title: Para-aminobenzoic acid (PABA) synthase enhances thermotolerance of mushroom Agaricus bisporus.
abstract: Most mushrooms are thermo-sensitive to temperatures over 23°C, which greatly restricts their agricultural cultivation. Understanding mushroom's innate heat-tolerance mechanisms may facilitate genetic improvements of their thermotolerance. Agaricus bisporus strain 02 is a relatively thermotolerant mushroom strain, while strain 8213 is quite thermo-sensitive. Here, we compared their responses at proteomic level to heat treatment at 33°C. We identified 73 proteins that are differentially expressed between 02 and 8213 or induced upon heat stress in strain 02 itself, 48 of which with a known identity. Among them, 4 proteins are constitutively more highly expressed in 02 than 8213; and they can be further upregulated in response to heat stress in 02, but not in 8213. One protein is encoded by the para-aminobenzoic acid (PABA) synthase gene Pabs, which has been shown to scavenge the reactive oxygen species in vitro. Pabs mRNA and its chemical product PABA show similar heat stress induction pattern as PABA synthase protein and are more abundant in 02, indicating transcriptional level upregulation of Pabs upon heat stress. A specific inhibitor of PABA synthesis impaired thermotolerance of 02, while exogenous PABA or transgenic overexpression of 02 derived PABA synthase enhanced thermotolerance of 8213. Furthermore, compared to 8213, 02 accumulated less H2O2 but more defense-related proteins (e.g., HSPs and Chitinase) under heat stress. Together, these results demonstrate a role of PABA in enhancing mushroom thermotolerance by removing H2O2 and elevating defense-related proteins.
authors.affiliation: State Key Laboratory of Stress Cell Biology, School of Life Science, Xiamen University, Xiamen, Fujian, China.
authors.forename: Zhonglei
authors.initials: Z
authors.lastname: Lu
authors.affiliation: Key Laboratory of Biodiversity and Biogeography, Kunming Institute of Botany, Institute of Tibet Plateau Research at Kunming, Chinese Academy of Science, Kunming, Yunnan, China.
authors.forename: Xiangxiang
authors.initials: X
authors.lastname: Kong
authors.affiliation: State Key Laboratory of Stress Cell Biology, School of Life Science, Xiamen University, Xiamen, Fujian, China.
authors.forename: Zhaoming
authors.initials: Z
authors.lastname: Lu
authors.affiliation: State Key Laboratory of Stress Cell Biology, School of Life Science, Xiamen University, Xiamen, Fujian, China.
authors.forename: Meixiang
authors.initials: M
authors.lastname: Xiao
authors.affiliation: Edible Fungi Institute of Fujian Academy of Agricultural Sciences. Fuzhou, Fujian, China.
authors.forename: Meiyuan
authors.initials: M
authors.lastname: Chen
authors.affiliation: Department of Developmental and Molecular Biology, and Medicine, Albert Einstein College of Medicine, Bronx, NY, United States of America.
authors.forename: Liang
authors.initials: L
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Stress Cell Biology, School of Life Science, Xiamen University, Xiamen, Fujian, China.
authors.forename: Yuemao
authors.initials: Y
authors.lastname: Shen
authors.affiliation: Key Laboratory of Biodiversity and Biogeography, Kunming Institute of Botany, Institute of Tibet Plateau Research at Kunming, Chinese Academy of Science, Kunming, Yunnan, China.
authors.forename: Xiangyang
authors.initials: X
authors.lastname: Hu
authors.affiliation: State Key Laboratory of Stress Cell Biology, School of Life Science, Xiamen University, Xiamen, Fujian, China.
authors.forename: Siyang
authors.initials: S
authors.lastname: Song
mesh_terms: D010129:4-Aminobenzoic Acid / Q000494:pharmacology; D000222:Adaptation, Physiological / Q000187:drug effects; D000364:Agaricus / Q000187:drug effects / Q000201:enzymology* / Q000502:physiology*; D002374:Catalase / Q000378:metabolism; D002688:Chitinases / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D005656:Fungal Proteins / Q000378:metabolism; D018869:Heat-Shock Response / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism; D008954:Models, Biological; D018384:Oxidative Stress / Q000187:drug effects; D040901:Proteomics; D000077145:Sulfanilamide; D013424:Sulfanilamides / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000378:metabolism; D013696:Temperature; D000637:Transaminases / Q000378:metabolism*; D019076:Transgenes
chemical_list: D005656:Fungal Proteins; D013424:Sulfanilamides; D000077145:Sulfanilamide; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; C022309:PABA synthase; D000637:Transaminases; D002688:Chitinases; D010129:4-Aminobenzoic Acid