1
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Microbial arginine deiminase: A multifaceted green catalyst in biomedical sciences. Int J Biol Macromol 2022; 196:151-162. [PMID: 34920062 DOI: 10.1016/j.ijbiomac.2021.12.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 11/03/2021] [Accepted: 12/04/2021] [Indexed: 12/18/2022]
Abstract
Arginine deiminase is a well-recognized guanidino-modifying hydrolase that catalyzes the conversion of L-arginine to citrulline and ammonia. Their biopotential to regress tumors via amino acid deprivation therapy (AADT) has been well established. PEGylated formulation of recombinant Mycoplasma ADI is in the last-phase clinical trials against various arginine-auxotrophic cancers like hepatocellular carcinoma, melanoma, and mesothelioma. Recently, ADIs have attained immense importance in several other biomedical applications, namely treatment of Alzheimer's, as an antiviral drug, bioproduction of nutraceutical L-citrulline and bio-analytics involving L-arginine detection. Considering the wide applications of this biodrug, the demand for ADI is expected to escalate several-fold in the coming years. However, the sustainable production aspects of the enzyme with improved pharmacokinetics is still limited, creating bottlenecks for effective biopharmaceutical development. To circumvent the lacunae in enzyme production with appropriate paradigms of 'quality-by-design' an explicit overview of its properties with 'biobetter' formulations strategies are required. Present review provides an insight into all the potential biomedical applications of ADI along with the improvements required for its reach to clinics. Recent research advances with special emphasis on the development of ADI as a 'biobetter' enzyme have also been comprehensively elaborated.
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2
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Lin J, Luo X, Gänzle MG, Luo L. Characterization of the two nonidentical ArgR regulators of Tetragenococcus halophilus and their regulatory effects on arginine metabolism. Appl Microbiol Biotechnol 2020; 104:8775-8787. [PMID: 32880693 DOI: 10.1007/s00253-020-10868-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 08/06/2020] [Accepted: 08/26/2020] [Indexed: 11/25/2022]
Abstract
The halophilic lactic acid bacterium Tetragenococcus halophilus has been widely used in high-salinity fermentation processes of food. Previous studies have indicated that the catabolism of arginine may contribute to the osmotic stress adaptation of T. halophilus. Unusually, in the chromosome of T. halophilus, preceding the arginine deiminase (ADI) operon, locate two co-transcribed genes, both encoding an ArgR regulator; similar structure was rarely found and the roles of the regulators have not been demonstrated. In the current study, regulatory roles of these two nonidentical ArgR regulators on the arginine metabolism of T. halophilus were investigated. The results show that these two regulators play different roles in arginine metabolism, ArgR1 acts as a negative regulator of the ADI pathway by binding to the promoter sequences and repressing the transcription of genes, and the addition of arginine or hyper-osmotic stress conditions can abolish the ArgR1 repression, whereas ArgR2 negatively regulates the genes involved in arginine biosynthesis. Our study found that despite the commonly known roles of the ArgR regulators as the activator of arginine catabolism and the repressor of arginine biosynthesis, which are found in most studied bacteria possessed one ArgR regulator, the two nonidentical ArgR regulators of T. halophilus both act as repressors, and the repression by which is regulated when sensing changes of environments. By revealing the regulation of arginine metabolism, the current study provides molecular insights and potential tools for future applications of halophiles in biotechnology. KEY POINTS: • The expression of the ADI pathway of T. halophilus is regulated by carbon sources and osmotic stress. • The arginine metabolism process of T. halophilus is fine-tuned by the two ArgR regulators. • The ADI pathway may contribute to the osmotic stress adaptation by generating more energy and accumulating citrulline which acts as compatible solute.
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Affiliation(s)
- Jieting Lin
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, People's Republic of China
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, South China University of Technology, Guangzhou, 510006, People's Republic of China
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Agriculture/Forestry Centre, Edmonton, Alberta, T6G 2P5, Canada
| | - Xiaotong Luo
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, People's Republic of China
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, South China University of Technology, Guangzhou, 510006, People's Republic of China
| | - Michael G Gänzle
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Agriculture/Forestry Centre, Edmonton, Alberta, T6G 2P5, Canada
| | - Lixin Luo
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, People's Republic of China.
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, South China University of Technology, Guangzhou, 510006, People's Republic of China.
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3
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Lauwaet T, Miyamoto Y, Ihara S, Le C, Kalisiak J, Korthals KA, Ghassemian M, Smith DK, Sharpless KB, Fokin VV, Eckmann L. Click chemistry-facilitated comprehensive identification of proteins adducted by antimicrobial 5-nitroimidazoles for discovery of alternative drug targets against giardiasis. PLoS Negl Trop Dis 2020; 14:e0008224. [PMID: 32302296 PMCID: PMC7190177 DOI: 10.1371/journal.pntd.0008224] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 04/29/2020] [Accepted: 03/16/2020] [Indexed: 12/21/2022] Open
Abstract
Giardiasis and other protozoan infections are major worldwide causes of morbidity and mortality, yet development of new antimicrobial agents with improved efficacy and ability to override increasingly common drug resistance remains a major challenge. Antimicrobial drug development typically proceeds by broad functional screens of large chemical libraries or hypothesis-driven exploration of single microbial targets, but both strategies have challenges that have limited the introduction of new antimicrobials. Here, we describe an alternative drug development strategy that identifies a sufficient but manageable number of promising targets, while reducing the risk of pursuing targets of unproven value. The strategy is based on defining and exploiting the incompletely understood adduction targets of 5-nitroimidazoles, which are proven antimicrobials against a wide range of anaerobic protozoan and bacterial pathogens. Comprehensive adductome analysis by modified click chemistry and multi-dimensional proteomics were applied to the model pathogen Giardia lamblia to identify dozens of adducted protein targets common to both 5'-nitroimidazole-sensitive and -resistant cells. The list was highly enriched for known targets in G. lamblia, including arginine deiminase, α-tubulin, carbamate kinase, and heat shock protein 90, demonstrating the utility of the approach. Importantly, over twenty potential novel drug targets were identified. Inhibitors of two representative new targets, NADP-specific glutamate dehydrogenase and peroxiredoxin, were found to have significant antigiardial activity. Furthermore, all the identified targets remained available in resistant cells, since giardicidal activity of the respective inhibitors was not impacted by resistance to 5'-nitroimidazoles. These results demonstrate that the combined use of click chemistry and proteomics has the potential to reveal alternative drug targets for overcoming antimicrobial drug resistance in protozoan parasites.
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Affiliation(s)
- Tineke Lauwaet
- Department of Pathology, University of California, San Diego, La Jolla, California, United States of America
| | - Yukiko Miyamoto
- Department of Medicine, University of California, San Diego, La Jolla, California, United States of America
| | - Sozaburo Ihara
- Department of Medicine, University of California, San Diego, La Jolla, California, United States of America.,Division of Gastroenterology, The Institute for Adult Diseases, Asahi Life Foundation, Tokyo, Japan
| | - Christine Le
- Department of Medicine, University of California, San Diego, La Jolla, California, United States of America
| | - Jarosław Kalisiak
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Keith A Korthals
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Majid Ghassemian
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, United States of America
| | - Diane K Smith
- Department of Chemistry and Biochemistry, San Diego State University, San Diego, California, United States of America
| | - K Barry Sharpless
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Valery V Fokin
- Department of Chemistry, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California, United States of America
| | - Lars Eckmann
- Department of Medicine, University of California, San Diego, La Jolla, California, United States of America
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4
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Müller J, Vermathen M, Leitsch D, Vermathen P, Müller N. Metabolomic Profiling of Wildtype and Transgenic Giardia lamblia Strains by 1H HR-MAS NMR Spectroscopy. Metabolites 2020; 10:metabo10020053. [PMID: 32019059 PMCID: PMC7073884 DOI: 10.3390/metabo10020053] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/21/2020] [Accepted: 01/28/2020] [Indexed: 12/24/2022] Open
Abstract
Giardia lamblia, a causative agent of persistent diarrhea in humans, domestic animals, and cattle, is usually treated with nitro compounds. Consequently, enzymes involved in anaerobic nitro reduction have been investigated in detail as potential targets. Their role within the normal metabolic context is, however, not understood. Using 1H high-resolution magic angle spinning (HR-MAS) NMR spectroscopy, we analyzed the metabolomes of G. lamblia trophozoites overexpressing three nitroreductases (NR1–NR3) and thioredoxin reductase (TrxR), most likely a scavenger of reactive oxygen species, as suggested by the results published in this study. We compared the patterns to convenient controls and to the situation in the nitro drug resistant strain C4 where NR1 is downregulated. We identified 27 metabolites in G. lamblia trophozoites. Excluding metabolites of high variability among different wildtype populations, only trophozoites overexpressing NR1 presented a distinct pattern of nine metabolites, in particular arginine catabolites, differing from the respective controls. This pattern matched a differential pattern between wildtype and strain C4. This suggests that NR1 interferes with arginine and thus energy metabolism. The exact metabolic function of NR1 (and the other nitroreductases) remains to be elucidated.
