1. Identification and Characterization of Bacterial Alliinase: Resource and Substrate Stereospecificity.
- Author
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Liu Y, Li Y, Peng Y, Feng L, Wang W, Li C, Zhang Y, Wang R, Li C, Ma C, and Yang C
- Subjects
- Amino Acid Sequence, Bacillus cereus enzymology, Bacillus cereus genetics, Bacteria classification, Bacteria enzymology, Bacteria genetics, Carbon-Sulfur Lyases metabolism, Carbon-Sulfur Lyases genetics, Carbon-Sulfur Lyases chemistry, Cysteine analogs & derivatives, Disulfides chemistry, Disulfides metabolism, Kinetics, Phylogeny, Stereoisomerism, Substrate Specificity, Sulfinic Acids chemistry, Sulfinic Acids metabolism, Bacterial Proteins genetics, Bacterial Proteins metabolism, Bacterial Proteins chemistry, Garlic enzymology, Garlic microbiology
- Abstract
Limited alliinase resources cause difficulties in the biosynthesis of thiosulfinates (e.g., allicin), restricting their applications in the agricultural and food industries. To effectively biosynthesize thiosulfinates, this study aimed to excavate bacterial alliinase resources and elucidate their catalytic properties. Two bacterial cystathionine β-lyases (MetCs) possessing high alliinase activity (>60 U mg
-1 ) toward L-(-)-alliin were identified from Allium sativum rhizosphere isolates. Metagenomic exploration revealed that cystathionine β-lyase from Bacillus cereus (BcPatB) possessed high activity toward both L-(±)-alliin and L-(+)-alliin (208.6 and 225.1 U mg-1 ), respectively. Although these enzymes all preferred l-cysteine S-conjugate sulfoxides as substrates, BcPatB had a closer phylogenetic relationship with Allium alliinases and shared several similar features with A. sativum alliinase. Interestingly, the Trp30 Ile31 Ala32 Asp33 Met34 motif in a cuspate loop of BcPatB, especially sites 31 and 32 at the top of the motif, was modeled to locate near the sulfoxide of L-(+)-alliin and is important for substrate stereospecificity. Moreover, the stereoselectivity and activity of mutants I31V and A32G were higher toward L-(+)-alliin than those of mutant I31L/D33E toward L-(-)-alliin. Using bacterial alliinases and chemically synthesized substrates, we obtained thiosulfinates with high antimicrobial and antinematode activities that could provide insights into the protection of crops and food.- Published
- 2024
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