Perturbation of the metabolic network in Salmonella enterica reveals cross-talk between coenzyme A and thiamine pathways

Abstract

Microorganisms respond to a variety of metabolic perturbations by repurposing or recruiting pathways to reroute metabolic flux and overcome the perturbation. Elimination of the 2-dehydropantoate 2-reductase, PanE, both reduces total coenzyme A (CoA) levels and causes a conditional HMP-P auxotrophy in Salmonella enterica. CoA or acetyl-CoA has no demonstrable effect on the HMP-P synthase, ThiC, in vitro. Suppressors aimed at probing the connection between the biosynthesis of thiamine and CoA contained mutations in the gene encoding the ilvC transcriptional regulator, ilvY. These mutations may help inform the structure and mechanism of action for the effector-binding domain, as they represent the first sequenced substitutions in the effector-binding domain of IlvY that cause constitutive expression of ilvC. Since IlvC moonlights as a 2-dehydropantoate 2-reductase, the resultant increase in ilvC transcription increased synthesis of CoA. This study failed to identify mutations overcoming the need for CoA for thiamine synthesis in S. enterica panE mutants, suggesting that a more integrated approach may be necessary to uncover the mechanism connecting CoA and ThiC activity in vivo.

CRISPR/dCas9-RpoD-Mediated Simultaneous Transcriptional Activation and Repression in Shewanella oneidensis MR-1

“…To enable transcriptional activation, we developed a CRISPR/dCas9-activator system, and two types of activators were selected. One type is to directly recruit the RNAP holoenzyme (Figure a), including Escherichia coli DNA-binding transcriptional regulator soxS , endogenous RNAP subunits rpoZ (ω) and rpoS (σ38), RNAP interacting proteins dksA , SO_1986 , SO_3096 , SO_3551 , and fliA , and genetic regulators ilvY , crp , nhaR , hexR , pdhR , oxyR , and ohrR (Figure b). The other type is σ 70 encoded by rpoD (Figure b), which was able to recruit the RNAP core enzyme to form holoenzymes to initiate transcription.…”

The Cysteine Desulfurase IscS Is a Significant Target of 2-Aminoacrylate Damage in Pseudomonas aeruginosa

“…In S. enterica , DapA variants that suppressed ridA mutant phenotypes had, on average, a 50-fold lower specific activity than the wild-type enzyme. These variants increased metabolic flux toward threonine, ultimately decreasing the IlvA-mediated generation of 2AA ( 20 , 21 ). Residue N108 is adjacent to Y107 ( E. coli numbering), a conserved active site residue that significantly lowers DapA activity when disrupted ( 20 , 22 ).…”

“…The lesion in dapA was predicted to act by the mechanism characterized for lesions in the same locus in S. enterica . Briefly, lowering the activity of DapA increases flux to threonine/isoleucine which reduces 2AA formation by IlvA ( 20 , 21 ). Suppressing lesions in dapA and PA1559 restored transaminase B (IlvE) activity in the P. aeruginosa ridA mutant, indicating they had reduced endogenous levels of 2AA.…”

Study on inhibitory effect of cinnamaldehyde on Salmonella based on iTRAQ technology

“…CR079_08520 and ilvH, acetolactate synthase regulatory subunit I and III, were down-regulated cocultured with cinnamaldehyde. ilvD and ilvC mediates the synthesis of BCAAs in Salmonella, and the latter promotes the synthesis of coenzyme A [26]. rpiA plays a significant role in energy carbohydrate anabolism and catabolism [27].…”