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Solid and Solution Structural Studies of Dimeric and Tetrameric Molybdenum(VI) malate Complexes

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Chinese Journal of Structural Chemistry 2008年第8期27卷 919-926页

作者：张荣华周朝晖万惠霖 Department of Chemistry College of Chemistry and Chemical Engineering State Key Laboratory of Physical Chemistry of Solid Surfaces Xiamen UniversityXiamen 361005 China

Reactions of potassium molybdate with racemic malic acid （H3mal = C4H6O5） result in the isolation of two mesomeric molybdenum malate complexes K8[（MoO2）2O（R-mal）2][（MoO2）2O（Smal）2]-4H2O 1 and （Him）2K6[（MoO2）4O3（R-mal）2][（MoOE）4O3（S-mal）2]-8H2O 2. Complex 1 belongs to the monoclinic system, space group C2/c with a = 14.8637（3）, b = 6.9544（1）, c = 19.6783（5）A, β = 100.081（2）°, V = 2002.70（7） A^3, Mr = 1452.88, Z = 2, F（000） = 1416, T = 173 K, Dc = 2.409 g/cm3, fl（MoKa＇） = 2.167, R = 0.0283 and wR = 0.0733.2 is of triclinic system, space group P1^- with a = 8.7707（2）, b = 9.3310（3）, c = 17.9093（7）A, α= 83.781（3）, β = 85.626（2）, y= 84.822（2）°, V = 1447.84（8）A^3, Mr = 2160.68, Z = 1, F（000） = 1048, T = 173 K, Dc = 2.478 g/cm^3,μ（MoKα） = 2.230, R = 0.0234 and wR = 0.0584.1 is the first isolated dinuclear molybdenum（VI） malato complex in 1：1 molar ratio. The molybdenum atoms in the two complexes are six-coordinated in an approximately octahedral geometry. Two malates coordinate tridentately with the Mo atom via their α-alkoxy, α-carboxy and α-carboxy groups in 1 and 2. β-Carboxy group in 2 further links with the other two Mo atoms to give a tetrameric unit. The solution ^1H and ^13C NMR spectra indicate that dimeric malate molybdenum in 1 dissociates partly in solution and exists in an equilibrium with tetrameric species, while 2 is stable and retains its tetrameric structure without any dissociation.

关键词： molybdate（VI） malate nitrogenase crystal structure NMR

BTB-BACK-TAZ domain protein MdBT2-mediated MdMYB73 ubiquitination negatively regulates malate accumulation and vacuolar acidification in apple

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Horticulture Research 2020年第1期7卷 827-838页

作者： Quan-Yan Zhang Kai-Di Gu Jia-Hui Wang Jian-Qiang Yu Xiao-Fei Wang Shuai Zhang Chun-Xiang You Da-Gang Hu Yu-Jin Hao National Key Laboratory of Crop Biology Shandong Collaborative Innovation Center of Fruit&Vegetable Quality and Efficient ProductionCollege of Horticulture Science and EngineeringShandong Agricultural UniversityTai-AnShandong 271018China College of Chemistry and Material Science Shandong Agricultural UniversityTai-AnShandong 271018China

As an important primary metabolite,malate plays a key role in regulating osmotic pressure,pH homeostasis,stress tolerance,and fruit quality of apple.The R2R3-MYB transcription factor(TF)MdMYB73 was identified as a protein that plays a critical role in determining malate accumulation and vacuolar acidification by directly regulating the transcription of aluminum-activated malate transporter 9(MdALMT9),vacuolar ATPase subunit A(MdVHA-A),and vacuolar pyrophosphatase 1(MdVHP1)in apple.In addition,the bHLH TF MdCIbHLH1 interacts with MdMYB73 and enhances the transcriptional activity of MdMYB73.Our previous studies demonstrated that the BTB-BACK-TAZ domain protein MdBT2 can degrade MdCIbHLH1 to influence malate accumulation and vacuolar acidification.However,the potential upstream regulators of MdMYB73 are currently unknown.In this study,we found that MdBT2 directly interacts with and degrades MdMYB73 through the ubiquitin/26S proteasome pathway to regulate malate accumulation and vacuolar acidification.A series of functional assays with apple calli and fruit showed that MdBT2 controls malate accumulation and vacuolar acidification in an MdMYB73-dependent manner.Overall,our findings shed light on the mechanism by which the BTB-BACK-TAZ domain protein MdBT2 regulates malate accumulation and vacuolar acidification by targeting MdMYB73 and MdCIbHLH1 for ubiquitination in apple.This information may help guide traditional breeding programs and fruit tree molecular breeding,and lead to improvements in fruit quality and stress tolerance.

