Inactivation of PadR, the Repressor of the Phenolic Acid Stress Response, by Molecular Interaction with Usp1, a Universal Stress Protein fromLactobacillus plantarum, inEscherichia coli

Abstract

The phenolic acid decarboxylase gene padA is involved in the phenolic acid stress response (PASR) in gram-positive bacteria. In Lactobacillus plantarum, the padR gene encodes the negative transcriptional regulator of padA and is cotranscribed with a downstream gene, usp1, which encodes a putative universal stress protein (USP), Usp1, of unknown function. The usp1 gene is overexpressed during the PASR. However, the role and the mechanism of action of the USPs are unknown in gram-positive bacteria. Therefore, to gain insights into the role of USPs in the PASR; (i) a usp1 deletion mutant was constructed; (ii) the two genes padR and usp1 were coexpressed with padA under its own promoter as a reporter gene in Escherichia coli; and (iii) molecular in vitro interactions between the PadR, Usp1, and the padA promoter were studied. Although the usp1 mutant strain retained phenolic acid-dependent PAD activity, it displayed a greater sensitivity to strong acidic conditions compared to that of the wild-type strain. PadR cannot be inactivated directly by phenolic acid in E. coli recombinant cultures but is inactivated by Usp1 when the two proteins are coexpressed in E. coli. The PadR inactivation observed in recombinant E. coli cells was supported by electrophoretic mobility shift assays. Although Usp1 seems not to be absolutely required for the PASR, its capacity to inactivate PadR indicates that it could serve as an important mediator in acid stress response mechanisms through its capacity to interact with transcriptional regulators.

Genetic and Biochemical Analysis of PadR- padC Promoter Interactions during the Phenolic Acid Stress Response in Bacillus subtilis 168

“…Wildtype and mutant B. subtilis 168 strains grown in LB medium were harvested and disrupted using a Z Plus series cell disrupter (Constant system) (15). PAD activity in cell extracts was measured by monitoring the kinetics of absorption peaks by UV spectrophotometry (6).…”

“…These acids can be released by cinnamonyl esterase activities, which are expressed by various microorganisms (10,12,27) and in their free form induce a specific chemical stress response in microorganisms. Certain bacteria, such as the probiotic organism Lactobacillus plantarum (6,8,15), Pediococcus pentosaceus (7), and Bacillus subtilis (9,29,32), are resistant to the toxicity of phenolic acids, such as ferulic, p-coumaric, and caffeic acids. This resistance is due to the rapid induction of the padA or padC gene, which encodes a phenolic acid decarboxylase (PadA or PadC) that can rapidly degrade these antimicrobial acids into less toxic vinyl derivatives (6).…”

Transcriptional Regulation of the Vanillate Utilization Genes ( vanABK Operon) of Corynebacterium glutamicum by VanR, a PadR-Like Repressor

“…The proteins of subfamily 2 have a shorter C-terminal domain than subfamily 1 and contain 20 to 30 residues, such as LmrR from Lactococcus lactis (22) as well as Bacillus cereus PadR1 (bcPadR1) and bcPadR2 (23). Apart from their structures, physiological characteristics of the PadR, AphA, and LmrR regulators were intensively studied (21,(24)(25)(26). Intriguingly, the very first member of the PF03551 protein family, PadR, also deals with phenolic acids, albeit as a stress response regulator in B. subtilis (20,21).…”

“…PadR represses padC, encoding the phenolic acid decarboxylase in B. subtilis. Nevertheless, the exact deactivation mechanism of PadR is unknown, since phenolic acid does not directly interact with PadR (25).…”

Antibacterial Effect of Aqueous Extracts and Bioactive Chemical Compounds of <i>Coffea canephora</i> against Microorganisms Involved in Dental Caries and Periodontal Disease

“…Gury et al [32] also affirmed that phenolic acids are toxic for numerous Gram-positive bacteria under acidic condition. These authors stated that phenolic acid decarboxylase activity (PAD) in these bacteria is a detoxifying system specifically and strongly induced by these chemicals.…”