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Structural basis of the inhibition of cystathionine γ‐lyase from Toxoplasma gondii by propargylglycine and cysteine

DOI: 10.1002/pro.4619 DOI Help

Authors: Carmen Fernández-Rodríguez (Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA)) , Carolina Conter (University of Verona) , Iker Oyenarte (Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA)) , Filippo Favretto (University of Verona) , Iban Quintana (TEKNIKER, Basque Research and Technology Alliance (BRTA)) , Maria Luz Martinez-Chantar (Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA)) , Alessandra Astegno (University of Verona) , Luis Alfonso Martinez-Cruz (Center for Cooperative Research in Biosciences (CIC bioGUNE))
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Protein Science

State: Published (Approved)
Published: March 2023
Diamond Proposal Number(s): 28360

Abstract: Cystathionine γ-lyase (CGL) is a PLP-dependent enzyme that catalyzes the last step of the reverse transsulfuration route for endogenous cysteine biosynthesis. The canonical CGL-catalyzed process consists of an α,γ-elimination reaction that breaks down cystathionine into cysteine, α-ketobutyrate, and ammonia. In some species, the enzyme can alternatively use cysteine as a substrate, resulting in the production of hydrogen sulfide (H2S). Importantly, inhibition of the enzyme and consequently of its H2S production activity, makes multiresistant bacteria considerably more susceptible to antibiotics. Other organisms, such as Toxoplasma gondii, the causative agent of toxoplasmosis, encode a CGL enzyme (TgCGL) that almost exclusively catalyzes the canonical process, with only minor reactivity to cysteine. Interestingly, the substitution of N360 by a serine (the equivalent amino acid residue in the human enzyme) at the active site changes the specificity of TgCGL for the catalysis of cystathionine, resulting in an enzyme that can cleave both the CγS and the CβS bond of cystathionine. Based on these findings and to deepen the molecular basis underlying the enzyme-substrate specificity, we have elucidated the crystal structures of native TgCGL and the variant TgCGL-N360S from crystals grown in the presence of cystathionine, cysteine, and the inhibitor D,L-propargylglycine (PPG). Our structures reveal the binding mode of each molecule within the catalytic cavity and help explain the inhibitory behavior of cysteine and PPG. A specific inhibitory mechanism of TgCGL by PPG is proposed.

Journal Keywords: Reverse transsulfuration; Toxoplasma gondii; cystathionine γ-lyase; cysteine; propargylglycine; inhibitor; pyridoxal-5'-phosphate; crystal structure

Diamond Keywords: Toxoplasmosis; Enzymes

Subject Areas: Biology and Bio-materials

Instruments: I03-Macromolecular Crystallography , I24-Microfocus Macromolecular Crystallography

Other Facilities: XALOC at ALBA

Added On: 12/03/2023 20:12

Discipline Tags:

Infectious Diseases Health & Wellbeing Structural biology Life Sciences & Biotech Parasitology

Technical Tags:

Diffraction Macromolecular Crystallography (MX)