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Affiliation(s)
- Joachim Müller
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Länggass-Strasse 122, CH-3012 Bern, Switzerland;
- Correspondence:
| | - Martina Vermathen
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland;
| | - David Leitsch
- Institute of Specific Prophylaxis and Tropical Medicine, Medical University of Vienna, Kinderspitalgasse 15, A-1090 Vienna, Austria;
| | - Peter Vermathen
- Departments of BioMedical Research and Radiology, University and Inselspital Bern, sitem-insel AG Freiburgstr. 3, CH-3010 Bern, Switzerland;
| | - Norbert Müller
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Länggass-Strasse 122, CH-3012 Bern, Switzerland;
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López-Velázquez G, Fernández-Lainez C, de la Mora-de la Mora JI, Caudillo de la Portilla D, Reynoso-Robles R, González-Maciel A, Ridaura C, García-Torres I, Gutiérrez-Castrellón P, Olivos-García A, Flores-López LA, Enríquez-Flores S. On the molecular and cellular effects of omeprazole to further support its effectiveness as an antigiardial drug. Sci Rep 2019; 9:8922. [PMID: 31222100 PMCID: PMC6586891 DOI: 10.1038/s41598-019-45529-w] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 06/05/2019] [Indexed: 01/09/2023] Open
Abstract
Research on Giardia lamblia has accumulated large information about its molecular cell biology and infection biology. However, giardiasis is still one of the commonest parasitic diarrheal diseases affecting humans. Additionally, an alarming increase in cases refractory to conventional treatment has been reported in low prevalence settings. Consequently, efforts directed toward supporting the efficient use of alternative drugs, and the study of their molecular targets appears promising. Repurposing of proton pump inhibitors is effective in vitro against the parasite and the toxic activity is associated with the inhibition of the G. lamblia triosephosphate isomerase (GlTIM) via the formation of covalent adducts with cysteine residue at position 222. Herein, we evaluate the effectiveness of omeprazole in vitro and in situ on GlTIM mutants lacking the most superficial cysteines. We studied the influence on the glycolysis of Giardia trophozoites treated with omeprazole and characterized, for the first time, the morphological effect caused by this drug on the parasite. Our results support the effectiveness of omeprazole against GlTIM despite of the possibility to mutate the druggable amino acid targets as an adaptive response. Also, we further characterized the effect of omeprazole on trophozoites and discuss the possible mechanism involved in its antigiardial effect.
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Affiliation(s)
- Gabriel López-Velázquez
- Grupo de Investigación en Biomoléculas y Salud Infantil, Laboratorio de EIMyT, Instituto Nacional de Pediatría, Ciudad de México, 04530, Mexico.
| | - Cynthia Fernández-Lainez
- Laboratorio de Errores Innatos del Metabolismo y Tamiz, Instituto Nacional de Pediatría, Ciudad de México, 04530, Mexico
| | - José Ignacio de la Mora-de la Mora
- Grupo de Investigación en Biomoléculas y Salud Infantil, Laboratorio de EIMyT, Instituto Nacional de Pediatría, Ciudad de México, 04530, Mexico
| | - Daniela Caudillo de la Portilla
- Grupo de Investigación en Biomoléculas y Salud Infantil, Laboratorio de EIMyT, Instituto Nacional de Pediatría, Ciudad de México, 04530, Mexico
| | - Rafael Reynoso-Robles
- Laboratorio de Morfología Celular y Tisular, Instituto Nacional de Pediatría, Ciudad de México, 04530, Mexico
| | - Angélica González-Maciel
- Laboratorio de Morfología Celular y Tisular, Instituto Nacional de Pediatría, Ciudad de México, 04530, Mexico
| | - Cecilia Ridaura
- Departamento de Patología, Instituto Nacional de Pediatría, Ciudad de México, 04530, Mexico
| | - Itzhel García-Torres
- Grupo de Investigación en Biomoléculas y Salud Infantil, Laboratorio de EIMyT, Instituto Nacional de Pediatría, Ciudad de México, 04530, Mexico
| | | | - Alfonso Olivos-García
- Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México y Hospital General, Ciudad de México, 04510, Mexico
| | - Luis Antonio Flores-López
- Grupo de Investigación en Biomoléculas y Salud Infantil, Laboratorio de EIMyT, Instituto Nacional de Pediatría, Ciudad de México, 04530, Mexico.,CONACYT-Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México, 04530, Mexico
| | - Sergio Enríquez-Flores
- Grupo de Investigación en Biomoléculas y Salud Infantil, Laboratorio de EIMyT, Instituto Nacional de Pediatría, Ciudad de México, 04530, Mexico.
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6
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Patil MD, Rathod VP, Bihade UR, Banerjee UC. Purification and characterization of arginine deiminase from Pseudomonas putida: Structural insights of the differential affinities of l-arginine analogues. J Biosci Bioeng 2019; 127:129-137. [DOI: 10.1016/j.jbiosc.2018.07.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 06/20/2018] [Accepted: 07/23/2018] [Indexed: 10/28/2022]
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7
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Zarei M, Rahbar MR, Morowvat MH, Nezafat N, Negahdaripour M, Berenjian A, Ghasemi Y. Arginine Deiminase: Current Understanding and Applications. Recent Pat Biotechnol 2019; 13:124-136. [PMID: 30569861 DOI: 10.2174/1872208313666181220121400] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Revised: 11/07/2018] [Accepted: 12/25/2018] [Indexed: 06/09/2023]
Abstract
BACKGROUND Arginine deiminase (ADI), an arginine catabolizing enzyme, is considered as an anti-tumor agent for the treatment of arginine auxotrophic cancers. However, some obstacles limit its clinical applications. OBJECTIVE This review will summarize the clinical applications of ADI, from a brief history to its limitations, and will discuss the different ways to deal with the clinical limitations. METHOD The structure analysis, cloning, expression, protein engineering and applications of arginine deiminase enzyme have been explained in this review. CONCLUSION Recent patents on ADI are related to ADI engineering to increase its efficacy for clinical application. The intracellular delivery of ADI and combination therapy seem to be the future strategies in the treatment of arginine auxotrophic cancers. Applying ADIs with optimum features from different sources and or ADI engineering, are promising strategies to improve the clinical application of ADI.
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Affiliation(s)
- Mahboubeh Zarei
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mohammad Reza Rahbar
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mohammad Hossein Morowvat
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
- Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Navid Nezafat
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
- Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Manica Negahdaripour
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
- Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Aydin Berenjian
- School of Engineering, Faculty of Science & Engineering, The University of Waikato, Hamilton, New Zealand
| | - Younes Ghasemi
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
- Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
- Department of Medical Biotechnology, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran
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8
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Zhao C, Ling B, Dong L, Liu Y. Theoretical insights into the protonation states of active site cysteine and citrullination mechanism of Porphyromonas gingivalis peptidylarginine deiminase. Proteins 2017; 85:1518-1528. [PMID: 28486790 DOI: 10.1002/prot.25313] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 04/24/2017] [Accepted: 05/02/2017] [Indexed: 12/29/2022]
Abstract
Porphyromonas gingivalis peptidylarginine deiminase (PPAD) catalyzes the citrullination of peptidylarginine, which plays a critical role in the rheumatoid arthritis (RA) and gene regulation. For a better understanding of citrullination mechanism of PPAD, it is required to establish the protonation states of active site cysteine, which is still a controversial issue for the members of guanidino-group-modifying enzyme superfamily. In this work, we first explored the transformation between the two states: State N (both C351 and H236 are neutral) and State I (both residues exist as a thiolate-imidazolium ion pair), and then investigated the citrullination reaction of peptidylarginine, using a combined QM/MM approach. State N is calculated to be more stable than State I by 8.46 kcal/mol, and State N can transform to State I via two steps of substrate-assisted proton transfer. Citrullination of the peptidylarginine contains deamination and hydrolysis. Starting from State N, the deamination reaction corresponds to an energy barrier of 18.82 kcal/mol. The deprotonated C351 initiates the nucleophilic attack to the substrate, which is the key step for deamination reaction. The hydrolysis reaction contains two chemical steps. Both the deprotonated D238 and H236 can act as the bases to activate the hydrolytic water, which correspond to similar energy barriers (∼17 kcal/mol). On the basis of our calculations, C351, D238, and H236 constitute a catalytic triad, and their protonation states are critical for both the deamination and hydrolysis processes. In view of the sequence similarity, these findings may be shared with human PAD1-PAD4 and other guanidino-group-modifying enzymes. Proteins 2017; 85:1518-1528. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Chenxiao Zhao
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong, 250100, China
| | - Baoping Ling
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong, 250100, China
| | - Lihua Dong
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong, 250100, China.,School of Chemistry and Chemical Engineering, Qilu Normal University, Jinan, Shandong, 250013, China
| | - Yongjun Liu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong, 250100, China
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9
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Miyamoto Y, Eckmann L. Drug Development Against the Major Diarrhea-Causing Parasites of the Small Intestine, Cryptosporidium and Giardia. Front Microbiol 2015; 6:1208. [PMID: 26635732 PMCID: PMC4652082 DOI: 10.3389/fmicb.2015.01208] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 10/16/2015] [Indexed: 12/23/2022] Open
Abstract
Diarrheal diseases are among the leading causes of morbidity and mortality in the world, particularly among young children. A limited number of infectious agents account for most of these illnesses, raising the hope that advances in the treatment and prevention of these infections can have global health impact. The two most important parasitic causes of diarrheal disease are Cryptosporidium and Giardia. Both parasites infect predominantly the small intestine and colonize the lumen and epithelial surface, but do not invade deeper mucosal layers. This review discusses the therapeutic challenges, current treatment options, and drug development efforts against cryptosporidiosis and giardiasis. The goals of drug development against Cryptosporidium and Giardia are different. For Cryptosporidium, only one moderately effective drug (nitazoxanide) is available, so novel classes of more effective drugs are a high priority. Furthermore, new genetic technology to identify potential drug targets and better assays for functional evaluation of these targets throughout the parasite life cycle are needed for advancing anticryptosporidial drug design. By comparison, for Giardia, several classes of drugs with good efficacy exist, but dosing regimens are suboptimal and emerging resistance begins to threaten clinical utility. Consequently, improvements in potency and dosing, and the ability to overcome existing and prevent new forms of drug resistance are priorities in antigiardial drug development. Current work on new drugs against both infections has revealed promising strategies and new drug leads. However, the primary challenge for further drug development is the underlying economics, as both parasitic infections are considered Neglected Diseases with low funding priority and limited commercial interest. If a new urgency in medical progress against these infections can be raised at national funding agencies or philanthropic organizations, meaningful and timely progress is possible in treating and possibly preventing cryptosporidiosis and giardiasis.
