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Shi M, Zhao L, Wang Y. Identification and Characterization of Genes Encoding the Hydroxypyruvate Reductases in Chlamydomonas Reveal Their Distinct Roles in Photorespiration. Front Plant Sci 2021; 12:690296. [PMID: 34249060 PMCID: PMC8264790 DOI: 10.3389/fpls.2021.690296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 05/31/2021] [Indexed: 06/13/2023]
Abstract
Photorespiration plays an important role in maintaining normal physiological metabolism in higher plants and other oxygenic organisms, such as algae. The unicellular eukaryotic organism Chlamydomonas is reported to have a photorespiration system different from that in higher plants, and only two out of nine genes encoding photorespiratory enzymes have been experimentally characterized. Hydroxypyruvate reductase (HPR), which is responsible for the conversion of hydroxypyruvate into glycerate, is poorly understood and not yet explored in Chlamydomonas. To identify the candidate genes encoding hydroxypyruvate reductases in Chlamydomonas (CrHPR) and uncover their elusive functions, we performed sequence comparison, enzyme activity measurement, subcellular localization, and analysis of knockout/knockdown strains. Together, we identify five proteins to be good candidates for CrHPRs, all of which are detected with the activity of hydroxypyruvate reductase. CrHPR1, a nicotinamide adenine dinucleotide (NADH)-dependent enzyme in mitochondria, may function as the major component of photorespiration. Its deletion causes severe photorespiratory defects. CrHPR2 takes part in the cytosolic bypass of photorespiration as the compensatory pathway of CrHPR1 for the reduction of hydroxypyruvate. CrHPR4, with NADH as the cofactor, may participate in photorespiration by acting as the chloroplastidial glyoxylate reductase in glycolate-quinone oxidoreductase system. Therefore, the results reveal that CrHPRs are far more complex than previously recognized and provide a greatly expanded knowledge base for studies to understand how CrHPRs perform their functions in photorespiration. These will facilitate both modification of photorespiration and genetic engineering for crop improvement by synthetic biology.
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Affiliation(s)
- Menglin Shi
- College of Life Sciences, Nankai University, Tianjin, China
| | - Lei Zhao
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
- National Center of Technology Innovation for Synthetic Biology, Tianjin, China
| | - Yong Wang
- College of Life Sciences, Nankai University, Tianjin, China
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Timm S, Nunes-Nesi A, Florian A, Eisenhut M, Morgenthal K, Wirtz M, Hell R, Weckwerth W, Hagemann M, Fernie AR, Bauwe H. Metabolite Profiling in Arabidopsisthaliana with Moderately Impaired Photorespiration Reveals Novel Metabolic Links and Compensatory Mechanisms of Photorespiration. Metabolites 2021; 11:391. [PMID: 34203750 DOI: 10.3390/metabo11060391] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/09/2021] [Accepted: 06/11/2021] [Indexed: 01/19/2023] Open
Abstract
Photorespiration is an integral component of plant primary metabolism. Accordingly, it has been often observed that impairing the photorespiratory flux negatively impacts other cellular processes. In this study, the metabolic acclimation of the Arabidopsisthaliana wild type was compared with the hydroxypyruvate reductase 1 (HPR1; hpr1) mutant, displaying only a moderately reduced photorespiratory flux. Plants were analyzed during development and under varying photoperiods with a combination of non-targeted and targeted metabolome analysis, as well as 13C- and 14C-labeling approaches. The results showed that HPR1 deficiency is more critical for photorespiration during the vegetative compared to the regenerative growth phase. A shorter photoperiod seems to slowdown the photorespiratory metabolite conversion mostly at the glycerate kinase and glycine decarboxylase steps compared to long days. It is demonstrated that even a moderate impairment of photorespiration severely reduces the leaf-carbohydrate status and impacts on sulfur metabolism. Isotope labeling approaches revealed an increased CO2 release from hpr1 leaves, most likely occurring from enhanced non-enzymatic 3-hydroxypyruvate decarboxylation and a higher flux from serine towards ethanolamine through serine decarboxylase. Collectively, the study provides evidence that the moderate hpr1 mutant is an excellent tool to unravel the underlying mechanisms governing the regulation of metabolic linkages of photorespiration with plant primary metabolism.
