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Comprehensive analysis of pepc gene family in Populus trichocarpa: Characterization, evolutionary insights, and the role of Ptpepc4-PtLTPG14 interaction in carbon metabolism

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PLANT PHYSIOLOGY AND BIOCHEMISTRY 2025年 220卷 109573页

作者： Wei, Hui Lu, Zixuan Jiang, Hanchun Xue, Chen Xu, Xi Liu, Guoyuan Lian, Bilin Zhong, Fei Movahedi, Ali Zhang, Jian Nantong Univ Sch Life Sci Key Lab Landscape Plant Genet & Breeding Nantong Peoples R China Nanjing Forestry Univ Coll Biol & Environm Nanjing Peoples R China

The phosphoenolpyruvate carboxylase (pepc) is a crucial enzyme involved in the primary carbon metabolism of plants, catalyzing the conversion of phosphoenolpyruvate (PEP) to oxaloacetate (OAA), a key intermediate in various biosynthetic pathways. In this study, we identified five Populus trichocarpa pepcs, renamed Ptpepc1Ptpepc5, which were classified into two subfamilies, PTPC and BTPC, based on phylogenetic analysis. Our analysis revealed significant segmental duplication events during the expansion of Ptpepcs, providing insights into the evolutionary history of these genes in poplar. The syntenic analysis of pepcs between poplar and other species, such as Arabidopsis and willow, highlighted both the diversification and conservation of these genes across different plant species. Protein interaction networks, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis suggested that Ptpepcs may participate in various metabolic pathways related to carbon flow. Expression analysis under stress conditions, including treatments with abscisic acid (ABA), H2O2, and NaCl, indicated potential roles for Ptpepcs in stress responses. Notably, the interaction between Ptpepc4 and PtLTPG14 appeared to play a crucial role in carbon metabolism, laying the groundwork for comprehending the regulatory mechanisms that govern the distribution of carbon among carbohydrates, proteins, and lipids. This insight may have significant implications for the fields of plant breeding and biotechnology.

关键词： pepc Poplar Ptpepc4-PtLTPG14 Carbon metabolism

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Restriction accessibility in isolated nuclei reveals light-induced chromatin reorganization at the pepc promoter in maize

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PLANT MOLECULAR BIOLOGY 2003年第3期52卷 669-678页

作者： Kalamajka, R Hahnen, S Cavalar, M Töpsch, S Weier, D Peterhänsel, C Univ Aachen Inst Biol 1 D-52056 Aachen Germany

Expression of genes necessary to perform C-4 photosynthesis in maize is activated by light. It is not known how this activation is regulated on the chromatin level in vivo. We analysed alterations in the chromatin structure of the promoter of the C-4-specific isoform of phosphoenolpyruvate carboxylase (pepc) after illumination of seedlings. A protocol was established that facilitates the preparation of nuclei from maize leaves with intact chromatin structure and resistance to DNA degradation during prolonged incubation at high temperatures. The presence of non-spliced transcripts from the C-4-pepc gene in the nuclei was demonstrated by RT-PCR. The chromatin was partially digested with restriction endonucleases. Quantitative PCR analyses revealed a clear increase in the accessibility of the promoter chromatin to restriction dependent on illumination of the seedlings. The data indicate chromatin reorganization at the C-4-pepc promoter during activation.

关键词： C-4 photosynthesis chromatin nuclei pepc promoter real-time PCR

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Overexpression of C4pepc caused O₂-insensitive photosynthesis in transgenic rice plants

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PLANT SCIENCE 2002年第2期162卷 257-265页

作者： Agarie, S Miura, A Sumikura, R Tsukamoto, S Nose, A Arima, S Matsuoka, M Miyao-Tokutomi, M Saga Univ Fac Agr Saga 8408502 Japan Nagoya Univ Nagoya Aichi 4648601 Japan Natl Inst Agrobiol Resources Tsukuba Ibaraki 3058602 Japan

We have introduced an intact maize gene for phosphoenolpyruvate carboxylase (pepc) into C3 plants, rice (Oryza saliva cv. Kitaake). Most transgenic rice plants showed high-level expression of the maize gene. pepc was two to three times more active in the leaves of some transgenic plants than in maize leaves. In transformants, the sensitivity of photosynthesis to O-2 inhibition was reduced with the increased activity of the maize C4 pepc. However, the alleviation of O-2 inhibition was not due to an increase in the partial direct fixation of atmospheric CO2 via the enhanced maize pepc, but rather due to the reduced stimulation of photosynthesis with a subatmospheric O-2 level. Pi feeding to the leaves restored CO2 assimilation rate under the subatmospheric O-2 condition, and consequently, the O-2 inhibition in the transformants increased to a level comparable to that of the non-transformants. These results suggested that the O-2-insensitive photosynthesis in the pepc transformants was caused by a Pi limitation of photosynthesis. The activities of two key enzymes for sucrose synthesis, SPS and FBPase, and the sucrose and starch content were reduced in the leaves of the transformants. On the other hand, the dark respiration rate and the malate content in the leaves increased in the transformants. These results indicated that enhanced pepc activity led to a decrease in the availability of Pi in chloroplast via a reduction of the activities of the key enzymes responsible for Pi recycling and it also caused an increased consumption of the substrate (triose-phosphate) in respiration, but not in sucrose biosynthesis. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

