Competitive Repression of the artPIQM Operon for Arginine and Ornithine Transport by Arginine Repressor and Leucine-Responsive Regulatory Protein in Escherichia coli

Abstract

Two out of the three major uptake systems for arginine in Escherichia coli are encoded by the artJ - artPIQM gene cluster. ArtJ is the high-affinity periplasmic arginine-specific binding protein (ArgBP-I), whereas artI encodes the arginine and ornithine periplasmic binding protein (AO). Both ArtJ and ArtI are supposed to combine with the inner membrane-associated ArtQMP 2 transport complex of the ATP-binding cassette-type (ABC). Transcription of artJ is repressed by arginine repressor (ArgR) and the artPIQM operon is regulated by the transcriptional regulators ArgR and Leucine-responsive regulatory protein (Lrp). Whereas repression by ArgR requires arginine as corepressor, repression of P artP by Lrp is partially counteracted by leucine, its major effector molecule. We demonstrate that binding of dimeric Lrp to the artP control region generates four complexes with a distinct migration velocity, and that leucine has an effect on both global binding affinity and cooperativity in the binding. We identify the binding sites for Lrp in the artP control region, reveal interferences in the binding of ArgR and Lrp in vitro and demonstrate that the two transcription factors act as competitive repressors in vivo , each one being a more potent regulator in the absence of the other. This competitive behavior may be explained by the partial steric overlap of their respective binding sites. Furthermore, we demonstrate ArgR binding to an unusual position in the control region of the lrp gene, downstream of the transcription initiation site. From this unusual position for an ArgR-specific operator, ArgR has little direct effect on lrp expression, but interferes with the negative leucine-sensitive autoregulation exerted by Lrp. Direct arginine and ArgR-dependent repression of lrp could be observed with a 25-bp deletion mutant, in which the ArgR binding site was artificially moved to a position immediately downstream of the lrp transcription initiation site. This finding is reminiscent of a previous observation made for the carAB operon encoding carbamoylphosphate synthase, where ArgR bound in overlap with the downstream promoter P2 does not block transcription initiated 67 bp upstream at the P1 promoter, and further supports the hypothesis that ArgR does not act as an efficient roadblock.

l -Arginine sensing regulates virulence gene expression and disease progression in enteric pathogens

“…The role of ArgR in the arginine biosynthetic pathway is well characterized. A single hexameric ArgR binds to a tandem pair of ARG box sequences in an arginine-dependent fashion (9). In EHEC, the majority of the LEE genes are organized in five major operons (LEE1-5) ( Fig.…”

“…Biochemical and structural analyses have shown that the ArgR monomer consists of two domains separated by a proteaseaccessible linker: An N-terminal DNA-binding domain and a C-terminal arginine-binding domain (8). L-Arginine binding is required for ArgR oligomerization (9,10). Mechanistically, in the presence of arginine, two trimers of ArgR dimerize forming a hexamer, which can bind to whole ARG boxes present in promoter regions, while trimeric ArgR still binds to half of the ARG box in the absence of L-arginine (11).…”

Dissecting Efficacy and Metabolic Characteristic Mechanism of Taxifolin on Renal Fibrosis by Multivariate Approach and Ultra-Performance Liquid Chromatography Coupled With Mass Spectrometry-Based Metabolomics Strategy

“…Ornithine can be used for nutritional supplementation, acute and chronic liver diseases such as cirrhosis, fatty liver, hyperammonemia caused by hepatitis, and central nervous system symptoms. The ornithine cycle converts the more toxic ammonia produced by protein metabolism in the body into the less toxic urea, which is excreted from the body ( Montaguth et al, 2019 ). Cyclic GMP, an important inhibitor of RF synthesized by guanylate cyclase stimulated by nitric oxide or natriuretic peptide, has pleiotropic regulatory functions in the kidney ( Lieb et al, 2009 ).…”

Functional Metabolomics Analysis Elucidating the Metabolic Biomarker and Key Pathway Change Associated With the Chronic Glomerulonephritis and Revealing Action Mechanism of Rhein

“…The ornithine cycle converts the more toxic ammonia produced by protein metabolism in the body into the less toxic urea, which is excreted from the body. Arginine is the precursor of ornithine and proline, which proline is an important element constituting collagen, and arginine supplementation play a vital role in severe tissue repair (Torres Montaguth et al, 2019;Li H. et al, 2019). 5'-methylthioadenosine (MTA) is a nucleoside produced from s-adenosylmethionine (AdoMet) during polyamine synthesis.…”