关键词： malate ubiquitin homeostasis

Different Effects of malate on the Activities of Photosystem II in Detached Leaves of Maize and Tobacco

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American Journal of Plant Sciences 2015年第11期6卷 1734-1741页

作者： Zhenhai Cui Ao Zhang Ziling Hu Lijun Zhang Jinjuan Fan Yanshu Zhu Kai Hu Yanye Ruan Yixin Guan Biological Science and Technology College Shenyang Agricultural University Shenyang China Liaoning Province Research Center of Plant Genetic Engineering Technology Shenyang China Northeast Institute of Geography and Agroecology Chinese Academy of Sciences Changchun China

malate is the first stable product after CO2 is fixed in NADP-dependent malic enzyme (NADP-ME) type of C4 plants, which transfers CO2 and the reducing equivalent from mesophyll cell (MC) to vascular bundle sheath cell (BSC) chloroplasts and affects the redox state of BSC. The aim of this experiment is to investigate the effect of exogenous malate on the activity of photosystem II (PS II) in C4 and C3 plants. The leaf discs from the 5th fully expanded leaves of maize (NADP-ME type C4 plants) and the 10th fully expanded leaves of tobacco (C3 plants) were treated with malate of 50, 100 μM and the chlorophyll fluorescence parameters were measured. malate treatments decreased the photochemical reaction efficiency (FV/FM) in maize leaves, as a result of rising in initial fluorescence (FO) and decreasing in maximal fluorescence (FM). The number of active PS II reaction center (RC) per excited cross section (RC/CS) declined in malate-treated maize, suggesting that malate inactivated PS II RC. malate treatments also increased Wk, representing the severity of oxygen-evolving complex (OEC) damage, and decreased the rate of photosynthetic oxygen evolution. We conclude that exogenous malate regulates the activity and structure of PS II in C4 plant maize. No significant changes in the activity of PS II were observed in malate-treated C3 plant tobacco. It is suggested that the short term malate treatment will inhibit PS II of leaves which have C4 anatomy and C4 enzymes.

关键词： malate Photosystem II Chlorophyll Fluorescence Maize Tobacco

Structural Basis for the Interaction of 14-3-3<i>β</i>with Tricarboxylic Acid Cycle Intermediate malate

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Journal of Biosciences and Medicines 2017年第8期5卷 36-47页

作者： Zhiqiang Hou Lijing Su Xiaoyan Liu Department of Biophysics Dallas USA Center for Alzheimer and Neurodegenerative Disease Dallas USA Center for the Genetics of Host Defense Dallas USA Department of Microbiology University of Texas Southwestern Medical Center Dallas USA

The protein family of 14-3-3(s) has risen to a position of higher importance as an adaptor protein in cell biology. The seven highly conserved human 14-3-3 proteins coordinate diverse cellular processes including apoptosis, DNA damage response, protein trafficking, and others. In liver hepatocytes, 14-3-3β binds to Ser196-phosphorilated glucose-responsive carbohydrate response element-binding protein (ChREBP) to inhibit converting excess carbohydrate to fat by regulating the nuclear/cytosol trafficking of ChREBP. Here, we report X-ray crystal structures of homodimeric mammalian 14-3-3β in its apo, malate-bound forms. The determined apo structure was captured with one monomer in the closed state, whereas the other one had an open conformation. Strikingly, 14-3-3β binds malate dynamically with a double-closed state, which is distinct from all previously characterized 14-3-3(s) and target ligand-binding modes. malate docks into a first-time observed cofactor pocket located at the concaved interface of 14-3-3β helices α2, α3, α4 through mainly electrostatic and hydrogen interactions. Such a Tricarboxylic Acid Cycle intermediate malate bond model might offer a new approach to further analyze insulin-independent 14-3-3/ChREBP pathway of de novo fat synthesis in the liver.