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Affiliation(s)
- Yukiko Miyamoto
- Department of Medicine, University of California at San Diego, La Jolla CA, USA
| | - Lars Eckmann
- Department of Medicine, University of California at San Diego, La Jolla CA, USA
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10
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Kaur B, Kaur R. Purification of a dimeric arginine deiminase from Enterococcus faecium GR7 and study of its anti-cancerous activity. Protein Expr Purif 2015; 125:53-60. [PMID: 26363115 DOI: 10.1016/j.pep.2015.09.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 09/07/2015] [Accepted: 09/08/2015] [Indexed: 10/23/2022]
Abstract
The arginine deiminase (ADI, E.C 3.5.3.6) - a key enzyme of ADI pathway of Enterococcus faecium GR7 was purified to homogeneity. A sequential purification strategy involving ammonium sulfate fractionation, molecular sieve followed by Sephadex G-100 gel filtration was applied to the crude culture filtrate to obtain a pure enzyme preparation. The enzyme was purified with a fold of 16.92 and showed a final specific activity of 76.65IU/mg with a 49.17% yield. The dimeric ADI has a molecular mass of about 94,364.929Da, and comprises of hetrodimers of 49.1kDa and 46.5kDa as determined by MALDI-TOF and PAGE analysis. To assess anti-cancerous activity of ADI by MTT assay was carried out against cancer cell lines (MCF-7, Sp2/0-Ag14 and Hep-G2). Purified ADI exhibited the most profound antiproliferative activity against Hep-G2 cells; with half-maximal inhibitory concentration (IC50) of 1.95μg/ml. Purified ADI from E. faecium GR7 was observed to induce apoptosis in the Hep-G2 cells by DNA fragmentation assay. Our findings suggest the possibility of a future use of ADI from E. faecium GR7 as a potential anticancer drug.
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Affiliation(s)
- Baljinder Kaur
- Department of Biotechnology, Punjabi University, Patiala 147002, Punjab, India.
| | - Rajinder Kaur
- Department of Biotechnology, Punjabi University, Patiala 147002, Punjab, India
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11
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Trejo-Soto PJ, Aguayo-Ortiz R, Yépez-Mulia L, Hernández-Campos A, Medina-Franco JL, Castillo R. Insights into the structure and inhibition of Giardia intestinalis arginine deiminase: homology modeling, docking, and molecular dynamics studies. J Biomol Struct Dyn 2015; 34:732-48. [PMID: 26017138 DOI: 10.1080/07391102.2015.1051115] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Giardia intestinalis arginine deiminase (GiADI) is an important metabolic enzyme involved in the energy production and defense of this protozoan parasite. The lack of this enzyme in the human host makes GiADI an attractive target for drug design against G. intestinalis. One approach in the design of inhibitors of GiADI could be computer-assisted studies of its crystal structure, such as docking; however, the required crystallographic structure of the enzyme still remains unresolved. Because of its relevance, in this work, we present a three-dimensional structure of GiADI obtained from its amino acid sequence using the homology modeling approximation. Furthermore, we present an approximation of the most stable dimeric structure of GiADI identified through molecular dynamics simulation studies. An in silico analysis of druggability using the structure of GiADI was carried out in order to know if it is a good target for design and optimization of selective inhibitors. Potential GiADI inhibitors were identified by docking of a set of 3196 commercial and 19 in-house benzimidazole derivatives, and molecular dynamics simulation studies were used to evaluate the stability of the ligand-enzyme complexes.
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Affiliation(s)
- Pedro Josué Trejo-Soto
- a Facultad de Química, Departamento de Farmacia , Universidad Nacional Autónoma de México , México, DF 04510 , Mexico
| | - Rodrigo Aguayo-Ortiz
- a Facultad de Química, Departamento de Farmacia , Universidad Nacional Autónoma de México , México, DF 04510 , Mexico
| | - Lilián Yépez-Mulia
- b Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, IMSS , México, DF 06720 , Mexico
| | - Alicia Hernández-Campos
- a Facultad de Química, Departamento de Farmacia , Universidad Nacional Autónoma de México , México, DF 04510 , Mexico
| | - José Luis Medina-Franco
- a Facultad de Química, Departamento de Farmacia , Universidad Nacional Autónoma de México , México, DF 04510 , Mexico
| | - Rafael Castillo
- a Facultad de Química, Departamento de Farmacia , Universidad Nacional Autónoma de México , México, DF 04510 , Mexico
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Ansell BRE, McConville MJ, Ma'ayeh SY, Dagley MJ, Gasser RB, Svärd SG, Jex AR. Drug resistance in Giardia duodenalis. Biotechnol Adv 2015; 33:888-901. [PMID: 25922317 DOI: 10.1016/j.biotechadv.2015.04.009] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 04/21/2015] [Accepted: 04/21/2015] [Indexed: 02/07/2023]
Abstract
Giardia duodenalis is a microaerophilic parasite of the human gastrointestinal tract and a major contributor to diarrheal and post-infectious chronic gastrointestinal disease world-wide. Treatment of G. duodenalis infection currently relies on a small number of drug classes. Nitroheterocyclics, in particular metronidazole, have represented the front line treatment for the last 40 years. Nitroheterocyclic-resistant G. duodenalis have been isolated from patients and created in vitro, prompting considerable research into the biomolecular mechanisms of resistance. These compounds are redox-active and are believed to damage proteins and DNA after being activated by oxidoreductase enzymes in metabolically active cells. In this review, we explore the molecular phenotypes of nitroheterocyclic-resistant G. duodenalis described to date in the context of the protist's unusual glycolytic and antioxidant systems. We propose that resistance mechanisms are likely to extend well beyond currently described resistance-associated enzymes (i.e., pyruvate ferredoxin oxidoreductases and nitroreductases), to include NAD(P)H- and flavin-generating pathways, and possibly redox-sensitive epigenetic regulation. Mechanisms that allow G. duodenalis to tolerate oxidative stress may lead to resistance against both oxygen and nitroheterocyclics, with implications for clinical control. The present review highlights the potential for systems biology tools and advanced bioinformatics to further investigate the multifaceted mechanisms of nitroheterocyclic resistance in this important pathogen.
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Affiliation(s)
- Brendan R E Ansell
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Cnr Park Dr and Flemington Rd, Parkville, VIC 3010, Australia.
