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Li B, Ge M, Zhang Y, Wang L, Ibrahim M, Wang Y, Sun G, Chen G. New insights into virulence mechanisms of rice pathogen Acidovorax avenae subsp. avenae strain RS-1 following exposure to ß-lactam antibiotics. Sci Rep 2016; 6:22241. [PMID: 26915352 PMCID: PMC4768089 DOI: 10.1038/srep22241] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 02/10/2016] [Indexed: 12/24/2022] Open
Abstract
Recent research has shown that pathogen virulence can be altered by exposure to antibiotics, even when the growth rate is unaffected. Investigating this phenomenon provides new insights into understanding the virulence mechanisms of bacterial pathogens. This study investigates the phenotypic and transcriptomic responses of the rice pathogenic bacterium Acidovorax avenae subsp. avenae (Aaa) strain RS-1 to ß-lactam antibiotics especially Ampicillin (Amp). Our results indicate that exposure to Amp does not influence bacterial growth and biofilm formation, but alters the virulence, colonization capacity, composition of extracellular polymeric substances and secretion of Type VI secretion system (T6SS) effector Hcp. This attenuation in virulence is linked to unique or differential expression of known virulence-associated genes based on genome-wide transcriptomic analysis. The reliability of expression data generated by RNA-Seq was verified with quantitative real-time PCR of 21 selected T6SS genes, where significant down-regulation in expression of hcp gene, corresponding to the reduction in secretion of Hcp, was observed under exposure to Amp. Hcp is highlighted as a potential target for Amp, with similar changes observed in virulence-associated phenotypes between exposure to Amp and mutation of hcp gene. In addition, Hcp secretion is reduced in knockout mutants of 4 differentially expressed T6SS genes.
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Affiliation(s)
- Bin Li
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, 310058, Hangzhou, China
| | - Mengyu Ge
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, 310058, Hangzhou, China
| | - Yang Zhang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, 310058, Hangzhou, China
| | - Li Wang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, 310058, Hangzhou, China
| | - Muhammad Ibrahim
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, 310058, Hangzhou, China.,Department of Biosciences, COMSATS Institute of Information technology Sahiwal Campus, Sahiwal, Pakistan
| | - Yanli Wang
- State Key Laboratory Breeding Base for Zhejiang Sustainable Plant Pest and Disease Control, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Guochang Sun
- State Key Laboratory Breeding Base for Zhejiang Sustainable Plant Pest and Disease Control, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Gongyou Chen
- School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai 200240, China
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O'Shields B, McArthur AG, Holowiecki A, Kamper M, Tapley J, Jenny MJ. Inhibition of endogenous MTF-1 signaling in zebrafish embryos identifies novel roles for MTF-1 in development. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1843:1818-33. [PMID: 24751692 PMCID: PMC4096078 DOI: 10.1016/j.bbamcr.2014.04.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 04/09/2014] [Accepted: 04/11/2014] [Indexed: 02/07/2023]
Abstract
The metal responsive element-binding transcription factor-1 (MTF-1) responds to changes in cellular zinc levels caused by zinc exposure or disruption of endogenous zinc homeostasis by heavy metals or oxygen-related stress. Here we report the functional characterization of a complete zebrafish MTF-1 in comparison with the previously identified isoform lacking the highly conserved cysteine-rich motif (Cys-X-Cys-Cys-X-Cys) found in all other vertebrate MTF-1 orthologs. In an effort to develop novel molecular tools, a constitutively nuclear dominant-negative MTF-1 (dnMTF-1) was generated as tool for inhibiting endogenous MTF-1 signaling. The in vivo efficacy of the dnMTF-1 was determined by microinjecting in vitro transcribed dnMTF-1 mRNA into zebrafish embryos (1-2 cell stage) followed by transcriptomic profiling using an Agilent 4x44K array on 28- and 36-hpf embryos. A total of 594 and 560 probes were identified as differentially expressed at 28hpf and 36hpf, respectively, with interesting overlaps between timepoints. The main categories of genes affected by the inhibition of MTF-1 signaling were: nuclear receptors and genes involved in stress signaling, neurogenesis, muscle development and contraction, eye development, and metal homeostasis, including novel observations in iron and heme homeostasis. Finally, we investigate both the transcriptional activator and transcriptional repressor role of MTF-1 in potential novel target genes identified by transcriptomic profiling during early zebrafish development.
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Affiliation(s)
- Britton O'Shields
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA
| | | | - Andrew Holowiecki
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA
| | - Martin Kamper
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA
| | - Jeffrey Tapley
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA
| | - Matthew J Jenny
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA.
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