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The Mitochondrial Alternative Oxidase in Ustilago maydis Is Not Involved in Response to Oxidative Stress Induced by Paraquat

by Lucero Romero-Aguilar, Héctor Vázquez-Meza, Guadalupe Guerra-Sánchez, Oscar Ivan Luqueño-Bocardo and Juan Pablo Pardo

J. Fungi 2022, 8(11), 1221; https://doi.org/10.3390/jof8111221 - 19 Nov 2022

Cited by 5 | Viewed by 2120

Abstract

It has been shown that the alternative oxidase in mitochondria of fungi and plants has important functions in the response against stress conditions, although their role in some organisms is still unknown. This is the case of Ustilago maydis. There is no evidence of the participation of the U. maydis Aox1 in stressful conditions such as desiccation, high or low temperature, and low pH, among others. Therefore, in this work, we studied the role of the U. maydis Aox1 in cells exposed to oxidative stress induced by methyl viologen (paraquat). To gain insights into the role of this enzyme, we took advantage of four strains: the FB2 wild-type, a strain without the alternative oxidase (FB2aox1Δ), other with the Aox1 fused to the Gfp under the control of the original promoter (FB2aox1-Gfp), and one expressing constitutively de Aox1-Gfp (FB2Potef:aox1-Gfp). Cells were incubated for various times in the presence of 1 mM paraquat and growth, replicative capacities, mitochondrial respiratory activity, Aox1 capacity, and the activities of several antioxidant enzymes (catalase, glutathione peroxidase, glutathione reductase, and superoxide dismutase) were assayed. The results show that (1) the response of U. maydis against oxidative stress was the same in the presence or absence of the Aox1; (2) the activities of the antioxidant enzymes remained constant despite the oxidative stress; and (3) there was a decrease in the GSH/GSSG ratio in U. maydis cells incubated with paraquat. Full article

(This article belongs to the Special Issue Fungal Metabolism in Filamentous Fungi)

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15 pages, 1630 KiB

Open AccessArticle

Lower Temperature Cultures Enlarge the Effects of Vitreoscilla Hemoglobin Expression on Recombinant Pichia pastoris

by Jyh-Ming Wu, Shin-Yao Wang and Wei-Chang Fu

Int. J. Mol. Sci. 2012, 13(10), 13212-13226; https://doi.org/10.3390/ijms131013212 - 15 Oct 2012

Cited by 19 | Viewed by 7076

Abstract

An heterologous expression of Vitreoscilla hemoglobin (VHb) for improving cell growth and recombinant protein production has been successfully demonstrated in various hosts, including Pichia pastoris. Lower temperature cultures can enhance target protein production in some studies of P. pastoris. In this study, the strategy of combining heterologous VHb expression and lower temperature cultures in P. pastoris showed that final cell density and viability of VHb⁺ strain at 23 °C were higher than that at 30 °C. In addition, the effects of VHb expression on recombinant β-galactosidase production and oxygen uptake rate were also higher at 23 °C than at 30 °C. Consequently, lower temperature cultures can enlarge VHb effectiveness on cell performance of P. pastoris. This is because VHb activity obtained at 23 °C cultures was twofold higher than that at 30 °C cultures, due to a different heme production. This strategy makes P. pastoris an excellent expression host particularly suitable for increasing the yields of the low-stability and aggregation-prone recombinant proteins. Full article

(This article belongs to the Section Biochemistry)

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