关键词： C3 C4 O-2 insensitivity pepc Pi limitation transgenic rice

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Physiological characteristics of the primitive CO_(2) concentrating mechanism in pepc transgenic rice

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Science China(Life Sciences) 2003年第4期46卷 438-446页

作者：焦德茂匡廷云李霞戈巧英黄雪清郝乃斌白克智 Institute of Agrobiological Geneticsand Physiology Jiangsu Academyof Agriculturalsciences Institute of Botany Chinese Academy of Sciences

The relationship between carbon assimilation and high-level expression of the maize pepc in pepc transgenic rice was studied by comparison to that in the untransformed rice, japonica kitaake. Stomatal conductance and photosynthetic rates in pepc transgenic rice were higher than those of untransformed rice, but the increase of stomatal conductance had no statistical correlation with that of photosynthetic rate. Under high levels of light intensity, the protein contents of pepc and CA were increased significantly. Therefore the photosynthetic capacity was increased greatly (50%) with atmospheric CO2 supply. While CO2 release in leaf was reduced and the compensation point was lowered correspondingly under CO2 free conditions. Treatment of the rice with the pepc-specific inhibitor DCDP showed that overexpression of pepc and enhancement of carbon assimilation were related to the stability of Fv/Fm. Labeling with 14CO2 for 20 s showed more 14C was distributed to C4 primary photosynthate asperate in pepc transgenic rice, suggesting that there exists a limiting C4 photosynthetic mechanism in leaves. These results suggest that the primitive CO2 concentrating mechanism found in rice could be reproduced through metabolic engineering, and shed light on the physiological basis for transgenic breeding with high photosynthetic efficiency.

关键词： pepc transgenic rice, phosphoenopyruvate carboxylase (pepc), carbonic anhydrase (CA), stomatal conductance, CO2 concentrating mechanism.

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Light-regulated and cell-specific methylation of the maize pepc promoter

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JOURNAL OF EXPERIMENTAL BOTANY 2012年第3期63卷 1381-1390页

作者： Tolley, Ben J. Woodfield, Helen Wanchana, Samart Bruskiewich, Richard Hibberd, Julian M. Univ Cambridge Dept Plant Sci Cambridge CB2 3EA England Int Rice Res Inst IRRI Manila Philippines

The molecular mechanisms governing pepc expression in maize remain to be fully defined. Differential methylation of a region in the pepc promoter has been shown to correlate with transcript accumulation, however, to date, investigations into the role of DNA methylation in maize pepc expression have relied on the use of methylation-sensitive restriction enzymes. Bisulphite sequencing was used here to provide a single-base resolution methylation map of the maize pepc promoter. It is shown that four cytosine residues in the pepc promoter are heavily methylated in maize root tissue. In leaves, de-methylation of these cytosines is dependent on illumination and is coincident with elevated pepc expression. Furthermore, light-regulated de-methylation of these cytosines occurs only in mesophyll cells. No methylation was discovered in the 0.6 kb promoter required for mesophyll-specific expression indicating that cytosine methylation is not required to direct the cell-specificity of pepc expression. This raises interesting questions regarding the function of the cell-specific cytosine de-methylation observed in the upstream region of the pepc promoter.

关键词： Bundle sheath C-4 photosynthesis maize mesophyll methylation pepc

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Preliminary Study on the Physiological Characteristics of Transgenic Wheat with Maize C₄-pepc Gene in Field Conditions

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CEREAL RESEARCH COMMUNICATIONS 2014年第1期42卷 70-80页

作者： Han, L. L. Xu, W. G. Hu, L. Li, Y. Qi, X. L. Zhang, J. H. Zhang, H. F. Wang, Y. X. Henan Agr Univ Agron Coll Zhengzhou 450002 Peoples R China Henan Acad Agr Sci Wheat Inst Zhengzhou 450002 Peoples R China

