Cysteine biosynthesis in the Archaea: Methanosarcina thermophila utilizes O-acetylserine sulfhydrylase

Authors

  • Birthe Borup,

    1. Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA
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  • James G. Ferry

    Corresponding author
    1. Department of Biochemistry and Molecular Biology, 205 South Frear Laboratory, Pennsylvania State University, University Park, PA 16802, USA
      *Corresponding author. Tel.: +1 (814) 863-5721; Fax: +1 (814) 863-6217, E-mail address: jgf3@psu.edu
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*Corresponding author. Tel.: +1 (814) 863-5721; Fax: +1 (814) 863-6217, E-mail address: jgf3@psu.edu

Abstract

Two pathways for cysteine biosynthesis are known in nature; however, it is not known which, if either, the Archaea utilize. Enzyme activities in extracts of Methanosarcina thermophila grown with combinations of cysteine and sulfide as sulfur sources indicated that this archaeon utilizes the pathway found in the Bacteria domain. The genes encoding serine transacetylase and O-acetylserine sulfhydrylase (cysE and cysK) are adjacent on the chromosome of M. thermophila and possibly form an operon. When M. thermophila is grown with cysteine as the sole sulfur source, O-acetylserine sulfhydrylase activity is maximally expressed suggesting alternative roles for this enzyme apart from cysteine biosynthesis.

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