Elevated intracellular cyclic‐di‐GMP level in Shewanella oneidensis increases expression of c‐type cytochromes

Kiat Ng, C., Xu, J. , Cai, Z., Yang, L., Thompson, I. P., Huang, W. E. and Cao, B. (2020) Elevated intracellular cyclic‐di‐GMP level in Shewanella oneidensis increases expression of c‐type cytochromes. Microbial Biotechnology, 13(6), pp. 1904-1916. (doi: 10.1111/1751-7915.13636) (PMID:32729223) (PMCID:PMC7533324)

Abstract

Summary. Electrochemically active biofilms are capable of exchanging electrons with solid electron acceptors and have many energy and environmental applications such as bioelectricity generation and environmental remediation. The performance of electrochemically active biofilms is usually dependent on c-type cytochromes, while biofilm development is controlled by a signal cascade mediated by the intracellular secondary messenger bis-(3ʹ-5ʹ) cyclic dimeric guanosine monophosphate (c-di-GMP). However, it is unclear whether there are any links between the c-di-GMP regulatory system and the expression of c-type cytochromes. In this study, we constructed a S. oneidensis MR-1 strain with a higher cytoplasmic c-di-GMP level by constitutively expressing a c-di-GMP synthase and it exhibited expected c-di-GMP-influenced traits, such as lowered motility and increased biofilm formation. Compared to MR-1 wild-type strain, the high c-di-GMP strain had a higher Fe(III) reduction rate (21.58 vs 11.88 pM of Fe(III)/h cell) and greater expression of genes that code for the proteins involved in the Mtr pathway, including CymA, MtrA, MtrB, MtrC and OmcA. Furthermore, single-cell Raman microspectroscopy (SCRM) revealed a great increase of c-type cytochromes in the high c-di-GMP strain as compared to MR-1 wild-type strain. Our results reveal for the first time that the c-di-GMP regulation system indirectly or directly positively regulates the expression of cytochromes involved in the extracellular electron transport (EET) in S. oneidensis, which would help to understand the regulatory mechanism of c-di-GMP on electricity production in bacteria.

• Item Type: Articles
• Additional Information: B. Cao acknowledges financial support from the Ministry of Education (MOE) Academic Research Fund (AcRF) Tier 2 Grant(MOE2017-T2-2-042) and the National Research Foundation and MOE Singapore under its Research Centre of Excellence Programme, Singapore Centre for Environmental Life Sciences Engi-neering (SCELSE) (M4330005.C70), Nanyang Technological University, Singapore. W. E. Huang acknowledges financial and instrumentational support from EPSRC (Grants EP/M002403/1 and EP/M02833X/1) and NERC (Grant NE/M002934/1). C. K. Ng acknowledges financial support from Commonwealth Scholarship Commission in the form of Commonwealth Rutherford Fellowship (SGRF-2017-471).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Xu, Dr Jiabao
• Authors: Kiat Ng, C., Xu, J., Cai, Z., Yang, L., Thompson, I. P., Huang, W. E., and Cao, B.
• College/School: College of Science and Engineering > School of Engineering > Biomedical Engineering
• Journal Name: Microbial Biotechnology
• Publisher: Applied Microbiology International
• ISSN: 1751-7915
• ISSN (Online): 1751-7915
• Published Online: 30 July 2020
• Copyright Holders: Copyright © The Author(s) 2020
• First Published: First published in Microbial Biotechnology 13(6):1904-1916
• Publisher Policy: Reproduced under a creative commons licence