title: Characterization of C-S lyase from Lactobacillus delbrueckii subsp. bulgaricus ATCC BAA-365 and its potential role in food flavour applications.
abstract: Volatile thiols have substantial impact on the aroma of many beverages and foods. Thus, the control of their formation, which has been linked to C-S lyase enzymatic activities, is of great significance in industrial applications involving food flavours. Herein, we have carried out a spectroscopic and functional characterization of a putative pyridoxal 5'-phosphate (PLP)-dependent C-S lyase from the lactic acid bacterium Lactobacillus delbrueckii subsp. bulgaricus ATCC BAA-365 (LDB C-S lyase). Recombinant LDB C-S lyase exists as a tetramer in solution and shows spectral properties of enzymes containing PLP as cofactor. The enzyme has a broad substrate specificity toward sulphur-containing amino acids with aminoethyl-L-cysteine and L-cystine being the most effective substrates over L-cysteine and L-cystathionine. Notably, the protein also reveals cysteine-S-conjugate β-lyase activity in vitro, and is able to cleave a cysteinylated substrate precursor into the corresponding flavour-contributing thiol, with a catalytic efficiency higher than L-cystathionine. Contrary to similar enzymes of other lactic acid bacteria however, LDB C-S lyase is not capable of α,γ-elimination activity towards L-methionine to produce methanethiol, which is a significant compound in flavour development. Based on our results, future developments can be expected regarding the flavour-forming potential of Lactobacillus C-S lyase and its use in enhancing food flavours.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Allegrini
authors.forename: Alessandra
authors.initials: A
authors.lastname: Astegno
authors.forename: Valentina
authors.initials: V
authors.lastname: La Verde
authors.forename: Paola
authors.initials: P
authors.lastname: Dominici
mesh_terms: D000465:Algorithms; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013437:Carbon-Sulfur Lyases / Q000378:metabolism; D003540:Cystathionine / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D057075:Enzyme Assays / Q000379:methods; D005421:Flavoring Agents / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D048668:Lactobacillus delbrueckii / Q000201:enzymology* / Q000235:genetics; D008190:Lyases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D055503:Protein Multimerization; D011732:Pyridoxal Phosphate / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013053:Spectrophotometry; D013379:Substrate Specificity; D013457:Sulfur Compounds / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D005421:Flavoring Agents; D011994:Recombinant Proteins; D013457:Sulfur Compounds; D003540:Cystathionine; D011732:Pyridoxal Phosphate; D008190:Lyases; D013437:Carbon-Sulfur Lyases; C033511:carbon-sulfur lyase; C108902:cysteine-S-conjugate beta-lyase; D003545:Cysteine
keywords: C-S lyase; PLP-dependent enzymes; lactic acid bacteria; volatile sulphur compounds; α,β-elimination