| | - Malcolm J McConville
- Bio21 Institute, University of Melbourne, 30 Flemington Rd, Parkville, VIC 3010, Australia
| | - Showgy Y Ma'ayeh
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Box 596, SE-751 24 Uppsala, Sweden
| | - Michael J Dagley
- Bio21 Institute, University of Melbourne, 30 Flemington Rd, Parkville, VIC 3010, Australia
| | - Robin B Gasser
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Cnr Park Dr and Flemington Rd, Parkville, VIC 3010, Australia
| | - Staffan G Svärd
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Box 596, SE-751 24 Uppsala, Sweden
| | - Aaron R Jex
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Cnr Park Dr and Flemington Rd, Parkville, VIC 3010, Australia
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Regulation of the arginine deiminase system by ArgR2 interferes with arginine metabolism and fitness of Streptococcus pneumoniae. mBio 2014; 5:mBio.01858-14. [PMID: 25538192 PMCID: PMC4278536 DOI: 10.1128/mbio.01858-14] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus pneumoniae is auxotrophic for arginine, and molecular analysis of the pneumococcal genome showed that the gene encoding an arginine-ornithine antiporter (ArcD) is organized in a cluster together with the arcABC genes encoding the arginine deiminase system (ADS) of pneumococci. The ADS consists of the arginine deiminase (AD), the catabolic ornithine carbamoyltransferase (cOCT), and the carbamate kinase (CK). Pneumococcal genomes contain three ArgR-type regulators (ArgR1, ArgR2, and AhrC) that are supposed to be involved in the regulation of arginine metabolism. Here, we identified ArgR2 of TIGR4 as the regulator of the ADS and ArcD. ArgR2 binds to promoter sequences of the arc operon, and the deficiency of ArgR2 in TIGR4 abrogates expression of the ADS, including the arginine-ornithine antiporter ArcD. Intranasal infection of mice and real-time bioimaging revealed that deletion of the arcABCDT genes attenuates TIGR4. However, the acute-pneumonia model and coinfection experiments indicated that the arginine-ornithine antiporter ArcD is essential to maintain fitness, while the deficiency of ADS enzymes has a minor impact on pneumococcal fitness under in vivo conditions. Strikingly, argR2 mutant TIGR4 outcompeted the wild type in the respiratory tract, suggesting an increase in fitness and further regulatory functions of ArgR2. In contrast to TIGR4, other pneumococci, such as D39, lacking expression of ArgR2, constitutively express the ADS with a truncated nonfunctional AD. On the basis of these results, we propose that the arginine-ornithine antiporter is essential to maintain pneumococcal fitness and that the genes of the ADS cluster are positively regulated in a strain-specific manner by ArgR2. Pneumococci are the major etiologic agents of community-acquired pneumonia, causing more than 1.5 million deaths annually worldwide. These versatile pathogens are highly adapted to the nutrients provided by the host niches encountered. Physiological fitness is of major importance for colonization of the nasopharyngeal cavity and dissemination during invasive infections. This work identifies the regulator ArgR2 as the activator of the S. pneumoniae TIGR4 ADS and the arginine-ornithine transporter ArcD, which is needed for uptake of the essential amino acid arginine. Although ArgR2 activates ArcD expression and uptake of arginine is required to maintain pneumococcal fitness, the deficiency of ArgR2 increases TIGR4 virulence under in vivo conditions, suggesting that other factors regulated by ArgR2 counterbalance the reduced uptake of arginine by ArcD. Thus, this work illustrates that the physiological homeostasis of pneumococci is complex and that ArgR2 plays a key role in maintaining bacterial fitness.
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Wang Y, Li YZ. Cultivation to improve in vivo solubility of overexpressed arginine deiminases in Escherichia coli and the enzyme characteristics. BMC Biotechnol 2014; 14:53. [PMID: 24908259 PMCID: PMC4072490 DOI: 10.1186/1472-6750-14-53] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 06/03/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Overexpression of foreign genes in Escherichia coli cells is an efficient means to obtain recombinant proteins. The technique is, however, often hampered by misfolding, degradation, aggregation and formation in inclusion bodies of products. RESULTS In this study, we reported that in vivo solubility of overexpressed arginine deiminases (ADI) improved by changing the cultivation conditions. ADI is enzymes that convert L-arginine to L-citrulline. After codon optimization, we synthesized the ADI gene of Pseudomonas putida and constructed it for overexpression in E. coli cells. The rADI products were mainly in inclusion body forms. We performed a series of optimization to enhance solubility of the protein. Co-expression with the GroES-GroEL chaperone team increased approximately 5-fold of the rADI activity. In addition the combination of L-arginine and D-glucose in the Luria-Bertani (LB) growth medium further increased the total activity to about 15 times. Separate L-arginine and D-glucose or the addition of other saccharides or amino acids had no such effects. The solubilization effects of the combination of L-arginine and D-glucose were further confirmed in the overexpression of another ADI from Listeria welshimeri. The enzymatic and conversion characteristics of the rADI products were further determined. CONCLUSIONS Combined addition of L-arginine and D-glucose in the LB medium significantly improved in vivo solubility of rADI proteins. The present study suggested a new strategy to increase the solubilization of overexpressed recombinant proteins in E. coli cells.
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Affiliation(s)
| | - Yue-Zhong Li
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan 250100, P, R, China.
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Hering S, Sieg A, Kreikemeyer B, Fiedler T. Kinetic characterization of arginine deiminase and carbamate kinase from Streptococcus pyogenes M49. Protein Expr Purif 2013; 91:61-8. [PMID: 23867361 DOI: 10.1016/j.pep.2013.07.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 06/27/2013] [Accepted: 07/08/2013] [Indexed: 11/28/2022]
Abstract
Streptococcus pyogenes (group A Streptococcus, GAS) is an important human pathogen causing mild superficial infections of skin and mucous membranes, but also life-threatening systemic diseases. S. pyogenes and other prokaryotic organisms use the arginine deiminase system (ADS) for survival in acidic environments. In this study, the arginine deiminase (AD), and carbamate kinase (CK) from S. pyogenes M49 strain 591 were heterologously expressed in Escherichia coli DH5α, purified, and kinetically characterized. AD and CK from S. pyogenes M49 share high amino acid sequence similarity with the respective enzymes from Lactococcus lactis subsp. lactis IL1403 (45.6% and 53.5% identical amino acids) and Enterococcus faecalis V583 (66.8% and 66.8% identical amino acids). We found that the arginine deiminase of S. pyogenes is not allosterically regulated by the intermediates and products of the arginine degradation (e.g., ATP, citrulline, carbamoyl phosphate). The Km and Vmax values for arginine were 1.13±0.12mM (mean±SD) and 1.51±0.07μmol/min/mg protein. The carbamate kinase is inhibited by ATP but unaffected by arginine and citrulline. The Km and Vmax values for ADP were 0.72±0.08mM and 1.10±0.10μmol/min/mg protein and the Km for carbamoyl phosphate was 0.65±0.07mM. The optimum pH and temperature for both enzymes were 6.5 and 37°C, respectively.
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Affiliation(s)
- Silvio Hering
- Rostock University Medical Centre, Institute of Medical Microbiology, Virology, and Hygiene, Schillingallee 70, 18057 Rostock, Germany
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Gallego P, Planell R, Benach J, Querol E, Perez-Pons JA, Reverter D. Structural characterization of the enzymes composing the arginine deiminase pathway in Mycoplasma penetrans. PLoS One 2012; 7:e47886. [PMID: 23082227 PMCID: PMC3474736 DOI: 10.1371/journal.pone.0047886] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Accepted: 09/24/2012] [Indexed: 11/19/2022] Open
Abstract
The metabolism of arginine towards ATP synthesis has been considered a major source of energy for microorganisms such as Mycoplasma penetrans in anaerobic conditions. Additionally, this pathway has also been implicated in pathogenic and virulence mechanism of certain microorganisms, i.e. protection from acidic stress during infection. In this work we present the crystal structures of the three enzymes composing the gene cluster of the arginine deiminase pathway from M. penetrans: arginine deiminase (ADI), ornithine carbamoyltransferase (OTC) and carbamate kinase (CK). The arginine deiminase (ADI) structure has been refined to 2.3 Å resolution in its apo-form, displaying an "open" conformation of the active site of the enzyme in comparison to previous complex structures with substrate intermediates. The active site pocket of ADI is empty, with some of the catalytic and binding residues far from their active positions, suggesting major conformational changes upon substrate binding. Ornithine carbamoyltransferase (OTC) has been refined in two crystal forms at 2.5 Å and 2.6 Å resolution, respectively, both displaying an identical dodecameric structure with a 23-point symmetry. The dodecameric structure of OTC represents the highest level of organization in this protein family and in M.penetrans it is constituted by a novel interface between the four catalytic homotrimers. Carbamate kinase (CK) has been refined to 2.5 Å resolution and its structure is characterized by the presence of two ion sulfates in the active site, one in the carbamoyl phosphate binding site and the other in the β-phosphate ADP binding pocket of the enzyme. The CK structure also shows variations in some of the elements that regulate the catalytic activity of the enzyme. The relatively low number of metabolic pathways and the relevance in human pathogenesis of Mycoplasma penetrans places the arginine deiminase pathway enzymes as potential targets to design specific inhibitors against this human parasite.
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Affiliation(s)
- Pablo Gallego
- Institut de Biotecnologia i de Biomedicina and Departament de Bioquímica i de Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Raquel Planell
- Institut de Biotecnologia i de Biomedicina and Departament de Bioquímica i de Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Jordi Benach
- Experiments Division, ALBA Synchrotron Light Source, Barcelona, Spain
| | - Enrique Querol
- Institut de Biotecnologia i de Biomedicina and Departament de Bioquímica i de Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Josep A. Perez-Pons
- Institut de Biotecnologia i de Biomedicina and Departament de Bioquímica i de Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - David Reverter
- Institut de Biotecnologia i de Biomedicina and Departament de Bioquímica i de Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
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Plasmid vectors for proteomic analyses in Giardia: purification of virulence factors and analysis of the proteasome. EUKARYOTIC CELL 2012; 11:864-73. [PMID: 22611020 DOI: 10.1128/ec.00092-12] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In recent years, proteomics has come of age with the development of efficient tools for purification, identification, and characterization of gene products predicted by genome projects. The intestinal protozoan Giardia intestinalis can be transfected, but there is only a limited set of vectors available, and most of them are not user friendly. This work delineates the construction of a suite of cassette-based expression vectors for use in Giardia. Expression is provided by the strong constitutive ornithine carbamoyltransferase (OCT) promoter, and tagging is possible in both N- and C-terminal configurations. Taken together, the vectors are capable of providing protein localization and production of recombinant proteins, followed by efficient purification by a novel affinity tag combination, streptavidin binding peptide-glutathione S-transferase (SBP-GST). The option of removing the tags from purified proteins was provided by the inclusion of a PreScission protease site. The efficiency and feasibility of producing and purifying endogenous recombinant Giardia proteins with the developed vectors was demonstrated by the purification of active recombinant arginine deiminase (ADI) and OCT from stably transfected trophozoites. Moreover, we describe the tagging, purification by StrepTactin affinity chromatography, and compositional analysis by mass spectrometry of the G. intestinalis 26S proteasome by employing the Strep II-FLAG-tandem affinity purification (SF-TAP) tag. This is the first report of efficient production and purification of recombinant proteins in and from Giardia, which will allow the study of specific parasite proteins and protein complexes.