关键词： Crystal Structure 14-3-3 Protein ChREBP Transcription Activation malate Malic Acid

The pH of the Apoplast： Dynamic Factor with =unctional Impact Under Stress

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Molecular Plant 2017年第11期10卷 1371-1386页

作者： Christoph-Martin Geilfus Division of Controlled Environment Horticulture Faculty of Life Sciences Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences Humboldt-University of Berlin Albrecht-Thaer-Weg 1 14195 Berlin Germany

The apoplast is an interconnected compartment with a thin water-film that alkalinizes under stress. This systemic pH increase may be a secondary effect without functional implications, arising from ion movements or proton-pump regulations. On the other hand, there are increasing indications that it is part of a mechanism to withstand stress. Regardless of this controversy, alkalinization of the apoplast has received little attention. The apoplastic pH （PHapo） increases not only during plant-pathogen interactions but also in response to salinity or drought. Not much is known about the mechanisms that cause the leaf apoplast to alkalinize, nor whether, and if so, how functional impact is conveyed. Controversial explanations have been given, and the unusual complexity of pHapo regulation is considered as the primary reason behind this lack of knowledge. A gathering of scattered information revealed that changes in PHapo convey functionality by regulating stomatal aperture via the effects exerted on abscisic acid. Moreover, apoplastic alkalinization may regulate growth under stress, whereas this needs to be verified. In this review, a comprehensive survey about several physiological mechanisms that alkalize the apoplast under stress is given, and the suitability of apoplastic alkalinization as transducing element for the transmission of sensory information is discussed.

关键词： apoplastic fluid alkalinization abscisic acid PM-H^＋-ATPase S-Type anion channel malate

Mitochondrial malic enzyme 2 promotes breast cancer metastasis via stabilizing HIF-1α under hypoxia

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Chinese Journal of Cancer Research 2021年第3期33卷 308-322页

作者： Duo You Danfeng Du Xueke Zhao Xinmin Li Minfeng Ying Xun Hu Cancer Institute(Key Laboratory for Cancer Intervention and Prevention China National Ministry of EducationZhejiang Provincial Key Laboratory of Molecular Biology in Medical Sciences)The Second Affiliated HospitalZhejiang University School of MedicineHangzhou 310000China State Key Laboratory of Esophageal Cancer Prevention&Treatment and Henan Key Laboratory of Esophageal Cancer Research of the First Affiliated Hospital Zhengzhou UniversityZhengzhou 450000China Department of Pathology Women and Infants Hospital of ZhengzhouZhengzhou 450000China

Objective: α-ketoglutarate(α-KG) is the substrate to hydroxylate collagen and hypoxia-inducible factor-1α(HIF-1α), which are important for cancer metastasis. Previous studies have shown that the upregulation of collagen prolyl 4-hydroxylase in breast cancer cells stabilizes the expression of HIF-1α by depleting α-KG levels. We hypothesized that mitochondrial malic enzyme 2(ME2) might also affect HIF-1α expression via modulating α-KG levels in breast cancer cells.Methods: We evaluated ME2 protein expression in 100 breast cancer patients using immunohistochemistry and correlated with clinicopathological indicators. The effect of ME2 knockout on cancer metastasis was evaluated using an orthotopic breast cancer model. The effect of ME2 knockout or knockdown on the levels of α-KG and HIF-1α proteins in breast cancer cell lines was determined both in vitro and in vivo.Results: ME2 was found to be upregulated in the human breast cancerous tissues compared with the matched precancerous tissues(Pmalate and α-KG exerted similar effect on HIF-1α in breast cancer cells to ME2 knockout or knockdown. Additionally,treatment with malate significantly decreased 4 T1 breast cancer lung metastasis. ME2 expression was associated with HIF-1α levels in human breast cancer samples(P=0.008).Conclusions: Our results pro

关键词： Malic enzyme 2 breast cancer metastasis malate α-ketoglutarate hypoxia-inducible factor-1α

Alterations in enterocyte mitochondrial respiratory function and enzyme activities in gastrointestinal dysfunction following brain injury

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World Journal of Gastroenterology 2014年第28期20卷 9585-9591页

作者： Ke-Jun Zhu Hong Huang Hui Chu Hang Yu Shi-Ming Zhang Department of Neurosurgery the First Affiliated Hospital of Soochow University Department of Trauma Surgery the 100th Hospital of PLA

