Involvement of the MxtR/ErdR (CrbS/CrbR) Two-Component System in Acetate Metabolism in Pseudomonas putida KT2440.

Tania Henriquez,Heinrich Jung

doi:10.3390/microorganisms9081558

Tania Henriquez, Heinrich Jung

Open Access

https://doi.org/10.3390/microorganisms9081558

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Journal: Microorganisms	Publication Date: Jul 22, 2021
Citations: 4	License type: CC BY 4.0

Affiliation: Ludwig-Maximilians-Universität München

Abstract

MxtR/ErdR (also called CrbS/CrbR) is a two-component system previously identified as important for the utilization of acetate in Vibrio cholerae and some Pseudomonas species. In addition, evidence has been found in Pseudomonas aeruginosa for a role in regulating the synthesis and expression, respectively, of virulence factors such as siderophores and RND transporters. In this context, we investigated the physiological role of the MxtR/ErdR system in the soil bacterium Pseudomonas putida KT2440. To that end, mxtR and erdR were individually deleted and the ability of the resulting mutants to metabolize different carbon sources was analyzed in comparison to wild type. We also assessed the impact of the deletions on siderophore production, expression of mexEF-oprN (RND transporter), and the biocontrol properties of the strain. Furthermore, the MxtR/ErdR-dependent expression of putative target genes and binding of ErdR to respective promoter regions were analyzed. Our results indicated that the MxtR/ErdR system is active and essential for acetate utilization in P. putida KT2440. Expression of scpC, pp_0354, and acsA-I was stimulated by acetate, while direct interactions of ErdR with the promoter regions of the genes scpC, pp_0354, and actP-I were demonstrated by an electromobility shift assay. Finally, our results suggested that MxtR/ErdR is neither involved in regulating siderophore production nor the expression of mexEF-oprN in P. putida KT2440 under the conditions tested.

Highlights

Bacteria can colonize diverse environments, thanks to the development of different adaptive responses
Our results indicated that the MxtR/ErdR system is not involved in the regulation of pyoverdine production and mexEF-oprN expression under the conditions tested, and it does not seem to be related to the biocontrol ability of P. putida KT2440
Generated,Mutants and theirfor growth in minimal the response regulator generated, theirwas growth in minimal glucose, succinate, ethanol, or were acetate as carbonand source compared with medium the wild with type glucose, succinate, ethanol, or acetate as carbon source was compared with the wild type (WT) strain (Figure 1)

Summary

Introduction

Bacteria can colonize diverse environments, thanks to the development of different adaptive responses. Two-component systems sense changes in the environment and trigger a cellular response and adaptation. These systems consist of a sensor kinase responsible for stimulus sensing and signal transduction through autophosphorylation/phosphotransfer, and a response regulator that stimulates expression of target genes or performs other activities after phosphorylation [1]. The genome of the soil bacterium Pseudomonas putida KT2440, for example, is predicted to encode about seventytwo-component systems One of the roles of the two-components systems in Pseudomonas species is to regulate the consumption of different substrates.

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Conclusion