Crystal Structures of Cystathionine β-Synthase from Saccharomyces cerevisiae: One Enzymatic Step at a Time.
Yupeng TuCheryl A KreinbringMegan HillCynthia LiuGregory A PetskoChristopher D McCuneDavid B BerkowitzDali LiuDagmar RingePublished in: Biochemistry (2018)
Cystathionine β-synthase (CBS) is a key regulator of sulfur amino acid metabolism, taking homocysteine from the methionine cycle to the biosynthesis of cysteine via the trans-sulfuration pathway. CBS is also a predominant source of H2S biogenesis. Roles for CBS have been reported for neuronal death pursuant to cerebral ischemia, promoting ovarian tumor growth, and maintaining drug-resistant phenotype by controlling redox behavior and regulating mitochondrial bioenergetics. The trans-sulfuration pathway is well-conserved in eukaryotes, but the analogous enzymes have different enzymatic behavior in different organisms. CBSs from the higher organisms contain a heme in an N-terminal domain. Though the presence of the heme, whose functions in CBSs have yet to be elucidated, is biochemically interesting, it hampers UV-vis absorption spectroscopy investigations of pyridoxal 5'-phosphate (PLP) species. CBS from Saccharomyces cerevisiae (yCBS) naturally lacks the heme-containing N-terminal domain, which makes it an ideal model for spectroscopic studies of the enzymological reaction catalyzed and allows structural studies of the basic yCBS catalytic core (yCBS-cc). Here we present the crystal structure of yCBS-cc, solved to 1.5 Å. Crystal structures of yCBS-cc in complex with enzymatic reaction intermediates have been captured, providing a structural basis for residues involved in catalysis. Finally, the structure of the yCBS-cc cofactor complex generated by incubation with an inhibitor shows apparent off-pathway chemistry not normally seen with CBS.
Keyphrases
- saccharomyces cerevisiae
- drug resistant
- cerebral ischemia
- amino acid
- structural basis
- hydrogen peroxide
- multidrug resistant
- subarachnoid hemorrhage
- transcription factor
- gram negative
- blood brain barrier
- acinetobacter baumannii
- brain injury
- case control
- oxidative stress
- molecular docking
- nitric oxide
- single molecule
- magnetic resonance
- electron transfer
- pseudomonas aeruginosa
- diffusion weighted imaging
- molecular dynamics simulations
- visible light