通讯机构：
[Aiping Wu] E;[Naili Zhang] T;The Key Laboratory for Silviculture and Conservation of Ministry of Education, Beijing Forestry University , Beijing 100083 , China<&wdkj&>Ecology Department, College of Resources and Environment, Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, Hunan Agricultural University , Changsha 410128, Hunan , China
关键词：
sulfuric and nitric acid rain;mycorrhizal efficiency;Zelkova serrata;antioxidant enzymes;photosynthetic capability;soluble protein
摘要：
Acid rain (AR), which occurs frequently in southern China, negatively affects the growth of subtropical tree species. Arbuscular mycorrhizal fungi (AMF) mitigate the detrimental effects induced by AR. However, the mechanisms by which AMF protect Zelkova serrata, an economically important tree species in southern China, from AR stress remain unclear. We conducted a greenhouse experiment in which Z. serrata plants were inoculated with AMF species Rhizophagus intraradices and Diversispora versiformis, either alone or as a mixed culture, or with a sterilized inoculum (negative control). The plants were subjected to three levels of simulated sulfuric AR and nitric AR (pH 2.5, 4.0 and 5.6) to examine any interactive effects on growth, photosynthetic capabilities, antioxidant enzymes, osmotic adjustment and soil enzymes. AR significantly decreased dry weight, chlorophyll content, net photosynthetic rate and soluble protein (SP) of non-mycorrhizal plants. Mycorrhizal inoculation, especially a combination of R. intraradices and D. versiformis, notably improved dry weight, photosynthetic capabilities, catalase, peroxidase, superoxide dismutase, SP and root acid phosphatase activity of Z. serrata under harsh AR stress. Moreover, the benefits from AMF symbionts depended on the identity of AM fungal species and the gradient of AR stress. Our results indicate that AM fungi protect Z. serrata against AR stress by synchronously activating photosynthetic ability, antioxidant enzymes and osmolyte accumulation. These findings suggest that a combination of R. intraradices and D. versiformis may be a preferable choice for culturing Z. serrata in southern China.
作者机构：
[Rui Wang] School of Life Sciences and Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China;[Chang-Zhu Li] State Key Laboratory of Utilization of Woody Oil Resource, Hunan Academy of Forestry, Changsha 410004, China;[Wen-Wen Cui] Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China;[Xue Zhang; Peng-Cheng Yu; Di Liu; Yun-Tao Lei; Xing-Hua Li; Wen-Hui Wang] Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China;[Ying-Zhe Fan] Putuo Hospital, Shanghai University of Chinese Traditional Medicine, Shanghai 200062, China
通讯机构：
[Rui Wang] S;[Ying-Zhe Fan] P;[Ye Yu] D;Putuo Hospital, Shanghai University of Chinese Traditional Medicine, Shanghai 200062, China<&wdkj&>Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China<&wdkj&>Department of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China<&wdkj&>School of Life Sciences and Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China
关键词：
Ligand-gated ion channels;TRPV1;Allostery;Voltage-clamp fluorometry;Vanilloid agonist
摘要：
Transient receptor potential vanilloid 1 (TRPV1) channel plays an important role in a wide range of physiological and pathological processes, and a comprehensive understanding of TRPV1 gating will create opportunities for therapeutic intervention. Recent incredible advances in cryo-electron microscopy (cryo-EM) have yielded high-resolution structures of all TRPV subtypes (TRPV1–6) and all of them share highly conserved six transmembrane (TM) domains (S1–S6). As revealed by the open structures of TRPV1 in the presence of a bound vanilloid agonist (capsaicin or resiniferatoxin), TM helices S1 to S4 form a bundle that remains quiescent during channel activation, highlighting differences in the gating mechanism of TRPV1 and voltage-gated ion channels. Here, however, we argue that the structural dynamics rather than quiescence of S1–S4 domains is necessary for capsaicin-mediated activation of TRPV1. Using fluorescent unnatural amino acid (flUAA) incorporation and voltage-clamp fluorometry (VCF) analysis, we directly observed allostery of the S1–S4 bundle upon capsaicin binding. Covalent occupation of VCF-identified sites, single-channel recording, cell apoptosis analysis, and exploration of the role of PSFL828, a novel non-vanilloid agonist we identified, have collectively confirmed the essential role of this coordinated S1–S4 motility in capsaicin-mediated activation of TRPV1. This study concludes that, in contrast to cryo-EM structural studies, vanilloid agonists are also required for S1–S4 movement during TRPV1 activation. Redefining the gating process of vanilloid agonists and the discovery of new non-vanilloid agonists will allow the evaluation of new strategies aimed at the development of TRPV1 modulators.
通讯机构：
[Jiamu Du; Jiamu Du Jiamu Du Jiamu Du] K;[Mingguang Lei; Mingguang Lei Mingguang Lei Mingguang Lei] S;Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055 China<&wdkj&>Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 201602 China
摘要：
DNA methylation, a conserved epigenetic mark, is critical for tuning temporal and spatial gene expression. The Arabidopsis thaliana DNA glycosylase/lyase REPRESSOR OF SILENCING 1 (ROS1) initiates active DNA demethylation and is required to prevent DNA hypermethylation at thousands of genomic loci. However, how ROS1 is recruited to specific loci is not well understood. Here, we report the discovery of Arabidopsis AGENET Domain Containing Protein 3 (AGDP3) as a cellular factor that is required to prevent gene silencing and DNA hypermethylation. AGDP3 binds to H3K9me2 marks in its target DNA via its AGD12 cassette. Analysis of the crystal structure of the AGD12 cassette of AGDP3 in complex with an H3K9me2 peptide revealed that dimethylated H3K9 and unmodified H3K4 are specifically anchored into two different surface pockets. A histidine residue located in the methyllysine binding aromatic cage provides AGDP3 with pH-dependent H3K9me2 binding capacity. Our results uncover a molecular mechanism for the regulation of DNA demethylation by the gene silencing mark H3K9me2.