To explore the physiological characteristics of the pepc gene in transgenic wheat (Triticum aestivum) plants, pepc activities in various organs of T3 plants were analyzed at Feekes 6.0, Feekes 10.3 and Feekes 11.1, and compared to control, untransformed wheat cultivar Zhoumai 19. Net photosynthetic rates (P-n) in leaves were also measured at the same stages. At Feekes 11.1, both transgenic and control plants were treated with DCDP. Yield traits were surveyed after harvest. The results indicated that P-n and pepc activity in the flag leaf of transgenic wheat were significantly higher than those of the control at different stages. At Feekes 10.3, P-n reached the highest value at 28.2 mu mol m(-2) s(-1) and pepc activity reached the highest value at 104.6 mu mol h(-1) mg(-1). Both factors significantly increased by 21% compared to the control at Feekes 11.1. pepc activity in the flag leaf of transgenic plants was significantly higher than that of non-leaf organs. P-n of transgenic plants was greatly reduced after DCDP treatment. In the flag leaf of transgenic wheat, P-n was significantly correlated to pepc activities at 0.01 probability level with a correlation coefficient of 0.8957**. The yield traits of transgenic line 1-27-3, such as 1000-grain weight, single spike weight and harvest index were higher than those of the control. Additionally, the spike weight of 1-27-3 showed an increase of approximately 9.5% compared to the control. These results indicated that the expression of maize (Zea mays) pepc gene was different across various organs of transgenic wheat and across every growth stage. Therefore, we conclude that introducing maize pepc gene into wheat plants can increase their P-n and improve production.

关键词： wheat transgenic pepc net photosynthetic rate

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Contribution of carbon fixed by Rubisco and pepc to phloem export in the Crassulacean acid metabolism plant Kalanchoe daigremontiana

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JOURNAL OF EXPERIMENTAL BOTANY 2010年第5期61卷 1375-1383页

作者： Wild, Birgit Wanek, Wolfgang Postl, Wolfgang Richter, Andreas Univ Vienna Dept Chem Ecol & Ecosyst Res A-1090 Vienna Austria Univ Vienna Dept Mol Syst Biol A-1090 Vienna Austria

Crassulacean acid metabolism (CAM) plants exhibit a complex interplay between CO(2) fixation by phosphoenolpyruvate carboxylase (pepc) and ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco), and carbon demand for CAM maintenance and growth. This study investigated the flux of carbon from pepc and direct Rubisco fixation to different leaf carbon pools and to phloem sap over the diurnal cycle. Concentrations and carbon isotope compositions of starch, soluble sugars, and organic acids were determined in leaves and phloem exudates of Kalanchoe daigremontiana Hamet et Perr., and related to CO(2) fixation by pepc and Rubisco. Three types of leaf carbon pools could be distinguished. (i) Starch and malate pools were dominant and showed a pattern of reciprocal mobilization and accumulation (85/54 and 13/48 mg C g(-1) DW, respective, at the beginning/end of phase I). The carbon isotope composition of these pools was compatible with predominant pepc fixation (delta(13)C values of -13 and -11 parts per thousand for starch and malate compared to -11 parts per thousand of pepc fixed carbon). (ii) Isotopic composition (-17 parts per thousand and -14 parts per thousand) and concentration of glucose and fructose (2 and 3 mg C g(-1) DW, respectively) were not affected by diurnal metabolism, suggesting a low turnover. (iii) Sucrose (1-3 mg C g(-1) DW), in contrast, exhibited large diurnal changes in delta(13)C values (from -17 parts per thousand in the evening to -12 parts per thousand in the morning), which were not matched by net changes in sucrose concentration. This suggests a high sucrose turnover, fed by nocturnal starch degradation and direct Rubisco fixation during the day. A detailed dissection of the carbon fixation and mobilization pattern in K. daigremontiana revealed that direct fixation of Rubisco during the light accounted for 30% of phloem sucrose, but only 15% of fixed carbon, indicating that carbon from direct Rubisco fixation was preferentially used for leaf

关键词： Compound-specific isotope analysis malate pepc Rubisco starch sucrose

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Characteristics of Chlorophyll Fluorescence and Antioxidant-Oxidant Balance in pepc and PPDK Transgenic Rice under Aluminum Stress

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RUSSIAN JOURNAL OF PLANT PHYSIOLOGY 2018年第1期65卷 49-56页

作者： Zhang, Y. H. Wang, E. M. Zhao, T. F. Wang, Q. Q. Chen, L. J. Anhui Agr Univ Sch Resources & Environm Anhui Prov Key Lab Farmland Ecol Conservat & Poll Hefei 230036 Anhui Peoples R China Anhui Agr Univ Coll Anim Sci & Technol Hefei 230036 Anhui Peoples R China

Aluminum is one of the most important heavy metals inducing stress during plant growth and development. In this study, transgenic rice (Oryza sativa L., cv. Kitaake) plants expressing the maize C-4 pepc and PPDK genes were evaluated for aluminum tolerance. A 4.3 and 19.1 folds increase of PPDK and pepc activities in transgenic rice produced increases in root exudation of oxalate, malate, and citrate (1.20, 1.41, and 1.65 times, respectively) compared to untransformed (WT) plants. Transgenic rice had enhanced aluminum tolerance compared to WT based on chlorophyll fluorescence and chlorophyll levels. Transgenic plants under aluminum stress also had decreased lipid membrane oxidative damage and higher levels of ROS-scavenging enzyme activity. The pepc and PPDK genes play an important role in aluminum stress tolerance by increasing the effluxes of organic acids.