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Nocadello S, Swennen EF. The new pLAI (lux regulon based auto-inducible) expression system for recombinant protein production in Escherichia coli. Microb Cell Fact 2012; 11:3. [PMID: 22222111 PMCID: PMC3274441 DOI: 10.1186/1475-2859-11-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 01/05/2012] [Indexed: 11/26/2022] Open
Abstract
Background After many years of intensive research, it is generally assumed that no universal expression system can exist for high-level production of a given recombinant protein. Among the different expression systems, the inducible systems are the most popular for their tight regulation. However, induction is in many cases less favorable due to the high cost and/or toxicity of inducers, incompatibilities with industrial scale-up or detrimental growth conditions. Expression systems using autoinduction (or self-induction) prove to be extremely versatile allowing growth and induction of recombinant proteins without the need to monitor cell density or add inducer. Unfortunately, almost all the actual auto inducible expression systems need endogenous or induced metabolic changes during the growth to trigger induction, both frequently linked to detrimental condition to cell growth. In this context, we use a simple modular approach for a cell density-based genetic regulation in order to assemble an autoinducible recombinant protein expression system in E. coli. Result The newly designed pLAI expression system places the expression of recombinant proteins in Escherichia coli under control of the regulatory genes of the lux regulon of Vibrio fischeri's Quorum Sensing (QS) system. The pLAI system allows a tight regulation of the recombinant gene allowing a negligible basal expression and expression only at high cell density. Sequence optimization of regulative genes of QS of V. fischeri for expression in E. coli upgraded the system to high level expression. Moreover, partition of regulative genes between the plasmid and the host genome and introduction of a molecular safety lock permitted tighter control of gene expression. Conclusion Coupling gene expression to cell density using cell-to-cell communication provides a promising approach for recombinant protein production. The system allows the control of expression of the target recombinant gene independently from external inducers or drastic changes in metabolic conditions and enabling tight regulation of expression.
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Abstract
PURPOSE OF REVIEW Giardiasis is one of the most common causes of diarrheal disease worldwide, yet existing antimicrobial therapies are not always effective and drug resistance occurs in vivo and in vitro. The review focuses on recent advances in the development of new antigiardial drug candidates. RECENT FINDINGS Modification of existing drug leads is a major strategy to develop new high-potency drugs. Complex derivatives of 5-nitroimidazole, the core structure of the most commonly used antigiardial drug, metronidazole, have shown significantly improved activities against Giardia and the ability to overcome metronidazole resistance. Derivatives of benzimidazole, the structural core of the effective antigiardial albendazole, are also exhibiting promising new activities. Beyond lead modifications, several new classes of antigiardial drug candidates have recently been identified by high-throughput screening of large compound libraries, and first efforts have been reported on the development of drugs tailored to known molecular targets in Giardia. SUMMARY The pipeline of new antigiardial drug candidates has significantly expanded over the last few years, but this expansion has so far not been accompanied by demonstration of efficacy in animal models or by a clear understanding of the action mechanisms, particularly in regard to new nitro antimicrobials. Many challenges are still to be expected before clinical utility of new antigiardial drugs can be established.
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20
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Ke Z, Guo H. Ab initio QM/MM free-energy studies of arginine deiminase catalysis: the protonation state of the Cys nucleophile. J Phys Chem B 2011; 115:3725-33. [PMID: 21395290 PMCID: PMC3070061 DOI: 10.1021/jp200843s] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The first step of the hydrolytic deimination of L-arginine catalyzed by arginine deiminase is examined using ab initio quantum mechanical/molecular mechanical molecular dynamics simulations. Two possible protonation states of the nucleophilic Cys406 residue were investigated, and the corresponding activation free energies were obtained via umbrella sampling. Our calculations indicated a reaction free-energy barrier of 21.3 kcal/mol for the neutral cysteine, which is in reasonably good agreement with the experimental k(cat) value of 6.3 s(-1), i.e., a barrier of 16.7 kcal/mol. On the other hand, the deprotonated Cys nucleophile yields a free-energy barrier of 6.7 kcal/mol, much lower than the experimental result. The reaction free-energy barriers along with other data suggest that the Cys nucleophile is dominated by its protonated state in the Michaelis complex, and the reaction barrier corresponds largely to its deprotonation.
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Affiliation(s)
- Zhihong Ke
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico, 87131
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico, 87131
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21
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The transcriptional response to encystation stimuli in Giardia lamblia is restricted to a small set of genes. EUKARYOTIC CELL 2010; 9:1566-76. [PMID: 20693303 DOI: 10.1128/ec.00100-10] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The protozoan parasite Giardia lamblia undergoes stage differentiation in the small intestine of the host to an environmentally resistant and infectious cyst. Encystation involves the secretion of an extracellular matrix comprised of cyst wall proteins (CWPs) and a β(1-3)-GalNAc homopolymer. Upon the induction of encystation, genes coding for CWPs are switched on, and mRNAs coding for a Myb transcription factor and enzymes involved in cyst wall glycan synthesis are upregulated. Encystation in vitro is triggered by several protocols, which call for changes in bile concentrations or availability of lipids, and elevated pH. However, the conditions for induction are not standardized and we predicted significant protocol-specific side effects. This makes reliable identification of encystation factors difficult. Here, we exploited the possibility of inducing encystation with two different protocols, which we show to be equally effective, for a comparative mRNA profile analysis. The standard encystation protocol induced a bipartite transcriptional response with surprisingly minor involvement of stress genes. A comparative analysis revealed a core set of only 18 encystation genes and showed that a majority of genes was indeed upregulated as a side effect of inducing conditions. We also established a Myb binding sequence as a signature motif in encystation promoters, suggesting coordinated regulation of these factors.
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22
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Novel, versatile, and tightly regulated expression system for Escherichia coli strains. Appl Environ Microbiol 2010; 76:5058-66. [PMID: 20562288 DOI: 10.1128/aem.00413-10] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel tightly regulated gene expression system was developed for Escherichia coli by applying the regulatory elements of the Pseudomonas putida F1 cym and cmt operons to control target gene expression at the transcriptional level by using p-isopropylbenzoate (cumate) as an inducer. This novel expression system, referred to as the cumate gene switch, includes a specific expression vector, pNEW, that contains a partial T5 phage promoter combined with the Pseudomonas-based synthetic operator and the cymR repressor protein-encoding gene designed to express constitutively in the host strain. The induction of transcription relies on the addition of the exogenous inducer (cumate), which is nontoxic to the culture, water soluble, and inexpensive. The characteristics and potential of the expression system were determined. Using flow cytometry and fed-batch fermentations, we have shown that, with the newly developed cumate-regulated system, (i) higher recombinant product yields can be obtained than with the pET (isopropyl-beta-D-thiogalactopyranoside [IPTG])-induced expression system, (ii) expression is tightly regulated, (iii) addition of cumate quickly results in a fully induced and homogenous protein-expressing population in contrast to the bimodal expression profile of an IPTG-induced population, (iv) expression can be modulated by varying the cumate concentration, and (v) the cumate-induced population remains induced and fully expressing even at 8 h following induction, resulting in high yields of the target protein Furthermore, the cumate gene switch described in this article is applicable to a wide range of E. coli strains.
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Galkin A, Kulakova L, Wu R, Nash TE, Dunaway-Mariano D, Herzberg O. X-ray structure and characterization of carbamate kinase from the human parasite Giardia lamblia. Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 66:386-90. [PMID: 20383005 PMCID: PMC2852327 DOI: 10.1107/s1744309110004665] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Accepted: 02/05/2010] [Indexed: 11/10/2022]
Abstract
Carbamate kinase catalyzes the reversible conversion of carbamoyl phosphate and ADP to ATP and ammonium carbamate, which is hydrolyzed to ammonia and carbonate. The three-dimensional structure of carbamate kinase from the human parasite Giardia lamblia (glCK) has been determined at 3 A resolution. The crystals belonged to the monoclinic space group P2(1), with unit-cell parameters a = 69.77, b = 85.41, c = 102.1 A, beta = 106.8 degrees . The structure was refined to a final R factor of 0.227. The essentiality of glCK together with its absence in humans makes the enzyme an attractive candidate for anti-Giardia drug development. Steady-state kinetic rate constants have been determined. The k(cat) for ATP formation is 319 +/- 9 s(-1). The K(m) values for carbamoyl phosphate and ADP are 85 +/- 6 and 70 +/- 5 microM, respectively. The structure suggests that three invariant lysine residues (Lys131, Lys216 and Lys278) may be involved in the binding of substrates and phosphoryl transfer. The structure of glCK reveals that a glycerol molecule binds in the likely carbamoyl phosphate-binding site.