AIM:To determine the alterations in rat enterocyte mitochondrial respiratory function and enzyme activities following traumatic brain injury(TBI).METHODS:Fifty-six male SD rats were randomly divided into seven groups(8 rats in each group):a control group(rats with sham operation)and traumatic brain injury groups at 6,12,24 h,days 2,3,and 7after operation.TBI models were induced by Feendy’s free-falling method.Mitochondrial respiratory function(respiratory control ratio and ADP/O ratio)was measured with a Clark oxygen electrode.The activities of respiratory chain complexⅠ-Ⅳand related enzymes were determined by spectrophotometry.RESULTS:Compared with the control group,the mitochondrial respiratory control ratio(RCR)declined at 6 h and remained at a low level until day 7 after TBI(control,5.42±0.46;6 h,5.20±0.18;12 h,4.55±0.35;24 h,3.75±0.22;2 d,4.12±0.53;3 d,3.45±0.41;7 d,5.23±0.24,P<0.01).The value of phosphate-to-oxygen(P/O)significantly decreased at12,24 h,day 2 and day 3,respectively(12 h,3.30±0.10;24 h,2.61±0.21;2 d,2.95±0.18;3 d,2.76±0.09,P<0.01)compared with the control group(3.46±0.12).Two troughs of mitochondrial respiratory function were seen at 24 h and day 3 after TBI.The activities of mitochondrial complex Ⅰ (6 h:110±10,12 h:115±12,24 h:85±9,day 2:80±15,day 3:65±16,P<0.01)and complexⅡ(6 h:105±8,12 h:110±92,24 h:80±10,day 2:76±8,day 3:68±12,P<0.01)were increased at 6 h and 12 h following TBI,and then significantly decreased at 24 h,day 2 and day3,respectively.However,there were no differences in complex Ⅰ andⅡactivities between the control and TBI groups.Furthermore,pyruvate dehydrogenase(PDH)activity was significantly decreased at 6 h and continued up to 7 d after TBI compared with the control group(6 h:90±8,12 h:85±10,24 h:65±12,day 2:60±9,day 3:55±6,day 7:88±11,P<0.01).The changes inα-ketoglutaric dehydrogenase(KGDH)activity were similar to PDH,except that the decrease in KGDH activity began at 12 h after TBI(12 h:90±12,24 h:80±9,day 2:76±15,day 3:68±7,day7:90±13,P<0.01).No significant change in mal

关键词： Mitochondria Brain injury Enterocyte Rats malate d

Molecular Basis of Aluminium Toxicity in Plants: A Review

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American Journal of Plant Sciences 2013年第12期4卷 21-37页

作者： Nidhi Gupta Shailendra Singh Gaurav Ashwani Kumar Department of Biotechnology Chaudhary Charan Singh University Meerut India Department of Botany University of Rajasthan Jaipur India

Aluminium toxicity in acid soils having pH below 5.5, affects the production of staple food crops, vegetables and cash crops worldwide. About 50% of the world’s potentially arable lands are acidic. It is trivalent cationic form i.e. Al3+ that limits the plant’s growth. Absorbed Aluminium inhibits root elongation and adversely affects plant growth. Recently researches have been conducted to understand the mechanism of Aluminium toxicity and resistance which is important for stable food production in future. Aluminium resistance depends on the ability of the plant to tolerate Aluminium in symplast or to exclude it to soil. Physiological and molecular basis of Aluminium toxicity and resistance mechanism are important to understand for developing genetically engineered plants for Al toxicity resistance. This paper provides an overview of the state of art in this field.

关键词： Aluminium Toxicity Acid Soils malate Citrate Wheat Field Crops

Tissue-specific isoenzyme variations in Arabian camel, <i>Camelus dromedaries</i>

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Advances in Bioscience and Biotechnology 2012年第7期3卷 863-868页

作者： Mohammed S. AL-Harbi Sayed A. M. Amer Department of Biology Faculty of Science Taif University Taif Saudi Arabia

malate dehydrogenase, α-esterase and β-esterase isoenzymes have been analyzed by native polyacryla-mide gel electrophoresis in different tissues (liver, kidney, muscle and hump) of the Arabian Camel, Camelus dromedaries in order to study the tissue specificity of these isoenzymes. malate dehy-drogenase recorded three fractions while both este-rases recorded two fractions in different studied tissues. malate dehydrogenase was considered as a key isoenzyme in discriminating among the different studied tissues. The percentage amount of both Mdh-1 and Mdh-2 showed significant difference among the different tissues while Mdh-3 recorded significant variation between muscle and hump tissues. The significant variation in the amount of Mdh isoenzyme (on the level of either total or fractions) among the different studied tissues may reflect the role of this enzyme for energy production in this desert animal. With respect to esterases, the percentage amount for both fractions and the total enzyme did not show significant difference among different tissues except β-Est-2 which was significantly higher in hump than in muscle. This enzyme showed higher thickness and intensity in both liver and kidney than in the muscle and hump indicating its greater activity in both liver and kidney.

关键词： Electrophoresis Esterase malate Dehydrogenase Tissue Specificity Arabian Camel