关键词： Oryza sativa transgenic rice pepc PPDK organic acids efflux chlorophyll fluorescence antioxidant system aluminum stress

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Catalytic properties of the cysteine aminopeptidase pepc, a bacterial bleomycin hydrolase

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BIOCHIMICA ET BIOPHYSICA ACTA-PROTEIN STRUCTURE AND MOLECULAR ENZYMOLOGY 1998年第1期1383卷 63-70页

作者： Mistou, MY Gripon, JC INRA Unite Biochim & Struct Prot F-78352 Jouy En Josas France

pepc is a cytoplasmic thiol aminopeptidase widely conserved among lactic acid bacteria. pepc: from Lactococcus lactis shares 35-38% identity with aminopeptidases of eukaryotic origins: the yeast and mammalian bleomycin hydrolases (BLMase). In this work we investigated the hydrolytic activity of pepc towards various substrates: bleomycin A2, aminoacyl-p-nitroanilides (pNA) and peptides. First, we found the bleomycin hydrolase activity of lactococcal pepc and measured similar kinetics parameters to those reported for the mammalian BLMase. Second, the result obtained on aminoacyl-pNA confirmed the capacity of the enzyme to release a broad range of amino acids and the pH activity profile suggests the presence of an ionic interaction between the enzyme and the flee a-amino group of the substrate. Third, the aminopeptidase activity measured on peptide substrates revealed that pepc possesses an extended binding site which interacts with the peptidic backbone of the substrate. The hydrolytic efficiency is highly dependent on the length of the peptide, optimal for tetrapeptides and further enhanced by the presence of hydrophobic residues in the P' positions of the substrate. These enzymatic properties are of importance for the design of specific inhibitors and the biological function of the bleomycin hydrolases. (C) 1998 Elsevier Science B.V.

关键词： pepc cysteine aminopeptidase bleomycin hydrolase subsite specificity

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Origins and chromosome differentiation of Thinopyrum elongatum revealed by pepc and Pgk1 genes and ND-FISH

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GENOME 2021年第10期64卷 901-913页

作者： Dai, Yi Huang, Shuai Sun, Genlou Li, Haifeng Chen, Shiqiang Gao, Yong Chen, Jianmin Yangzhou Univ Inst Agr Sci Joint Int Res Lab Agr & Agriprod Safety Minist Educ China Yangzhou 225009 Jiangsu Peoples R China Yangzhou Univ Inst Technol Dev Joint Int Res Lab Agr & Agriprod Safety Minist Educ China Yangzhou 225009 Jiangsu Peoples R China Yangzhou Univ Coinnovat Ctr Modern Prod Technol Grain Crops Jia Jiangsu Key Labs Crop Genet & Physiol & Plant Fun Minist Educ Yangzhou 225009 Jiangsu Peoples R China St Marys Univ Dept Biol Halifax NS B3H 3C3 Canada Yangzhou Polytech Coll Yangzhou 225009 Jiangsu Peoples R China Inst Agr Sci Yangzhou 225009 Jiangsu Peoples R China

Thinopyrum elongatum is an important gene pool for wheat genetic improvement. However, the origins of the Thinopyrum genomes and the nature of the genus' intraspecific relationships are still controversial. In this study, we used single-copy nuclear genes and non-denaturing fluorescence in situ hybridization (NDFISH) to characterize genome constitution and chromosome differentiation in Th. elongatum. According to phylogenetic analyses based on pepc and Pgk1 genes, there was an E genome with three versions (Ee, Eb, Ex) and St genomes in the polyploid Th. elongatum. The ND-FISH results of pSc119.2 and pAs1 revealed that the karyotypes of diploid Th. elongatum and Th. bessarabicum were different, and the chromosome differentiation occurred among accessions of the diploid Th. elongatum. In addition, the tetraploid Th. elongatum has two groups of NDFISH karyotype, indicating that the tetraploid Th. elongatum might be a segmental allotetraploid. In summary, our results suggested that the diploid Th. elongatum, Th. Bessarabicum, and Pseudoroegneria were the donors of the Ee, Eb, and St genomes to the polyploid Th. elongatum, respectively.

关键词： Thinopyrum elongatum phylogeny pepc Pgk1 ND-FISH

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