Structural characterization and functional analysis of cystathionine β‐synthase: an enzyme involved in the reverse transsulfuration pathway of <i>Bacillus anthracis</i>

Devi, S. Uma; Rehman, S.A. Abdul; Tarique, K.F.; Gourinath, S.

doi:10.1111/febs.14273

Cited by 27 publications

(46 citation statements)

References 66 publications

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“…Mutation of two of these residues in Saccharomyces cerevisiae CBS ( Sc CBS) resulted in a loss of activity with substrate L‐serine and a gain of activity with OAS. Earlier reports on OCBS (Hullo et al , ; Devi et al , ; Matoba et al , ) suggested OCBS to be present only in a few bacteria, but our study revealed the presence of OCBS in a greater variety of bacteria.…”

Section: Introductioncontrasting

confidence: 73%

“…We retrieved many protein sequences annotated either as cysteine synthase or OASS from the NCBI database using PSI‐BLAST with Bacillus anthracis OCBS as the search template (due to it having previously been shown to be an OCBS [Devi et al , ]). Most of these retrieved sequences probably corresponded to OCBS, with the product of the gene hp0107 of H. pylori being one of them.…”

Section: Resultsmentioning

confidence: 99%

“…This analysis suggested the product of the hp0107 gene to be also involved in the transsulfuration pathway, where the products of all of these genes are required and thus expressed simultaneously as reported earlier (Doherty et al , ). Some recent findings also suggested (Devi et al , ; Matoba et al , ) that the product of hp0107 gene could actually be an OAS‐dependent CBS ( Hp OCBS) in H. pylori . It should be noted that the transsulfuration pathway has been indicated to be crucial for the viability of H. pylori since it grows only in L‐methionine‐rich media (Nedenskov, ; Reynolds and Penn, ; Mendz and Hazell, ), and mutations in any one of these genes have been shown to impede the growth of the organism and to result in it becoming a cysteine auxotroph (Doherty et al , ).…”

Section: Introductionmentioning

confidence: 96%

“…). Recently a few O‐acetylserine‐dependent CBSs (OCBSs) have been identified and characterized in certain bacteria, have been shown to function in the reverse transsulfuration pathway, specifically being involved in methionine‐to‐cysteine conversion that takes O‐acetylserine from the de novo pathway (Hullo et al , ; Devi et al , ; Matoba et al , ).…”

Section: Introductionmentioning

confidence: 99%

“…Bacterial OCBS also belongs to the PLP type II fold and catalyzes the synthesis of cystathionine via the β‐replacement reaction of O‐acetylserine and L‐homocysteine. OCBS has neither an N‐terminal heme‐binding region nor a C‐terminal regulatory domain (Devi et al , ; Matoba et al , ). These OCBSs are also capable of catalyzing the production of H 2 S efficiently via β‐replacement with substrate L‐cysteine and L‐homocysteine (Devi et al , ; Matoba et al , ).…”

Section: Introductionmentioning

confidence: 99%

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Identification and characterization of Helicobacter pylori O‐acetylserine‐dependent cystathionine β‐synthase, a distinct member of the PLP‐II family

Devi

Tarique

Ali

et al. 2019

Molecular Microbiology

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O-acetylserine sulfhydrylase (OASS) and cystathionine β-synthase (CBS) are members of the PLP-II family, and involved in L-cysteine production. OASS produces L-cysteine via a de novo pathway while CBS participates in the reverse transsulfuration pathway. O-acetylserine-dependent CBS (OCBS) was previously identified as a new member of the PLP-II family, which are predominantly seen in bacteria. The bacterium Helicobacter pylori possess only one OASS (hp0107) gene and we showed that the protein coded by this gene actually functions as an OCBS and utilizes L-homocysteine and O-acetylserine (OAS) to produce cystathionine. HpOCBS did not show CBS activity with the substrate L-serine and required OAS exclusively. The HpOCBS structure in complex with methionine showed a closed cleft state, explaining the initial mode of substrate binding. Sequence and structural analyses showed differences between the active sites of OCBS and CBS, and explain their different substrate preferences. We identified three hydrophobic residues near the active site of OCBS, corresponding to one serine and two tyrosine residues in CBSs. Mutational studies were performed on HpOCBS and Saccharomyces cerevisiae CBS. A ScCBS double mutant (Y158F/Y226V) did not display activity with L-serine, indicating indispensability of these polar residues for selecting substrate L-serine, however, did show activity with OAS.

