Proteomic Analyses Reveal the Mechanism of Dunaliella salina Ds-26-16 Gene Enhancing Salt Tolerance in Escherichia coli

PLOS ONE, Dec 2019

We previously screened the novel gene Ds-26-16 from a 4 M salt-stressed Dunaliella salina cDNA library and discovered that this gene conferred salt tolerance to broad-spectrum organisms, including E. coli (Escherichia coli), Haematococcus pluvialis and tobacco. To determine the mechanism of this gene conferring salt tolerance, we studied the proteome of E. coli overexpressing the full-length cDNA of Ds-26-16 using the iTRAQ (isobaric tags for relative and absolute quantification) approach. A total of 1,610 proteins were identified, which comprised 39.4% of the whole proteome. Of the 559 differential proteins, 259 were up-regulated and 300 were down-regulated. GO (gene ontology) and KEGG (Kyoto encyclopedia of genes and genomes) enrichment analyses identified 202 major proteins, including those involved in amino acid and organic acid metabolism, energy metabolism, carbon metabolism, ROS (reactive oxygen species) scavenging, membrane proteins and ABC (ATP binding cassette) transporters, and peptidoglycan synthesis, as well as 5 up-regulated transcription factors. Our iTRAQ data suggest that Ds-26-16 up-regulates the transcription factors in E. coli to enhance salt resistance through osmotic balance, energy metabolism, and oxidative stress protection. Changes in the proteome were also observed in E. coli overexpressing the ORF (open reading frame) of Ds-26-16. Furthermore, pH, nitric oxide and glycerol content analyses indicated that Ds-26-16 overexpression increases nitric oxide content but has no effect on glycerol content, thus confirming that enhanced nitric oxide synthesis via lower intercellular pH was one of the mechanisms by which Ds-26-16 confers salt tolerance to E. coli.

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Proteomic Analyses Reveal the Mechanism of Dunaliella salina Ds-26-16 Gene Enhancing Salt Tolerance in Escherichia coli

May Proteomic Analyses Reveal the Mechanism of Dunaliella salina Ds-26-16 Gene Enhancing Salt Tolerance in Escherichia coli Yanlong Wang 0 1 Bin Hu 0 1 Shipeng Du 0 1 Shan Gao 1 Xiwen Chen 1 Defu Chen 0 1 0 Department of Genetics and Cell Biology, College of Life Sciences, Nankai University , Tianjin, 300071, China , 2 Department of Biochemistry and Molecular Biology, College of Life Sciences, Nankai University , Tianjin, 300071, China , 3 Department of Zoology and Developmental Biology, College of Life Sciences, Nankai University , Tianjin, 300071 , China 1 Editor: Shaojun Dai, Northeast Forestry University , CHINA We previously screened the novel gene Ds-26-16 from a 4 M salt-stressed Dunaliella salina cDNA library and discovered that this gene conferred salt tolerance to broad-spectrum organisms, including E. coli (Escherichia coli), Haematococcus pluvialis and tobacco. To determine the mechanism of this gene conferring salt tolerance, we studied the proteome of E. coli overexpressing the full-length cDNA of Ds-26-16 using the iTRAQ (isobaric tags for relative and absolute quantification) approach. A total of 1,610 proteins were identified, which comprised 39.4% of the whole proteome. Of the 559 differential proteins, 259 were up-regulated and 300 were down-regulated. GO (gene ontology) and KEGG (Kyoto encyclopedia of genes and genomes) enrichment analyses identified 202 major proteins, including those involved in amino acid and organic acid metabolism, energy metabolism, carbon metabolism, ROS (reactive oxygen species) scavenging, membrane proteins and ABC (ATP binding cassette) transporters, and peptidoglycan synthesis, as well as 5 up-regulated transcription factors. Our iTRAQ data suggest that Ds-26-16 up-regulates the transcription factors in E. coli to enhance salt resistance through osmotic balance, energy metabolism, and oxidative stress protection. Changes in the proteome were also observed in E. coli overexpressing the ORF (open reading frame) of Ds-26-16. Furthermore, pH, nitric oxide and glycerol content analyses indicated that Ds-26-16 overexpression increases nitric oxide content but has no effect on glycerol content, thus confirming that enhanced nitric oxide synthesis via lower intercellular pH was one of the mechanisms by which Ds-26-16 confers salt tolerance to E. coli. - OPEN ACCESS Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Funding: This work was supported by the grant of the National Natural Science Foundation of China (no. 31570769), the Key Program of the Natural Science Foundation of Tianjin (no. 14JCZDJC34100, 12JCZDJC22900) and the 111 Project (no. B08011). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. Introduction Soil salinization is one of the major factors that limit the growth and distribution of organisms. Currently, the worldwide saline soil area is greater than 6% of the total land area [ 1 ] and is projected to increase to 50% by the year 2050 [ 2 ]. High salinity can lead to ion imbalance and hyperosmotic and oxidative stress, which can result in plant growth retardation, wilting or death [ 3 ]. Therefore, identifying novel salt-tolerant genes and elucidating their molecular mechanisms in conferring salt tolerance will provide a basis for effective engineering strategies to enhance salt tolerance to organisms. This goal is of extraordinary significance for the improvement and utilization of salinized soil. Plant responses to salt stress have been extensively studied using morphological, physiological and ecological methods [ 4 ]. A number of important genes related to salt stress have been cloned, and their functions have been confirmed by genetic transformation [ 5–8 ]. However, plant response to salt stress is a dynamic, multi-level and holistic process involving a large number of genes and multiple signaling and metabolic pathways. High-throughput transcriptomic and proteomic assays are powerful in identifying genes implicated in the biological processes of various organisms. Transcriptomic analysis of the rosettes and roots of Thellungiella showed that 125 ESTs (expressed sequence tags) and 103 unigenes might be related to salt stress and include stress proteins, antioxidant enzymes, transporters, ion homeostasis, signaling components, and transcriptional regulators [9]. Transcriptomics of the salt-tolerant wheat SR3 identified the SR3 allele of sro1, a gene encoding a PARP [poly (ADP-ribose) polymerase] domain protein, which underpins both seedling vigor and abiotic stress tolerance by modulating redox homeostasis and maintaining genomic stability [ 10 ]. Over-expression of Ta-sro1 in wheat and in Arabidopsis enhanced the activity of NADPH (nicotinamide adenine dinucleotide phosphate) oxidase, NAD(P)H dehydrogenase, ascorb (...truncated)


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Yanlong Wang, Bin Hu, Shipeng Du, Shan Gao, Xiwen Chen, Defu Chen. Proteomic Analyses Reveal the Mechanism of Dunaliella salina Ds-26-16 Gene Enhancing Salt Tolerance in Escherichia coli, PLOS ONE, 2016, Volume 11, Issue 5, DOI: 10.1371/journal.pone.0153640