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Kotb MA, Hamza AF, Abd El Kader H, El Monayeri M, Mosallam DS, Ali N, Basanti CWS, Bazaraa H, Abdelrahman H, Nabhan MM, Abd El Baky H, El Sorogy STM, Kamel IEM, Ismail H, Ramadan Y, Abd El Rahman SM, Soliman NA. Combined liver-kidney transplantation for primary hyperoxaluria type I in children: Single Center Experience. Pediatr Transplant 2019; 23:e13313. [PMID: 30475440 DOI: 10.1111/petr.13313] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 08/31/2018] [Accepted: 10/02/2018] [Indexed: 12/11/2022]
Abstract
Primary hyperoxalurias are rare inborn errors of metabolism with deficiency of hepatic enzymes that lead to excessive urinary oxalate excretion and overproduction of oxalate which is deposited in various organs. Hyperoxaluria results in serious morbid-ity, end stage kidney disease (ESKD), and mortality if left untreated. Combined liver kidney transplantation (CLKT) is recognized as a management of ESKD for children with hyperoxaluria type 1 (PH1). This study aimed to report outcome of CLKT in a pediatric cohort of PH1 patients, through retrospective analysis of data of 8 children (2 girls and 6 boys) who presented by PH1 to Wadi El Nil Pediatric Living Related Liver Transplant Unit during 2001-2017. Mean age at transplant was 8.2 ± 4 years. Only three of the children underwent confirmatory genotyping. Three patients died prior to surgery on waiting list. The first attempt at CLKT was consecutive, and despite initial successful liver transplant, the girl died of biliary peritonitis prior to scheduled renal transplant. Of the four who underwent simultaneous CLKT, only two survived and are well, one with insignificant complications, and other suffered from abdominal Burkitt lymphoma managed by excision and resection anastomosis, four cycles of rituximab, cyclophosphamide, vincristine, and prednisone. The other two died, one due to uncontrollable bleeding within 36 hours of procedure, while the other died awaiting renal transplant after loss of renal graft to recurrent renal oxalosis 6 months post-transplant. PH1 with ESKD is a rare disease; simultaneous CLKT offers good quality of life for afflicted children. Graft shortage and renal graft loss to oxalosis challenge the outcome.
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Affiliation(s)
- Magd A Kotb
- Pediatric Hepatology Unit, Faculty of Medicine, Department of Pediatrics, Cairo University, Cairo, Egypt.,Wadi El Nil Hospital, Pediatric Living-Related Liver Transplantation Team, Cairo, Egypt
| | - Alaa F Hamza
- Wadi El Nil Hospital, Pediatric Living-Related Liver Transplantation Team, Cairo, Egypt.,Faculty of Medicine, Department of Pediatric Surgery, Ain Shams University, Cairo, Egypt
| | - Hesham Abd El Kader
- Wadi El Nil Hospital, Pediatric Living-Related Liver Transplantation Team, Cairo, Egypt.,Faculty of Medicine, Department of Pediatric Surgery, Ain Shams University, Cairo, Egypt
| | - Magda El Monayeri
- Wadi El Nil Hospital, Pediatric Living-Related Liver Transplantation Team, Cairo, Egypt.,Faculty of Medicine, Department of Pathology, Ain Shams University, Cairo, Egypt
| | - Dalia S Mosallam
- Pediatric Hepatology Unit, Faculty of Medicine, Department of Pediatrics, Cairo University, Cairo, Egypt
| | - Nazira Ali
- Pediatric Hepatology Unit, Faculty of Medicine, Department of Pediatrics, Cairo University, Cairo, Egypt.,Wadi El Nil Hospital, Pediatric Living-Related Liver Transplantation Team, Cairo, Egypt
| | | | - Hafez Bazaraa
- Pediatric Hepatology Unit, Faculty of Medicine, Department of Pediatrics, Cairo University, Cairo, Egypt.,Department of Pediatrics, Center of Pediatric Nephrology & Transplantation, Kasr Al Ainy School of Medicine, Cairo University, Cairo, Egypt.,Egyptian Group for Orphan Renal Diseases (EGORD), Cairo, Egypt
| | - Hany Abdelrahman
- Pediatric Oncology, National Cancer Institute, Cairo University, Cairo, Egypt
| | - Marwa M Nabhan
- Pediatric Hepatology Unit, Faculty of Medicine, Department of Pediatrics, Cairo University, Cairo, Egypt.,Department of Pediatrics, Center of Pediatric Nephrology & Transplantation, Kasr Al Ainy School of Medicine, Cairo University, Cairo, Egypt.,Egyptian Group for Orphan Renal Diseases (EGORD), Cairo, Egypt
| | - Hend Abd El Baky
- Pediatric Hepatology Unit, Faculty of Medicine, Department of Pediatrics, Cairo University, Cairo, Egypt.,Wadi El Nil Hospital, Pediatric Living-Related Liver Transplantation Team, Cairo, Egypt
| | | | - Inas E M Kamel
- Department of Pediatrics, National Research Center, Cairo, Egypt
| | - Hoda Ismail
- Wadi El Nil Hospital, Pediatric Living-Related Liver Transplantation Team, Cairo, Egypt.,Department of Pediatrics, Wadi El Nil Hospital, Cairo, Egypt
| | - Yasmin Ramadan
- Pediatric Hepatology Unit, Faculty of Medicine, Department of Pediatrics, Cairo University, Cairo, Egypt.,Department of Pediatrics, Center of Pediatric Nephrology & Transplantation, Kasr Al Ainy School of Medicine, Cairo University, Cairo, Egypt.,Egyptian Group for Orphan Renal Diseases (EGORD), Cairo, Egypt
| | - Safaa M Abd El Rahman
