (thiol) lyase (OASTL, cysteine synthase) the reaction of OAS with sulfide produces cysteine, while with 3-hydroxy-4-pyridone (3H4P) produces mimosine. The enzyme OASTL can either catalyze Cys synthesis or both Cys and mimosine. A cDNA for cytosolic OASTL was cloned from M. pudica for the first time containing 1,410 bp nucleotides. The purified protein product from overexpressed bacterial cells produced Cys only, but not mimosine, indicating it is Cys specific. Kinetic studies revealed that pH and temperature optima for Cys production were 6.5 and 50 °C, respectively. The measured Km, Kcat, and Kcat Km values were 159 ± 21 µM, 33.56 s, and 211.07 mMs for OAS and 252 ± 25 µM, 32.99 s, and 130.91 mMs for NaS according to the in vitro Cys assay. The Cy-OASTL of Mimosa pudica is specific to Cys production, although it contains sensory roles in sulfur assimilation and the reduction network in the intracellular environment of M. pudica.

Critical Sites of Serine Acetyltransferase in Lathyrus sativus L. Affecting Its Enzymatic Activities

“…In legumes, biosynthesis of several secondary metabolites including β-cyanoalanine in Vicia sativa (common vetch), β-ODAP in Lathyrus species, and mimosine in Mimosa pudica is related to sulfur metabolism. ,, Generally, SAT that catalyzes the production of OAS from serine and acetyl-CoA is the rate-limiting enzyme in sulfur metabolism for its lower expression level . Three LsSATs were found in L.…”

…Fell Upas Sits, the Hydra-Tree of Death †, or the Phytotoxicity of Trees

“…However, it turned out that cytosolic OAS-TL is specific for only cysteine synthesis and does not catalyze mimosine formation. The Mimosa pudica Mill enzyme has similar properties: the cloned cytosolic OASTL 1275 bp long cDNA expressed in E. coli , but enzyme produced cystein only [270]. Harun-Ur-Rashid et al [271] was the first to obtain the enzyme involved in the synthesis of mimosine.…”