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- Title
Molecular characterization of cytosolic cysteine synthase in <italic>Mimosa pudica</italic>.
- Authors
Rashid, Md. Harun-Ur-; Iwasaki, Hironori; Oogai, Shigeki; Fukuta, Masakazu; Parveen, Shahanaz; Hossain, Md. Amzad; Anai, Toyoaki; Oku, Hirosuke
- Abstract
In the cysteine and mimosine biosynthesis process, <italic>O</italic>-acetyl-l-serine (OAS) is the common substrate. In the presence of <italic>O</italic>-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 <italic>M. pudica</italic> 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−1 values were 159 ± 21 µM, 33.56 s−1, and 211.07 mM−1s−1 for OAS and 252 ± 25 µM, 32.99 s−1, and 130.91 mM−1s−1 for Na2S according to the <italic>in vitro</italic> Cys assay. The Cy-OASTL of <italic>Mimosa pudica</italic> is specific to Cys production, although it contains sensory roles in sulfur assimilation and the reduction network in the intracellular environment of <italic>M. pudica</italic>.
- Subjects
SENSITIVE plant; CYSTEINE synthase; HYDROXYPYRIDONES; MIMOSINE; NUCLEOTIDES
- Publication
Journal of Plant Research, 2018, Vol 131, Issue 2, p319
- ISSN
0918-9440
- Publication type
Article
- DOI
10.1007/s10265-017-0986-5