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Affiliation(s)
- Andrey Galkin
- W. M. Keck Laboratory for Structural Biology, Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland, USA
| | - Liudmila Kulakova
- W. M. Keck Laboratory for Structural Biology, Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland, USA
| | - Rui Wu
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico, USA
| | - Theodore E. Nash
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Debra Dunaway-Mariano
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico, USA
| | - Osnat Herzberg
- W. M. Keck Laboratory for Structural Biology, Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland, USA
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Galkin A, Kulakova L, Wu R, Gong M, Dunaway-Mariano D, Herzberg O. X-ray structure and kinetic properties of ornithine transcarbamoylase from the human parasite Giardia lamblia. Proteins 2009; 76:1049-53. [PMID: 19507245 DOI: 10.1002/prot.22469] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Andrey Galkin
- W.M. Keck Laboratory for Structural Biology, Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland, USA
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An efficient method for N-acetyl-d-neuraminic acid production using coupled bacterial cells with a safe temperature-induced system. Appl Microbiol Biotechnol 2009; 86:481-9. [DOI: 10.1007/s00253-009-2302-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Revised: 10/07/2009] [Accepted: 10/07/2009] [Indexed: 10/20/2022]
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26
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Li Z, Kulakova L, Li L, Galkin A, Zhao Z, Nash TE, Mariano PS, Herzberg O, Dunaway-Mariano D. Mechanisms of catalysis and inhibition operative in the arginine deiminase from the human pathogen Giardia lamblia. Bioorg Chem 2009; 37:149-61. [PMID: 19640561 DOI: 10.1016/j.bioorg.2009.06.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Revised: 06/06/2009] [Accepted: 06/08/2009] [Indexed: 11/27/2022]
Abstract
Giardia lamblia arginine deiminase (GlAD), the topic of this paper, belongs to the hydrolase branch of the guanidine-modifying enzyme superfamily, whose members employ Cys-mediated nucleophilic catalysis to promote deimination of l-arginine and its naturally occurring derivatives. G. lamblia is the causative agent in the human disease giardiasis. The results of RNAi/antisense RNA gene-silencing studies reported herein indicate that GlAD is essential for G. lamblia trophozoite survival and thus, a potential target for the development of therapeutic agents for the treatment of giardiasis. The homodimeric recombinant protein was prepared in Escherichia coli for in-depth biochemical characterization. The 2-domain GlAD monomer consists of a N-terminal domain that shares an active site structure (depicted by an insilico model) and kinetic properties (determined by steady-state and transient state kinetic analysis) with its bacterial AD counterparts, and a C-terminal domain of unknown fold and function. GlAD was found to be active over a wide pH range and to accept l-arginine, l-arginine ethyl ester, N(alpha)-benzoyl-l-arginine, and N(omega)-amino-l-arginine as substrates but not agmatine, l-homoarginine, N(alpha)-benzoyl-l-arginine ethyl ester or a variety of arginine-containing peptides. The intermediacy of a Cys424-alkylthiouronium ion covalent enzyme adduct was demonstrated and the rate constants for formation (k(1)=80s(-1)) and hydrolysis (k(2)=35s(-1)) of the intermediate were determined. The comparatively lower value of the steady-state rate constant (k(cat)=2.6s(-1)), suggests that a step following citrulline formation is rate-limiting. Inhibition of GlAD using Cys directed agents was briefly explored. S-Nitroso-l-homocysteine was shown to be an active site directed, irreversible inhibitor whereas N(omega)-cyano-l-arginine did not inhibit GlAD but instead proved to be an active site directed, irreversible inhibitor of the Bacillus cereus AD.
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Affiliation(s)
- Zhimin Li
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM 87131, USA
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Deamination process in the formation of a copper(II) complex with glutamic acid and a new ligand derived from guanidinoacetic acid: Synthesis, characterization, and molecular modeling studies. Polyhedron 2008. [DOI: 10.1016/j.poly.2008.04.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Li L, Li Z, Wang C, Xu D, Mariano PS, Guo H, Dunaway-Mariano D. The Electrostatic Driving Force for Nucleophilic Catalysis in l-Arginine Deiminase: A Combined Experimental and Theoretical Study. Biochemistry 2008; 47:4721-32. [DOI: 10.1021/bi7023496] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ling Li
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Zhimin Li
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Canhui Wang
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Dingguo Xu
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Patrick S. Mariano
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Debra Dunaway-Mariano
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
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Release of metabolic enzymes by Giardia in response to interaction with intestinal epithelial cells. Mol Biochem Parasitol 2008; 159:85-91. [PMID: 18359106 DOI: 10.1016/j.molbiopara.2008.02.005] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2007] [Revised: 01/24/2008] [Accepted: 02/07/2008] [Indexed: 11/20/2022]
Abstract
Giardia lamblia, an important cause of diarrheal disease, resides in the small intestinal lumen in close apposition to epithelial cells. Since the disease mechanisms underlying giardiasis are poorly understood, elucidating the specific interactions of the parasite with the host epithelium is likely to provide clues to understanding the pathogenesis. Here we tested the hypothesis that contact of Giardia lamblia with intestinal epithelial cells might lead to release of specific proteins. Using established co-culture models, intestinal ligated loops and a proteomics approach, we identified three G. lamblia proteins (arginine deiminase, ornithine carbamoyl transferase and enolase), previously recognized as immunodominant antigens during acute giardiasis. Release was stimulated by cell-cell interactions, since only small amounts of arginine deiminase and enolase were detected in the medium after culturing of G. lamblia alone. The secreted G. lamblia proteins were localized to the cytoplasm and the inside of the plasma membrane of trophozoites. Furthermore, in vitro studies with recombinant arginine deiminase showed that the secreted Giardia proteins can disable host innate immune factors such as nitric oxide production. These results indicate that contact of Giardia with epithelial cells triggers metabolic enzyme release, which might facilitate effective colonization of the human small intestine.
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Li L, Li Z, Chen D, Lu X, Feng X, Wright EC, Solberg NO, Dunaway-Mariano D, Mariano PS, Galkin A, Kulakova L, Herzberg O, Green-Church KB, Zhang L. Inactivation of microbial arginine deiminases by L-canavanine. J Am Chem Soc 2008; 130:1918-31. [PMID: 18205354 DOI: 10.1021/ja0760877] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Arginine deiminase (ADI) catalyzes the hydrolytic conversion of L-arginine to ammonia and L-citrulline as part of the energy-producing L-arginine degradation pathway. The chemical mechanism for ADI catalysis involves initial formation and subsequent hydrolysis of a Cys-alkylthiouronium ion intermediate. The structure of the Pseudomonas aeruginosa ADI-(L-arginine) complex guided the design of arginine analogs that might react with the ADIs to form inactive covalent adducts during catalytic turnover. One such candidate is L-canavanine, in which an N-methylene of L-arginine is replaced by an N-O. This substance was shown to be a slow substrate-producing O-ureido-L-homoserine. An in depth kinetic and mass spectrometric analysis of P. aeruginosa ADI inhibition by L-canavanine showed that two competing pathways are followed that branch at the Cys-alkylthiouronium ion intermediate. One pathway leads to direct formation of O-ureido-L-homoserine via a reactive thiouronium intermediate. The other pathway leads to an inactive form of the enzyme, which was shown by chemical model and mass spectrometric studies to be a Cys-alkylisothiourea adduct. This adduct undergoes slow hydrolysis to form O-ureido-L-homoserine and regenerated enzyme. In contrast, kinetic and mass spectrometric investigations demonstrate that the Cys-alkylthiouronium ion intermediate formed in the reaction of L-canavanine with Bacillus cereus ADI partitions between the product forming pathway (O-ureido-L-homoserine and free enzyme) and an inactivation pathway that leads to a stable Cys-alkylthiocarbamate adduct. The ADIs from Escherichia coli, Burkholderia mallei, and Giardia intestinalis were examined in order to demonstrate the generality of the L-canavanine slow substrate inhibition and to distinguish the kinetic behavior that defines the irreversible inhibition observed with the B. cereus ADI from the time controlled inhibition observed with the P. aeruginosa, E. coli, B. mallei, and G. intestinalis ADIs.
