A continuous spectrophotometric assay and nonlinear kinetic analysis of methionine γ-lyase catalysis

Foo, Timothy C; Terentis, Andrew C.; Venkatachalam, K.V.

doi:10.1016/j.ab.2016.05.010

Cited by 5 publications

(3 citation statements)

References 32 publications

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“…The common conserved domain predicted in these MegLs belongs to the AAT_I superfamily. Within the domain, several functional elements were recognized, including the catalytic residue and pyridoxal 5′-phosphate binding site, which are two typical structural characteristics of MegLs [ 57 ]. Additionally, a substrate–cofactor binding pocket and homodimer interface were also found in them.…”

Section: Resultsmentioning

confidence: 99%

Quorum Sensing Regulates the Production of Methanethiol in Vibrio harveyi

Zhou,

Wang,

Todd

et al. 2023

Microorganisms

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Methanethiol (MeSH) and dimethyl sulfide (DMS) are important volatile organic sulfur compounds involved in atmospheric chemistry and climate regulation. However, little is known about the metabolism of these compounds in the ubiquitous marine vibrios. Here, we investigated MeSH/DMS production and whether these processes were regulated by quorum-sensing (QS) systems in Vibrio harveyi BB120. V. harveyi BB120 exhibited strong MeSH production from methionine (Met) (465 nmol mg total protein−1) and weak DMS production from dimethylsulfoniopropionate (DMSP) cleavage. The homologs of MegL responsible for MeSH production from L-Met widely existed in vibrio genomes. Using BB120 and its nine QS mutants, we found that the MeSH production was regulated by HAI-1, AI-2 and CAI-1 QS pathways, as well as the luxO gene located in the center of this QS cascade. The regulation role of HAI-1 and AI-2 QS systems in MeSH production was further confirmed by applying quorum-quenching enzyme MomL and exogenous autoinducer AI-2. By contrast, the DMS production from DMSP cleavage showed no significant difference between BB120 and its QS mutants. Such QS-regulated MeSH production may help to remove excess Met that can be harmful for vibrio growth. These results emphasize the importance of QS systems and the MeSH production process in vibrios.

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Section: Resultsmentioning

confidence: 99%

Quorum Sensing Regulates the Production of Methanethiol in Vibrio harveyi

Zhou,

Wang,

Todd

et al. 2023

Microorganisms

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“…Interestingly, F. nucleatum released the highest amounts of CH 3 SH at pH 8.5 ( Table 1 ; Fig. 1A ), which was considered to be due to the optimal pH of METase ( l -methionine + H 2 O → CH 3 SH + NH 3 +2-oxobutanoate) of 8.0–8.5 in F. nucleatum as well as other bacteria ( 46 – 48 ). It has also been reported that an alkaline condition (pH 8.2) induces biofilm development by F. nucleatum through the increased abundance of adhesion proteins ( 49 ).…”

Section: Discussionmentioning

confidence: 96%

Interspecies metabolite transfer fuels the methionine metabolism of Fusobacterium nucleatum to stimulate volatile methyl mercaptan production

Hara,

Sakanaka,

Lamont

et al. 2024

mSystems

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The major oral odor compound methyl mercaptan (CH 3 SH) is strongly associated with halitosis and periodontitis. CH 3 SH production stems from the metabolism of polymicrobial communities in periodontal pockets and on the tongue dorsum. However, understanding of CH 3 SH-producing oral bacteria and their interactions is limited. This study aimed to investigate CH 3 SH production by major oral bacteria and the impact of interspecies interactions on its generation. Using a newly constructed large-volume anaerobic noncontact coculture system, Fusobacterium nucleatum was found to be a potent producer of CH 3 SH, with that production stimulated by metabolic interactions with Streptococcus gordonii , an early dental plaque colonizer. Furthermore, analysis of extracellular amino acids using an S. gordonii arginine-ornithine antiporter (ArcD) mutant demonstrated that ornithine excreted from S. gordonii is a key contributor to increased CH 3 SH production by F. nucleatum . Further study with 13 C, 15 N-methionine, as well as gene expression analysis, revealed that ornithine secreted by S. gordonii increased the demand for methionine through accelerated polyamine synthesis by F. nucleatum , leading to elevated methionine pathway activity and CH 3 SH production. Collectively, these findings suggest that interaction between S. gordonii and F. nucleatum plays a key role in CH 3 SH production, providing a new insight into the mechanism of CH 3 SH generation in oral microbial communities. A better understanding of the underlying interactions among oral bacteria involved in CH 3 SH generation can lead to the development of more appropriate prophylactic approaches to treat halitosis and periodontitis. An intervention approach like selectively disrupting this interspecies network could also offer a powerful therapeutic strategy. IMPORTANCE Halitosis can have a significant impact on the social life of affected individuals. Among oral odor compounds, CH 3 SH has a low olfactory threshold and halitosis is a result of its production. Recently, there has been a growing interest in the collective properties of oral polymicrobial communities, regarded as important for the development of oral diseases, which are shaped by physical and metabolic interactions among community participants. However, it has yet to be investigated whether interspecies interactions have an impact on the production of volatile compounds, leading to the development of halitosis. The present findings provide mechanistic insights indicating that ornithine, a metabolite excreted by Streptococcus gordonii , promotes polyamine synthesis by Fusobacterium nucleatum , resulting in a compensatory increase in demand for methionine, which results in elevated methionine pathway activity and CH 3 SH production. Elucidation of the mechanisms related to CH 3 SH production is expected to lead to the development of new strategies for managing halitosis.

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“…Determination of the activity of the METase was performed as described by Foo et al After 20 min reaction, 10 % (v/v) of 50 % trichloroacetic acid was added to precipitate the enzyme to stop the reaction. Samples were centrifuged and then 50 μL was transferred to a 96‐well plate with 150 μl acetic buffer (1 M, pH 5).…”

Section: Methodsmentioning

confidence: 99%

Biocatalytic Cascade Reaction for the Asymmetric Synthesis of L‐ and D‐Homoalanine

et al. 2018

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Unnatural amino acids attract growing attention for pharmaceutical applications as they are useful building blocks for the synthesis of a number of chiral drugs. Here, we describe a two‐step enzymatic method for the asymmetric synthesis of homoalanine from L‐methionine, a cheap and readily available natural amino acid. First, the enzyme L‐methionine γ‐lyase (METase), from Fusobacterium nucleatum, catalyzed the γ‐elimination of L‐methionine to 2‐oxobutyrate. Second, an amino acid aminotransferase catalyzed the asymmetric conversion of 2‐oxobutyrate to either L‐ or D‐homoalanine. The L‐branched chain amino acid aminotransferase from Escherichia coli (eBCAT), using L‐glutamate as amino donor, produced L‐homoalanine (32.5 % conv., 28 % y, 99 % ee) and the D‐amino acid aminotransferase from Bacillus sp. (DATA) used D‐alanine as amino donor to produce D‐homoalanine (87.5 % conv., 69 % y, 90 % ee). Thus, this concept allows for the first time the synthesis of both enantiomers of this important unnatural amino acid.

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A continuous spectrophotometric assay and nonlinear kinetic analysis of methionine γ-lyase catalysis

Cited by 5 publications

References 32 publications

Quorum Sensing Regulates the Production of Methanethiol in Vibrio harveyi

Quorum Sensing Regulates the Production of Methanethiol in Vibrio harveyi

Interspecies metabolite transfer fuels the methionine metabolism of Fusobacterium nucleatum to stimulate volatile methyl mercaptan production

Biocatalytic Cascade Reaction for the Asymmetric Synthesis of L‐ and D‐Homoalanine

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