Cytosolic Cysteine Synthase Switch Cysteine and Mimosine Production in Leucaena leucocephala

Harun-Ur-Rashid Md. Harun-Ur-Rashid, Hironori Iwasaki, Shahanaz Parveen, Shigeki Oogai, Masakazu Fukuta, Md Amzad Hossain, Toyoaki Anai, Hirosuke Oku

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13 Citations (Scopus)


In higher plants, multiple copies of the cysteine synthase gene are present for cysteine biosynthesis. Some of these genes also have the potential to produce various kinds of β-substitute alanine. In the present study, we cloned a 1275-bp cDNA for cytosolic O-acetylserine(thiol)lyase (cysteine synthase) (Cy-OASTL) from Leucaena leucocephala. The purified protein product showed a dual function of cysteine and mimosine synthesis. Kinetics studies showed pH optima of 7.5 and 8.0, while temperature optima of 40 and 35 °C, respectively, for cysteine and mimosine synthesis. The kinetic parameters such as apparent Km, kcat were determined for both cysteine and mimosine synthesis with substrates O-acetylserine (OAS) and Na2S or 3-hydroxy-4-pyridone (3H4P). From the in vitro results with the common substrate OAS, the apparent kcat for Cys production is over sixfold higher than mimosine synthesis and the apparent Km is 3.7 times lower, suggesting Cys synthesis is the favored pathway.

Original languageEnglish
Pages (from-to)613-632
Number of pages20
JournalApplied Biochemistry and Biotechnology
Issue number3
Publication statusPublished - Nov 1 2018
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Bioengineering
  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Molecular Biology


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