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Affiliation(s)
- Ling Li
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
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31
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Arginine deiminase, a potential anti-tumor drug. Cancer Lett 2008; 261:1-11. [PMID: 18179862 DOI: 10.1016/j.canlet.2007.11.038] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Revised: 11/21/2007] [Accepted: 11/23/2007] [Indexed: 11/24/2022]
Abstract
Arginine deiminase (ADI; EC 3.5.3.6), an arginine-degrading enzyme, has been studied as a potential anti-tumor drug for the treatment of arginine-auxotrophic tumors, such as hepatocellular carcinomas (HCCs) and melanomas. Studies with human lymphatic leukemia cell lines further suggest that ADI is a potential anti-angiogenic agent and is effective in the treatment of leukemia. For instance ADI-PEG-20, patented by Pheonix Pharmacologic Inc., is currently in clinical trials for the treatment of HCC (Phase II/III) and melanoma (Phase I/II). This review summarizes results on recombinant expression, structural analysis, PEG (polyethylene glycerol) modification, in vivo anti-cancer activities, and clinical studies of ADI. Discussions on heterogeneous expression of ADI, directed evolution for improving enzymatic properties, and HSA-fusion for increased in vivo activity conclude this review.
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Schriek S, Rückert C, Staiger D, Pistorius EK, Michel KP. Bioinformatic evaluation of L-arginine catabolic pathways in 24 cyanobacteria and transcriptional analysis of genes encoding enzymes of L-arginine catabolism in the cyanobacterium Synechocystis sp. PCC 6803. BMC Genomics 2007; 8:437. [PMID: 18045455 PMCID: PMC2242806 DOI: 10.1186/1471-2164-8-437] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Accepted: 11/28/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND So far very limited knowledge exists on L-arginine catabolism in cyanobacteria, although six major L-arginine-degrading pathways have been described for prokaryotes. Thus, we have performed a bioinformatic analysis of possible L-arginine-degrading pathways in cyanobacteria. Further, we chose Synechocystis sp. PCC 6803 for a more detailed bioinformatic analysis and for validation of the bioinformatic predictions on L-arginine catabolism with a transcript analysis. RESULTS We have evaluated 24 cyanobacterial genomes of freshwater or marine strains for the presence of putative L-arginine-degrading enzymes. We identified an L-arginine decarboxylase pathway in all 24 strains. In addition, cyanobacteria have one or two further pathways representing either an arginase pathway or L-arginine deiminase pathway or an L-arginine oxidase/dehydrogenase pathway. An L-arginine amidinotransferase pathway as a major L-arginine-degrading pathway is not likely but can not be entirely excluded. A rather unusual finding was that the cyanobacterial L-arginine deiminases are substantially larger than the enzymes in non-photosynthetic bacteria and that they are membrane-bound. A more detailed bioinformatic analysis of Synechocystis sp. PCC 6803 revealed that three different L-arginine-degrading pathways may in principle be functional in this cyanobacterium. These are (i) an L-arginine decarboxylase pathway, (ii) an L-arginine deiminase pathway, and (iii) an L-arginine oxidase/dehydrogenase pathway. A transcript analysis of cells grown either with nitrate or L-arginine as sole N-source and with an illumination of 50 mumol photons m-2 s-1 showed that the transcripts for the first enzyme(s) of all three pathways were present, but that the transcript levels for the L-arginine deiminase and the L-arginine oxidase/dehydrogenase were substantially higher than that of the three isoenzymes of L-arginine decarboxylase. CONCLUSION The evaluation of 24 cyanobacterial genomes revealed that five different L-arginine-degrading pathways are present in the investigated cyanobacterial species. In Synechocystis sp. PCC 6803 an L-arginine deiminase pathway and an L-arginine oxidase/dehydrogenase pathway represent the major pathways, while the L-arginine decarboxylase pathway most likely only functions in polyamine biosynthesis. The transcripts encoding the enzymes of the two major pathways were constitutively expressed with the exception of the transcript for the carbamate kinase, which was substantially up-regulated in cells grown with L-arginine.
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Affiliation(s)
- Sarah Schriek
- Lehrstuhl für Molekulare Zellphysiologie, Universität Bielefeld, Universitätsstr, 25, D-33615 Bielefeld, Germany.
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33
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Wang C, Xu D, Zhang L, Xie D, Guo H. Molecular Dynamics and Density Functional Studies of Substrate Binding and Catalysis of Arginine Deiminase. J Phys Chem B 2007; 111:3267-73. [PMID: 17388453 DOI: 10.1021/jp067541g] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The active-site dynamics of arginine deiminase (ADI) complexed with the arginine substrate are investigated with ns molecular dynamics for the wildtype ADI and several mutants. It is shown that the substrate is held in the active site by an extensive hydrogen bond network, which may be weakened by substitution of active-site residues. In addition, the initial step of the catalysis is explored in several truncated active-site models with density functional theory. Evidence is presented in support of the hypothesis that the nucleophilic attack of the ADI Cys thiol at the guanidino carbon of the substrate is initiated by substrate-mediated proton transfer to a His residue in the catalytic triad (Cys-His-Glu). In addition, the active-site residues are found to strongly influence the reaction profile, consistent with their important role in catalysis.
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Affiliation(s)
- Canhui Wang
- Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131, USA
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34
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Davids BJ, Palm JED, Housley MP, Smith JR, Andersen YS, Martin MG, Hendrickson BA, Johansen FE, Svärd SG, Gillin FD, Eckmann L. Polymeric Immunoglobulin Receptor in Intestinal Immune Defense against the Lumen-Dwelling Protozoan ParasiteGiardia. THE JOURNAL OF IMMUNOLOGY 2006; 177:6281-90. [PMID: 17056558 DOI: 10.4049/jimmunol.177.9.6281] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The polymeric Ig receptor (pIgR) is conserved in mammals and has an avian homologue, suggesting evolutionarily important functions in vertebrates. It transports multimeric IgA and IgM across polarized epithelia and is highly expressed in the intestine, yet little direct evidence exists for its importance in defense against common enteric pathogens. In this study, we demonstrate that pIgR can play a critical role in intestinal defense against the lumen-dwelling protozoan parasite Giardia, a leading cause of diarrheal disease. The receptor was essential for the eradication of Giardia when high luminal IgA levels were required. Clearance of Giardia muris, in which IgA plays a dominant role, was severely compromised in pIgR-deficient mice despite significant fecal IgA output at 10% of normal levels. In contrast, eradication of the human strain Giardia lamblia GS/M, for which adaptive immunity is less IgA dependent in mice, was unaffected by pIgR deficiency, indicating that pIgR had no physiologic role when lower luminal IgA levels were sufficient for parasite elimination. Immune IgA was greatly increased in the serum of pIgR-deficient mice, conferred passive protection against Giardia, and recognized several conserved giardial Ags, including ornithine carbamoyltransferase, arginine deiminase, alpha-enolase, and alpha- and beta-giardins, that are also detected in human giardiasis. Corroborative observations were made in mice lacking the J chain, which is required for pIgR-dependent transepithelial IgA transport. These results, together with prior data on pIgR-mediated immune neutralization of luminal cholera toxin, suggest that pIgR is essential in intestinal defense against pathogenic microbes with high-level and persistent luminal presence.
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Affiliation(s)
- Barbara J Davids
- Department of Pathology, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92103, USA
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35
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Shirai H, Mokrab Y, Mizuguchi K. The guanidino-group modifying enzymes: structural basis for their diversity and commonality. Proteins 2006; 64:1010-23. [PMID: 16779844 DOI: 10.1002/prot.20863] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The guanidino-group modifying enzyme (GME) superfamily contains many drug targets, including metabolic enzymes from pathogenic microorganisms as well as key regulatory proteins from higher eukaryotes. These enzymes, despite their diverse sequences, adopt the common alpha/beta propeller fold and catalyze the modification of (methylated) guanidino groups. Our structural superposition and structure-based alignment for the GMEs have identified key residues that are involved in the catalysis and substrate binding. We have shown that conserved guanidino-carboxyl interactions are utilized in two different ways; the acidic residues in the catalytic site form hydrogen bonds to the substrate guanidino group, and the enzyme Arg residues at several key positions recognize the carboxyl group of the substrate and fix its orientation. Based on this observation, we have proposed rules for classifying the GME sequences and predicting their molecular function from the conservation of the key acidic and Arg residues. Other novel motifs have been identified, which involve residues that are not in direct contact with the substrate but are likely to stabilize the active-site conformation through hydrogen-bonding networks. In addition, we have examined the domain architecture of the GMEs. Although most members consist of a single catalytic domain, fold recognition analysis has identified a likely bifunctional enzyme from a cyanobacterium. It has also revealed common immunoglobulin-like beta-sandwich domains found in the enzymes that recognize protein substrates. These findings will be useful for predicting the precise mechanism of action for potential novel targets and designing therapeutic compounds against them.
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Affiliation(s)
- Hiroki Shirai
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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36
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Lu X, Li L, Feng X, Wu Y, Dunaway-Mariano D, Engen JR, Mariano PS. L-canavanine is a time-controlled mechanism-based inhibitor of Pseudomonas aeruginosa arginine deiminase. J Am Chem Soc 2006; 127:16412-3. [PMID: 16305225 DOI: 10.1021/ja056226p] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mechanism for inhibition of the Pseudomonas aeruginosa arginine deiminase (PaADI) by the arginine analogue l-canavanine was investigated. Inhibition by this substance (kinact = 0.31 +/- 0.03 min-1 and Ki = 1.7 +/- 0.5 mM) is associated with the formation of a modestly stable S-alkylthiouronium intermediate, detected by using kinetic techniques and identified by using electrospray ionization mass spectrometry. The electronic and/or orientation effects, caused by oxygen-for-methylene substitution in l-canavanine, on the rate of enzyme regeneration from the S-alkylthiouronium intermediate could serve as the basis for a strategy for the rational design of new slow substrate inhibitors of ADI.
