The crystal structure of cystathionine γ-synthase from Nicotiana tabacum reveals its substrate and reaction specificity

Steegborn, Clemens; Messerschmidt, Albrecht; Laber, Bernd; Streber, W.; Huber, Robert; Clausen, Tim

doi:10.1006/jmbi.1999.2935

Cited by 41 publications

(39 citation statements)

References 33 publications

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“…1). 2,3 The structural similarity of the eCGS (1CS1) and nCGS (1I41) is demonstrated by the r.m.s. deviation of only 2.04 Å for $350 C a atoms, the majority of the peptide backbone.…”

Section: Introductionmentioning

confidence: 94%

“…deviation of only 2.04 Å for $350 C a atoms, the majority of the peptide backbone. 3,4 Additionally, the r.m.s. deviation is only 0.3 Å between the native and inhibitor-bound forms of nCGS.…”

Section: Introductionmentioning

confidence: 99%

“…2 However, the difference in the activated Lhomoserine substrates and the active sites of the plant and bacterial enzymes complicates the use of these structures as a model for eCGS. [2][3][4] Additionally, no information is available concerning the binding site of L-Cys. The side chains of R48, R106, Y101, S326, and R361 and those of E45, R49, and E325 were proposed to bind the L-OSHS and L-Cys substrates, respectively, of eCGS.…”

Section: Introductionmentioning

confidence: 99%

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Exploration of the active site of Escherichia coli cystathionine γ‐synthase

et al. 2012

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Cystathionine c-synthase (CGS) catalyzes the condensation of O-succinyl-L-homoserine (L-OSHS) and L-cysteine (L-Cys), to produce L-cystathionine (L-Cth) and succinate, in the first step of the bacterial transsulfuration pathway. In the absence of L-Cys, the enzyme catalyzes the futile a,c-elimination of L-OSHS, yielding succinate, a-ketobutyrate, and ammonia. A series of 16 sitedirected variants of Escherichia coli CGS (eCGS) was constructed to probe the roles of active-site residues D45, Y46, R48, R49, Y101, R106, N227, E325, S326, and R361. The effects of these substitutions on the catalytic efficiency of the a,c-elimination reaction range from a reduction of only~2-fold for R49K and the E325A,Q variants to 310-and 760-fold for R361K and R48K, respectively. A similar trend is observed for the k cat /K l-OSHS m of the physiological, a,c-replacement reaction. The results of this study suggest that the arginine residues at positions 48, 106 and 361 of eCGS, conserved in bacterial CGS sequences, tether the distal and a-carboxylate moieties, respectively, of the L-OSHS substrate. In contrast, with the exception of the 13-fold increase observed for R106A, the K l-Cys m is not markedly affected by the site-directed replacement of the residues investigated. The decrease in k cat observed for the S326A variant reflects the role of this residue in tethering the side chain of K198, the catalytic base. Although no structures exist of eCGS bound to active-site ligands, the roles of individual residues is consistent with the structures inhibitor complexes of related enzymes. Substitution of D45, E325, or Y101 enables a minor transamination activity for the substrate L-Ala.

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“…1). 2,3 The structural similarity of the eCGS (1CS1) and nCGS (1I41) is demonstrated by the r.m.s. deviation of only 2.04 Å for $350 C a atoms, the majority of the peptide backbone.…”

Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Exploration of the active site of Escherichia coli cystathionine γ‐synthase

et al. 2012

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“…Induction of folate deficiency by chemical inhibitors revealed yet another mechanism of cystathionine γ-synthase regulation, in this case a post-translational proteolytic removal of the N-terminal regulatory part of the protein (Loizeau et al, 2007). The crystal structure of tobacco cystathionine γ-synthase shows that the Nterminal domain is outside of the protein globule and probably accessible to proteases (Steegborn et al, 1999). Similar to the case of the internally deleted protein (Hacham et al, 2006), proteolytic removal of the regulatory domain increases cystathionine γ-synthase activity and thereby the production of methionine and S-adenosylmethionine (Loizeau et al, 2007).…”

Section: Methionine Biosynthesismentioning

confidence: 99%

Aspartate-Derived Amino Acid Biosynthesis inArabidopsis thaliana

Jander

Joshi

2009

The Arabidopsis Book

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The aspartate-derived amino acid pathway in plants leads to the biosynthesis of lysine, methionine, threonine, and isoleucine. These four amino acids are essential in the diets of humans and other animals, but are present in growthlimiting quantities in some of the world's major food crops. Genetic and biochemical approaches have been used for the functional analysis of almost all Arabidopsis thaliana enzymes involved in aspartate-derived amino acid biosynthesis. The branch-point enzymes aspartate kinase, dihydrodipicolinate synthase, homoserine dehydrogenase, cystathionine gamma synthase, threonine synthase, and threonine deaminase contain well-studied sites for allosteric regulation by pathway products and other plant metabolites. In contrast, relatively little is known about the transcriptional regulation of amino acid biosynthesis and the mechanisms that are used to balance aspartatederived amino acid biosynthesis with other plant metabolic needs. The aspartate-derived amino acid pathway provides excellent examples of basic research conducted with A. thaliana that has been used to improve the nutritional quality of crop plants, in particular to increase the accumulation of lysine in maize and methionine in potatoes.

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“…The first CGS structure was solved for the Escherichia coli enzyme covalently linked to the cofactor PLP (Clausen et al, 1998) and was followed by a structure of CGS from the plant Nicotiana tabacum also covalently linked to PLP (Steegborn et al, 1999). Steegborn and coworkers also solved a series of structures bound to a variety of inhibitors as potential herbicides (Steegborn et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Structure of the cystathionine γ-synthase MetB fromMycobacterium ulcerans

et al. 2011

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PDB References: MyulA.00906.a, 3qi6; 3qhx.Cystathionine -synthase (CGS) is a transulfurication enzyme that catalyzes the first specific step in l-methionine biosynthesis by the reaction of O 4 -succinyll-homoserine and l-cysteine to produce l-cystathionine and succinate. Controlling the first step in l-methionine biosythesis, CGS is an excellent potential drug target. Mycobacterium ulcerans is a slow-growing mycobacterium that is the third most common form of mycobacterial infection, mainly infecting people in Africa, Australia and Southeast Asia. Infected patients display a variety of skin ailments ranging from indolent non-ulcerated lesions as well as ulcerated lesions. Here, the crystal structure of CGS from M. ulcerans covalently linked to the cofactor pyridoxal phosphate (PLP) is reported at 1.9 Å resolution. A second structure contains PLP as well as a highly ordered HEPES molecule in the active site acting as a pseudo-ligand. These results present the first structure of a CGS from a mycobacterium and allow comparison with other CGS enzymes. This is also the first structure reported from the pathogen M. ulcerans.

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The crystal structure of cystathionine γ-synthase from Nicotiana tabacum reveals its substrate and reaction specificity

Cited by 41 publications

References 33 publications

Exploration of the active site of Escherichia coli cystathionine γ‐synthase

Exploration of the active site of Escherichia coli cystathionine γ‐synthase

Aspartate-Derived Amino Acid Biosynthesis inArabidopsis thaliana

Structure of the cystathionine γ-synthase MetB fromMycobacterium ulcerans

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