Role of metAB in Methionine Metabolism and Optimal Chicken Colonization in Campylobacter jejuni

Abstract

Campylobacter jejuni is a zoonotic pathogen and is one of the leading causes of human gastroenteritis worldwide. C. jejuni IA3902 (representative of the sheep abortion clone) is genetically similar to C. jejuni W7 (representative of strain-type NCTC 11168), however, there are significant differences in the ability of luxS mutants of these strains to colonize chickens. LuxS is essential for the activated methyl cycle and generates homocysteine for conversion to L-methionine. Comparative genomics identified differential distribution of genes metA and metB, which function to convert homoserine for downstream production of L-methionine, between IA3902 and W7 which could enable a secondary pathway for L-methionine biosynthesis in W7ΔluxS but not in IA3902ΔluxS. To test the hypothesis that genes metA and metB contribute to L-methionine production and chicken colonization by Campylobacter, we constructed two mutants for phenotypic comparison: W7ΔmetABΔluxS and IA3902ΔluxS::metAB. Quantitative reverse transcription PCR and tandem mass spectrometry protein analysis were used to validate MetAB transcription and translation as present in IA3902ΔluxS::metAB and absent in W7ΔmetABΔluxS. Time-resolved fluorescence resonance energy transfer fluorescence assays demonstrated L-methionine and S-adenosyl methionine concentrations decreased in W7ΔmetABΔluxS and increased in IA3902ΔluxS::metAB. Assessment of chicken colonization revealed that IA3902ΔluxS::metAB partially rescued the colonization defect of IA3902ΔluxS, while W7ΔmetABΔluxS resulted in significantly decreased colonization compared to the wild type and W7ΔluxS. These results indicate that the ability to maintain L-methionine production in vivo, conferred by metA and metB in the absence of luxS, is critical for normal chicken colonization by C. jejuni.

Direct interaction of small non-coding RNAs CjNC140 and CjNC110 optimizes expression of key pathogenic phenotypes of Campylobacter jejuni

“…In our previous work, ∆CjNC110 was also demonstrated to function within the activated methyl cycle (AMC) to increase the expression of LuxS and alter the localization of its secondary biproduct, AI-2 ( 20 , 25 ). To determine if CjNC140 also regulates within the AMC, bioluminescence assays were first performed to measure biosynthesis and localization of AI-2 as described previously ( 20 ).…”

“…The coupled increase in AI-2 production both extracellularly and intracellularly in ∆CjNC140 suggested positive feedback within the AMC was occurring following mutagenesis of CjNC140. To further investigate the effects of CjNC140 and CjNC110 on the AMC, L-met and SAM metabolite concentrations were quantified using TR-FRET florescence assays as previously reported ( 25 ). For ∆CjNC140, L-met concentration significantly ( P < 0.05) increased, while ∆CjNC140c demonstrated significantly ( P < 0.05) decreased L-met concentration relative to IA3902 WT ( Fig.…”

Interplay of two small RNAs fine-tunes hierarchical flagellar gene expression in the foodborne pathogenCampylobacter jejuni

“…In C. jejuni strain 81-176, the Cj1387c ortholog (HeuR, heme uptake regulator) promotes chicken colonization and regulates iron metabolism and methionine biosynthesis, possibly via direct binding to promoter regions (Johnson et al, 2016;Kelley et al, 2021). This points to an additional role for FlmE not only in regulating flagellar biosynthesis, but also in important metabolic pathways via repression of Cj1387c, thus connecting these infection-relevant processes (Crofts et al, 2018;Liu et al, 2018;Ruddell et al, 2020).…”

Antibiotic Resistance of the Campylobacter Isolates According to Their Species in Different Samples of Broiler Chicken in Many Regions

“…Campylobacteriosis is caused pathogenic bacterial species of the genus Campylobacter, which in humans most often cause symptoms of acute food poisoning (Ruddell et al 2020). Campylobacteriosis of humans belongs to the seasonal zoonoses, food poisoning diseases that most often occur in the warm season when the most favorable climatic conditions for the growth and development of these pathogens in food (Kaakoush et al 2015;Hrustemović et al 2022b).…”