Sarcosine Catabolism in Pseudomonas aeruginosa Is Transcriptionally Regulated by SouR

Abstract

The Pseudomonas aeruginosa genome encodes many diverse metabolic pathways, yet the specific transcription regulators controlling their expression remain mostly unknown. Here, we used a genetic screen to identify the sarcosine-specific regulator of the sarcosine oxidase operon, which we have named SouR. SouR is the first bacterial regulator shown to respond to sarcosine, and it is required for growth on sarcosine. Sarcosine is found in its free form and is also an intermediate in the catabolic pathways of glycine betaine, carnitine, creatine, and glyphosate. The similarity of SouR to the regulators of carnitine and glycine betaine catabolism suggests evolutionary diversification within this regulatory family to allow response to structurally similar but physiologically distinct ligands.

Choline Catabolism in Burkholderia thailandensis Is Regulated by Multiple Glutamine Amidotransferase 1-Containing AraC Family Transcriptional Regulators

“…Also induced was a nearby predicted operon consisting of BTH_II1855-BTH_II1853, carrying likely orthologs of P. aeruginosa betC, cosX, and a predicted porin. Another GATR, BTH_II0994, and the divergently transcribed operon consisting of BTH_II0995 (sdaA-2), BTH_II0996 (soxB), BTH_II0997 (soxD), BTH_II0998 (soxA), BTH_II0999 (soxG), and BTH_II1000, were also induced, and we hypothesized that these are the B. thailandensis souR and sarcosine oxidase genes responsible for the breakdown of sarcosine to glycine (35).…”

“…1C). P. aeruginosa uses sarcosine as a sole carbon and nitrogen source, and this is regulated by the transcription factor SouR (35). While B. thailandensis can use choline as a sole carbon or sole carbon and nitrogen source, B. thailandensis is unable to grow on sarcosine as a sole carbon source or as a sole carbon and nitrogen source (see Fig.…”

“…1A and C). SouR, also a GATR, controls transcriptional induction of the sarcosine oxidase genes in response to sarcosine (35). Homologs of betI and betBA in B. thailandensis have been described previously (38).…”

“…cDNA was generated using a Superscript IV first-strand synthesis system (Invitrogen) using 24 ng of RNA combined with the 5=-NSNSNSNSNS-3= primer previously described (34). Quantitative PCR (qPCR) was performed as described in Willsey et al (35). Briefly, 0.2ϫ SYBR green I nucleic acid gel stain (Thermo Fisher Scientific [TFS]) was used with Q5 high-fidelity 2ϫ master mix (NEB) and amplified using cycle conditions of 98°C for 2 min and 98°C for 20 s, annealing at 60°C for 30 s, and extension at 72°C for 20 s, repeated by going back to the second step 39 times.…”

The Type Three Secretion System 2-Encoded Regulator EtrB Modulates Enterohemorrhagic Escherichia coli Virulence Gene Expression

“…The RNA processing, labeling, hybridization, and slide-scanning procedures were performed as described in the Affymetrix GeneChip Expression Analysis Technical Manual (49). Data analyses from the array were performed as previously described (50). The Affymetrix GeneChip Command Console (AGCC) software was used to obtain the output from scanning a single replicate of the Affymetrix GeneChip E. coli Genome 2.0 array for each of the biological conditions, according to the manufacturer's instructions.…”