A magnesium transporter is involved in the cesium ion resistance of the high-concentration cesium ion-resistant bacterium Microbacterium sp. TS-1

Yoshiki Ishida; Takahiro Koretsune; Eri Ishiuchi; Miyu Teshima; Masahiro Ito

doi:10.3389/fmicb.2023.1136514

A magnesium transporter is involved in the cesium ion resistance of the high-concentration cesium ion-resistant bacterium Microbacterium sp. TS-1

Front Microbiol. 2023 Feb 23:14:1136514. doi: 10.3389/fmicb.2023.1136514. eCollection 2023.

Authors

Yoshiki Ishida¹, Takahiro Koretsune¹, Eri Ishiuchi², Miyu Teshima², Masahiro Ito^{1

2

3

4}

Affiliations

¹ Graduate School of Life Sciences, Toyo University, Oura-gun, Gunma, Japan.
² Faculty of Life Sciences, Toyo University, Oura-gun, Gunma, Japan.
³ Bio-Nano Electronics Research Center, Toyo University, Kawagoe, Saitama, Japan.
⁴ Bio-Resilience Research Project (BRRP), Toyo University, Oura-gun, Gunma, Japan.

Abstract

Cesium ion (Cs⁺) resistance has been reported in bacteria but is poorly understood as reports on Cs⁺-resistant bacteria have been limited. We previously reported a novel Cs⁺/H⁺ antiporter CshA implicated in Cs⁺-resistance in Microbacterium sp. TS-1. The present study used the same screening method to isolate novel Cs⁺-sensitive mutants and their revertants from TS-1. A comparative mutation site analysis using whole-genome sequencing revealed that MTS1_03028 encodes the Mg²⁺ transporter MgtE and is a candidate Cs⁺ resistance-related gene. We performed a bioinformatic analysis of MTS1_03028 and complementation experiments on Cs⁺ resistance in the TS-1 MTS1_03028 mutants Mut5 and Mut7 as well as Escherichia coli expressing MTS1_03028 in the presence of Mg²⁺. We established the role of MgtE in Cs⁺ resistance through a functional analysis of TS-1. Enhancing Mg²⁺ transport by expression of MTS_03028 conferred increased Cs⁺ resistance. When this strain was exposed to Cs⁺ concentrations exceeding 200 mM, CshA consistently lowered the intracellular Cs⁺ concentration. To our knowledge, the present study is the first to clarify the mechanism of Cs⁺ resistance in certain bacteria. The study findings offer important insights into the mechanism of bacterial resistance to excess Cs⁺ in the environment, suggesting the potential for bioremediation in high Cs-contaminated areas.

Keywords: Cs+/H+ antiporter; Microbacterium; alkaliphile bacteria; alkaliphiles; cesium-resistant microorganism; jumping spider; magnesium transporter.