Molecular cloning and expression of key enzymes for biosynthesis of cysteine and related secondary non-protein amino acids

Abstract

Cysteine synthase plays a key role in the sulfur assimilation pathway in plant cells. The cDNA clones encoding two isoforms of this enzyme were isolated from spinach by synthetic oligonucleotide probes. The modes of expression of these two genes differed in tissues of spinach. A heterologous expression system in Escherichia coli and transgenic tobacco was made. The application of heterologous expression to modify sulfur metabolism and to produce non-protein amino acids is discussed.Abbreviation: CSase -cysteine synthase

Functional analysis of the cysteine synthase protein complex from plants: Structural, biochemical and regulatory properties

“…OAS-TL-like proteins can be involved in the synthesis of secondary plant products (Noji et al, 1993;Saito et al, 1994) and indeed the E. coli CysM protein has been engineered for the fermentative production of unnatural amino acids (Maier, 2003). Three OAS-TL isoforms A1 (cytosolic), B (plastidic) and C (mitochondrial) and a structurally related b-cyanoalanine synthase (CAS, AtCysC1) (Hatzfeld et al, 2000;Yamaguchi et al, 2000) give rise to the dominating OAS-like mRNAs according to the GeneInvestigator database and individual studies (Hell et al, 1994;Hesse et al, 1999;Hatzfeld et al, 2000).…”