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Section: Introductioncontrasting

confidence: 73%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Identification and characterization of Helicobacter pylori O‐acetylserine‐dependent cystathionine β‐synthase, a distinct member of the PLP‐II family

Devi

Tarique

Ali

et al. 2019

Molecular Microbiology

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Current Structural Knowledge on Cystathionine β‐Synthase, a Pivotal Enzyme in the Transsulfuration Pathway

González‐Recio¹,

Fernández-Rodríguez²,

Simón³

et al. 2020

Encyclopedia of Life Sciences

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Cystathionine β‐synthase (CBS), the first enzyme of the reverse transsulfuration pathway, catalyses the pyridoxal‐5′‐phosphate (PLP)‐dependent β‐replacement reaction that condenses l ‐serine with L‐homocysteine to yield cystathionine and water. Besides this canonical reaction and using cysteine and homocysteine as substrates, CBS can also efficiently produce hydrogen sulfide (H 2 S) through alternative β‐replacement and β‐elimination processes. The structural information on the full‐length enzyme has remained elusive for decades and is still very scarce, but some advances in the recent years have uncovered its peculiar modular architecture, provided a glimpse of its conformational landscape and revealed some of the reaction intermediates formed during the catalysis. All these data have helped comprehend, at least partially, the regulatory mechanisms and the catalytic abilities of the enzyme across different organisms. This article aims to overview the current information on the CBS structure from its most sophisticated variants found in mammals to its simplest homologs in bacteria. A more detailed understanding of CBS structure and function is needed, which could subsequently serve as a basis for the development of drugs to treat human diseases, such as CBS‐deficient homocystinuria, Alzheimer diseases and some cancers, as well as of new antibiotics against multidrug‐resistant pathogenic bacteria. Key Concepts Reverse transsulfuration is a two‐step metabolic route that allows the conversion of the essential amino acid methionine into cysteine. This process generates hydrogen sulfide and impedes the accumulation of the toxic intermediate homocysteine. Hydrogen sulfide is an important gasotransmitter involved in physiological functions such as neuroprotection and the regulation of blood pressure. Homocystinuria consists of the abnormal accumulation of homocysteine, and is an inherited disorder due to the deficient activity of CBS. This pathology causes vascular thromboses, skeletal defects, mental retardation, and even early death. The three‐dimensional structure of CBS provides a suitable template to develop drugs to treat homocystinuria and related pathologies in humans. The comparative structural analysis of the CBS enzymes from different organisms are key to intervene in their sulfur metabolism, and thus represents a potential therapeutic approach against pathogens.

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Key substrate recognition residues in the active site of cystathionine beta‐synthase from Toxoplasma gondii

et al. 2023

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Cystathionine β‐synthase (CBS) catalyzes the condensation of l‐serine and l‐homocysteine to give l‐cystathionine in the transsulfuration pathway. Recently, a few O‐acetylserine (l‐OAS)‐dependent CBSs (OCBSs) have been found in bacteria that can exclusively function with l‐OAS. CBS from Toxoplasma gondii (TgCBS) can efficiently use both l‐serine and l‐OAS to form l‐cystathionine. In this work, a series of site‐specific variants substituting S84, Y160, and Y246 with hydrophobic residues found at the same positions in OCBSs was generated to explore the roles of the hydroxyl moieties of these residues as determinants of l‐serine/l‐OAS preference in TgCBS. We found that the S84A/Y160F/Y246V triple mutant behaved like an OCBS in terms of both substrate requirements, showing β‐replacement activity only with l‐OAS, and pH optimum, which is decreased by ~1 pH unit. Formation of a stable aminoacrylate upon reaction with l‐serine is prevented by the triple mutation, indicating the importance of the H‐bonds between the hydroxyl groups of Y160, Y246, and S84 with l‐serine in formation of the intermediate. Analysis of the independent effect of each mutation on TgCBS activity and investigation of the protein–aminoacrylate complex structure allowed for the conclusion that the hydroxyl group of Y246 has a major, but not exclusive, role in controlling the l‐serine preference by efficiently stabilizing its leaving group. These studies demonstrate that differences in substrate specificity of CBSs are controlled by natural variations in as few as three residue positions. A better understanding of substrate specificity in TgCBS will facilitate the design of new antimicrobial compounds.

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Structural characterization and functional analysis of cystathionine β‐synthase: an enzyme involved in the reverse transsulfuration pathway of Bacillus anthracis

Abstract: Structural data are available in the PDB under the accession number 5XW3.

Cited by 27 publications

References 66 publications

Identification and characterization of Helicobacter pylori O‐acetylserine‐dependent cystathionine β‐synthase, a distinct member of the PLP‐II family

Identification and characterization of Helicobacter pylori O‐acetylserine‐dependent cystathionine β‐synthase, a distinct member of the PLP‐II family

Current Structural Knowledge on Cystathionine β‐Synthase, a Pivotal Enzyme in the Transsulfuration Pathway

Key substrate recognition residues in the active site of cystathionine beta‐synthase from Toxoplasma gondii

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