- Pediatric Hepatology Unit, Faculty of Medicine, Department of Pediatrics, Cairo University, Cairo, Egypt.,Department of Pediatrics, Center of Pediatric Nephrology & Transplantation, Kasr Al Ainy School of Medicine, Cairo University, Cairo, Egypt.,Pediatric Oncology, National Cancer Institute, Cairo University, Cairo, Egypt
| | - Neveen A Soliman
- Pediatric Hepatology Unit, Faculty of Medicine, Department of Pediatrics, Cairo University, Cairo, Egypt.,Department of Pediatrics, Center of Pediatric Nephrology & Transplantation, Kasr Al Ainy School of Medicine, Cairo University, Cairo, Egypt.,Egyptian Group for Orphan Renal Diseases (EGORD), Cairo, Egypt
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Ye N, Yang G, Chen Y, Zhang C, Zhang J, Peng X. Two hydroxypyruvate reductases encoded by OsHPR1 and OsHPR2 are involved in photorespiratory metabolism in rice. J Integr Plant Biol 2014; 56:170-180. [PMID: 24401104 DOI: 10.1111/jipb.12125] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Accepted: 10/28/2013] [Indexed: 06/03/2023]
Abstract
Mutations in the photorespiration pathway display a lethal phenotype in atmospheric air, which can be fully recovered by elevated CO2 . An exception is that mutants of peroxisomal hydroxypyruvate reductase (HPR1) do not have this phenotype, indicating the presence of cytosolic bypass in the photorespiration pathway. In this study, we constructed overexpression of the OsHPR1 gene and RNA interference plants of OsHPR1 and OsHPR2 genes in rice (Oryza sativa L. cv. Zhonghua 11). Results from reverse transcription-polymerase chain reaction (RT-PCR), Western blot, and enzyme assays showed that HPR1 activity changed significantly in corresponding transgenic lines without any effect on HPR2 activity, which is the same for HPR2. However, metabolite analysis and the serine glyoxylate aminotransferase (SGAT) activity assay showed that the metabolite flux of photorespiration was disturbed in RNAi lines of both HPR genes. Furthermore, HPR1 and HPR2 proteins were located to the peroxisome and cytosol, respectively, by transient expression experiment. Double mutant hpr1 × hpr2 was generated by crossing individual mutant of hpr1 and hpr2. The phenotypes of all transgenic lines were determined in ambient air and CO2 -elevated air. The phenotype typical of photorespiration mutants was observed only where activity of both HPR1 and HPR2 were downregulated in the same line. These findings demonstrate that two hydroxypyruvate reductases encoded by OsHPR1 and OsHPR2 are involved in photorespiratory metabolism in rice.
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Affiliation(s)
- Nenghui Ye
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, China; Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
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Hoover GJ, Jørgensen R, Rochon A, Bajwa VS, Merrill AR, Shelp BJ. Identification of catalytically important amino acid residues for enzymatic reduction of glyoxylate in plants. Biochim Biophys Acta 2013; 1834:2663-71. [PMID: 24076009 DOI: 10.1016/j.bbapap.2013.09.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Revised: 09/15/2013] [Accepted: 09/18/2013] [Indexed: 02/06/2023]
Abstract
NADPH-dependent glyoxylate reductases from Arabidopsis thaliana (AtGLYR) convert both glyoxylate and succinic semialdehyde into their corresponding hydroxyacid equivalents. The primary sequence of cytosolic AtGLYR1 reveals several sequence elements that are consistent with the β-HAD (β-hydroxyacid dehydrogenase) protein family, whose members include 3-hydroxyisobutyrate dehydrogenase, tartronate semialdehyde reductase and 6-phosphogluconate dehydrogenase. Here, site-directed mutagenesis was utilized to identify catalytically important amino acid residues for glyoxylate reduction in AtGLYR1. Kinetic studies and binding assays established that Lys170 is essential for catalysis, Phe231, Asp239, Ser121 and Thr95 are more important in substrate binding than in catalysis, and Asn174 is more important in catalysis. The low activity of the mutant enzymes precluded kinetic studies with succinic semialdehyde. The crystal structure of AtGLYR1 in the absence of substrate was solved to 2.1Å by molecular replacement using a previously unrecognized member of the β-HAD family, cytokine-like nuclear factor, thereby enabling the 3-D structure of the protein to be modeled with substrate and co-factor. Structural alignment of AtGLYR1 with β-HAD family members provided support for the essentiality of Lys170, Phe173, Asp239, Ser121, Asn174 and Thr95 in the active site and preliminary support for an acid/base catalytic mechanism involving Lys170 as the general acid and a conserved active-site water molecule. This information established that AtGLYR1 is a member of the β-HAD protein family. Sequence and activity comparisons indicated that AtGLYR1 and the plastidial AtGLYR2 possess structural features that are absent in Arabidopsis hydroxypyruvate reductases and probably account for their stronger preference for glyoxylate over hydroxypyruvate.
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Affiliation(s)
- Gordon J Hoover
- Department of Plant Agriculture, University of Guelph, Guelph, ON N1G 2W1, Canada
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