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- Non-Mitochondrial Aconitase-2 Mediates the Transcription of Nuclear-Encoded Electron Transport Chain Genes in Fission Yeast
- Ho-Jung Kim, Soo-Yeon Cho, Soo-Jin Jung, Yong-Jun Cho, Jung-Hye Roe, Kyoung-Dong Kim
- J. Microbiol. 2024;62(8):639-648. Published online June 25, 2024
- DOI: https://doi.org/10.1007/s12275-024-00147-8
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Abstract
- Aconitase-2 (Aco2) is present in the mitochondria, cytosol, and nucleus of fission yeast. To explore its function beyond the well-known role in the mitochondrial tricarboxylic acid (TCA) cycle, we conducted genome-wide profiling using the aco2ΔNLS mutant, which lacks a nuclear localization signal (NLS). The RNA sequencing (RNA-seq) data showed a general downregulation of electron transport chain (ETC) genes in the aco2ΔNLS mutant, except for those in the complex II, leading to a growth defect in respiratory-prone media. Complementation analysis with non-catalytic Aco2 [aco2ΔNLS + aco2(3CS)], where three cysteines were substituted with serine, restored normal growth and typical ETC gene expression. This suggests that Aco2's catalytic activity is not essential for its role in ETC gene regulation. Our mRNA decay assay indicated that the decrease in ETC gene expression was due to transcriptional regulation rather than changes in mRNA stability. Additionally, we investigated the Php complex's role in ETC gene regulation and found that ETC genes, except those within complex II, were downregulated in php3Δ and php5Δ strains, similar to the aco2ΔNLS mutant. These findings highlight a novel role for nuclear aconitase in ETC gene regulation and suggest a potential connection between the Php complex and Aco2.
Research Support, Non-U.S. Gov't
- Involvement of Alternative Oxidase in the Regulation of Sensitivity of Sclerotinia sclerotiorum to the Fungicides Azoxystrobin and Procymidone
- Ting Xu , Ya-Ting Wang , Wu-Sheng Liang , Fei Yao , Yong-Hong Li , Dian-Rong Li , Hao Wang , Zheng-Yi Wang
- J. Microbiol. 2013;51(3):352-358. Published online April 26, 2013
- DOI: https://doi.org/10.1007/s12275-013-2534-x
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- 29 Scopus
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Abstract
- Sclerotinia sclerotiorum is a filamentous fungal pathogen that can infect many economically important crops and vegetables. Alternative oxidase is the terminal oxidase of the alternative respiratory pathway in fungal mitochondria. The function of alternative oxidase was investigated in the regulation of sensitivity of S. sclerotiorum to two commercial fungicides, azoxystrobin and procymidone which have different fungitoxic mechanisms. Two isolates of S. sclerotiorum were sensitive to both fungicides. Application of salicylhydroxamic acid, a specific inhibitor of alternative oxidase, significantly increased the values of effective concentration causing 50% mycelial growth inhibition (EC50) of azoxystrobin to both S. sclerotiorum isolates, whereas notably decreased the EC50 values of procymidone. In mycelial respiration assay azoxystrobin displayed immediate inhibitory effect on cytochrome pathway capacity, but had no immediate effect on alternative pathway capacity. In contrast, procymidone showed no immediate impact on capacities of both cytochrome and alternative pathways in the mycelia. However, alternative oxidase encoding gene (aox) transcript and protein levels, alternative respiration pathway capacity of the mycelia were obviously increased by pre-treatment for 24 h with both azoxystrobin and procymidone. These results indicate that alternative oxidase was involved in the regulation of sensitivity of S. sclerotiorum to the fungicides azoxystrobin and procymidone, and that both fungicides could affect aox gene expression and the alternative respiration pathway capacity development in mycelia of this fungal pathogen.
- Growth Properties of the Iron-reducing Bacteria, Shewanella putrefaciens IR-1 and MR-1 Coupling to Reduction of Fe(III) to Fe(II)
- Doo Hyun Park , Byung Hong Kim
- J. Microbiol. 2001;39(4):273-278.
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Abstract
- Shewanella putrefaciens IR-1 and MR-1 were cultivated by using various combinations of electron donor-acceptor, lactate-Fe(III), lactate-nitrate, pyruvate-Fe(III), pyruvate-nitrate, H_2 -acetate-Fe(III) and H_2 -acetate-nitrate. Both strains grew fermentatively on pyruvate but not on lactate without an electron acceptor. In culture with Fe(III), both strains grew on pyruvate and lactate but not on H_2 -acetate-CO_2 . In cultivation with nitrate, both strains grew on pyruvate, lactate and on H_2 -acetate-CO_2 . The growth yields of IR-1 on pyruvate, pyruvate-Fe(III) and lactate-Fe(III) were about 3.4, 3.5, and 3.6 (g cell/M substrate), respectively, but the yields on lactate-nitrate, pyruvate-nitrate and H_2 -acetate-CO_2 ?trate were about 6.8, 5.9, and 9.4 (g cell/M substrate), respectively. From the growth properties of both strains on media with Fe(III) as an electron acceptor, the bacterial growth was confirmed not to be increased by addition of Fe(III) as an electron acceptor to the growth medium, which indicates a possibility that the dissimilatory reduction of Fe(III) to Fe(II) may not be coupled to free energy production.
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