Transcriptional Regulation of Cysteine and Methionine Metabolism in Lactobacillus paracasei FAM18149

Abstract

Lactobacillus paracasei is common in the non-starter lactic acid bacteria (LAB) community of raw milk cheeses. This species can significantly contribute to flavor formation through amino acid metabolism. In this study, the DNA and RNA of L. paracasei FAM18149 were sequenced using next-generation sequencing technologies to reconstruct the metabolism of the sulfur-containing amino acids cysteine and methionine. Twenty-three genes were found to be involved in cysteine biosynthesis, the conversion of cysteine to methionine and vice versa, the S-adenosylmethionine recycling pathway, and the transport of sulfur-containing amino acids. Additionally, six methionine-specific T-boxes and one cysteine-specific T-box were found. Five of these were located upstream of genes encoding transporter functions. RNA-seq analysis and reverse-transcription quantitative polymerase reaction assays showed that expression of genes located downstream of these T-boxes was affected by the absence of either cysteine or methionine. Remarkably, the cysK2-ctl1-cysE2 operon, which is associated with te methionine-to-cysteine conversion and is upregulated in the absence of cysteine, showed high read coverage in the 5′-untranslated region and an antisense-RNA in the 3′-untranslated region. This indicates that this operon is regulated by the combination of cis- and antisense-mediated regulation mechanisms. The results of this study may help in the selection of L. paracasei strains to control sulfuric flavor formation in cheese.

AhR Activation Leads to Alterations in the Gut Microbiome with Consequent Effect on Induction of Myeloid Derived Suppressor Cells in a CXCR2-Dependent Manner

“…In the current report, TCDD reduced cysteine and methionine metabolism, as evidenced through examination by PICRUSt; these results were validated, showing cysteine levels in the peritoneal cavity and colon exudates were decreased after TCDD exposure. The reason behind cysteine reduction after TCDD exposure could be attributed to sequestering by MDSCs, or it could also be attributed to an increase in bacteria, such as Lactobacillus , which use cysteine as a sulfur source to grow [ 54 ]. It was thus interesting that when cysteine was provided in culture, it reversed the suppression of T-cell proliferation mediated by MDSCs.…”

Conversion of Methionine to Cysteine in Lactobacillus paracasei Depends on the Highly Mobile cysK-ctl-cysE Gene Cluster

“…Additionally, a model was published that explained the role of ctl in the volatile sulfur compounds production ( Bogicevic et al, 2013 ). Finally, we recently published that the cysK-ctl-cysE is massively up regulated in L. paracasei , if no cysteine is present in the growth medium ( Wüthrich et al, 2018 ).…”

How the Fewest Become the Greatest. L. casei’s Impact on Long Ripened Cheeses

“…Peptides and aminoacids, increasing along with the ripening progress, constitute the main nutritional compounds for NSLAB ( Fox et al, 2004 ; Settanni and Moschetti, 2010 ; Settanni and Moschetti, 2010 ). L. rhamnosus strains, as an example, have been linked to arginine catabolism in ripened cheeses ( D’Incecco et al, 2016 ), and the metabolism of the sulfur-containing amino acids cysteine and methionine has been described for one Lactobacillus paracasei strain ( Wüthrich et al, 2018 ) However, NSLAB can also utilize carbohydrates deriving from glycomacropeptides of caseins, glycoproteins from fat globule membranes, pentoses and other products from SLAB lysis and residual citrate ( Fox et al, 2004 ; Sgarbi et al, 2013a ). Through citrate metabolism, acetoin is produced, while by degradation of amino acids produces other ketones that are considered common constituents of cheese aroma ( McSweeney and Sousa, 2000 ; Curioni and Bosset, 2002 ; Marilley and Casey, 2004 ).…”