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Affiliation(s)
- Xuefeng Lu
- Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131, USA
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37
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Lu X, Li L, Wu R, Feng X, Li Z, Yang H, Wang C, Guo H, Galkin A, Herzberg O, Mariano PS, Martin BM, Dunaway-Mariano D. Kinetic Analysis of Pseudomonas aeruginosa Arginine Deiminase Mutants and Alternate Substrates Provides Insight into Structural Determinants of Function. Biochemistry 2006; 45:1162-72. [PMID: 16430212 DOI: 10.1021/bi051591e] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
L-Arginine deiminase from Pseudomonas aeruginosa (PaADI) catalyzes the hydrolysis of arginine to citrulline and ammonia. PaADI belongs to the guanidino group-modifying enzyme superfamily (GMSF), which conserves backbone fold and a Cys-, His-, and Asp-based catalytic core. In this paper the contributions made by the PaADI core residues Cys406, His278, and Asp166 and the contribution from the neighboring Asp280 (conserved in most but not all GMSF members) to catalysis of the formation and hydrolysis of the Cys406-alkyluronium intermediate were accessed by kinetic analysis of site-directed mutants. In addition, solution hydrolysis in a chemical model of the S-alkylthiouronium intermediate was examined to reveal the importance of general base catalysis in the enzymatic reaction. Substitutions of the active site gating residue Arg401, the l-arginine C(alpha)NH(3)(+)(COO(-)) binding residues, Arg185, Arg243, and Asn160, or the His278 hydrogen bond partner, Glu224, were found to cause dramatic reductions in the enzyme turnover rate. These results are interpreted to suggest that electrostatic interactions play a dominant role in PaADI catalysis. Structural variations observed in P. aeruginosa GMSF enzymes PaADI, agmatine deiminase (PaAgDI), and N(omega),N(omega)-dimethylarginine dimethylaminohydrolase (PaDDAH) indicate an early divergence of the encoding genes. Arginine analogues that are known substrates for PaAgDI and PaDDAH were tested with PaADI to define clear boundaries of biochemical function in the three hydrolases. The conservation of a catalytic core associated with the common chemical function and the divergence of substrate-binding residues (as well as one key catalytic residue) to expand the substrate range provide insight into the evolution of the catalysts that form the GMSF.
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Affiliation(s)
- Xuefeng Lu
- Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131, USA
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Galkin A, Lu X, Dunaway-Mariano D, Herzberg O. Crystal structures representing the Michaelis complex and the thiouronium reaction intermediate of Pseudomonas aeruginosa arginine deiminase. J Biol Chem 2005; 280:34080-7. [PMID: 16091358 DOI: 10.1074/jbc.m505471200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
L-arginine deiminase (ADI) catalyzes the irreversible hydrolysis of L-arginine to citrulline and ammonia. In a previous report of the structure of apoADI from Pseudomonas aeruginosa, the four residues that form the catalytic motif were identified as Cys406, His278, Asp280, and Asp166. The function of Cys406 in nucleophilic catalysis has been demonstrated by transient kinetic studies. In this study, the structure of the C406A mutant in complex with L-arginine is reported to provide a snapshot of the enzyme.substrate complex. Through the comparison of the structures of apoenzyme and substrate-bound enzyme, a substrate-induced conformational transition, which might play an important role in activity regulation, was discovered. Furthermore, the position of the guanidinium group of the bound substrate relative to the side chains of His278, Asp280, and Asp166 indicated that these residues mediate multiple proton transfers. His278 and Asp280, which are positioned to activate the water nucleophile in the hydrolysis of the S-alkylthiouronium intermediate, were replaced with alanine to stabilize the intermediate for structure determination. The structures determined for the H278A and D280A mutants co-crystallized with L-arginine provide a snapshot of the S-alkylthiouronium adduct formed by attack of Cys406 on the guanidinium carbon of L-arginine followed by the elimination of ammonia. Asp280 and Asp166 engage in ionic interactions with the guanidinium group in the C406A ADI. L-arginine structure and might orient the reaction center and participate in proton transfer. Structure determination of D166A revealed the apoD166A ADI. The collection of structures is interpreted in the context of recent biochemical data to propose a model for ADI substrate recognition and catalysis.
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Affiliation(s)
- Andrey Galkin
- Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland 20850, USA
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Kim KT, Mok MTS, Edwards MR. Protein kinase B from Giardia intestinalis. Biochem Biophys Res Commun 2005; 334:333-41. [PMID: 16018966 DOI: 10.1016/j.bbrc.2005.06.106] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2005] [Accepted: 06/20/2005] [Indexed: 11/26/2022]
Abstract
A novel serine/threonine protein kinase from Giardia intestinalis (GiPKB) was isolated by a combination of PCR techniques. Analysis of the GiPKB sequence indicated that the encoded protein appears to be a member of a novel subgroup of serine/threonine protein kinases known as protein kinase B. Reverse transcription PCR and Northern hybridization showed that the transcription of GiPKB is developmentally regulated. The GiPKB was expressed as a recombinant protein, which was characterized and shown to have a protein kinase activity. The preferred substrate for the GiPKB was histone H1, while histone H2A, GSK3 peptide, GS peptide, and Kemptide were phosphorylated at about 96, 73, 51, and 40% of the activity with histone H1, respectively. Neither cAMP, Ca(2+), nor Ca(2+)/calmodulin stimulated the enzyme activity. The GiPKB utilized ATP rather than GTP as a phosphate donor with an apparent K(m) of 20 microM. The identification and characterization of this differentially and constitutively expressed GiPKB should allow further analysis of the regulation and signal transduction pathways in Giardia.
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Affiliation(s)
- Kyu-Tae Kim
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney 2052, Australia.
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40
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Griswold A, Chen YYM, Snyder JA, Burne RA. Characterization of the arginine deiminase operon of Streptococcus rattus FA-1. Appl Environ Microbiol 2004; 70:1321-7. [PMID: 15006749 PMCID: PMC368411 DOI: 10.1128/aem.70.3.1321-1327.2004] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The arginine deiminase system (ADS) is of critical importance in oral biofilm pH homeostasis and microbial ecology. The ADS consists of three enzymes. Arginine is hydrolyzed by AD (ArcA) to generate citrulline and ammonia. Citrulline is then converted to ornithine and carbamoylphosphate via ornithine carbamoyltransferase (ArcB). Finally, carbamate kinase (ArcC) transfers a phosphate from carbamoylphosphate to ADP, yielding ATP. Ammonia production from this pathway protects bacteria from lethal acidification, and ATP production provides a source of energy for the cells. The purpose of this study was to initiate a characterization of the arc operon of Streptococcus rattus, the least cariogenic and sole ADS-positive member of the mutans streptococci. Using an arcB gene fragment obtained by degenerate PCRs, the FA-1 arc operon was identified in subgenomic DNA libraries and sequence analysis was performed. Results showed that the genes encoding the AD pathway in S. rattus FA-1 are organized as an arcABCDT-adiR operon gene cluster, including the enzymes of the pathway, an arginine-ornithine antiporter (ArcD) and a putative regulatory protein (AdiR). The arcA transcriptional start site was identified by primer extension, and a sigma(70)-like promoter was mapped 5' to arcA. Reverse transcriptase PCR was used to establish that arcABCDT could be cotranscribed. Reporter gene fusions and AD assays demonstrated that the operon is regulated by substrate induction and catabolite repression, the latter apparently through a CcpA-dependent pathway.
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Affiliation(s)
- Ann Griswold
- Department of Oral Biology, University of Florida, Gainesville, Florida 32610, USA
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41
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Lu X, Galkin A, Herzberg O, Dunaway-Mariano D. Arginine Deiminase Uses an Active-Site Cysteine in Nucleophilic Catalysis ofl-Arginine Hydrolysis. J Am Chem Soc 2004; 126:5374-5. [PMID: 15113205 DOI: 10.1021/ja049543p] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Arginine deiminase (EC 3.5.3.6) catalyzes the hydrolysis of l-arginine to citrulline and ammonium ion, which is the first step of the microbial l-arginine degradation pathway. The deiminase conserves the active-site Cys-His-Asp motif found in several related enzymes that catalyze group-transfer reactions from the guanidinium center of arginine-containing substrates. For each of these enzymes, nucleophilic catalysis by the conserved Cys has been postulated but never tested. In this communication we report the results from rapid quench studies of single-turnover reactions carried out with recombinant Pseudomonas aeruginosa arginine deiminase and limiting [14C-1]l-arginine. The citrulline-formation and arginine-decay curves measured at 25 degrees C were fitted to yield apparent rate constants k = 3.6 +/- 0.1 s-1 and k = 4.2 +/- 0.1 s-1, respectively. The time course for the formation (k =13 s-1) and decay (k = 6.5 s-1) of 14C-labeled enzyme defined a kinetically competent intermediate. Under the same reaction conditions, the Cys406Ser mutant failed to form the 14C-labeled enzyme intermediate. These results, along with the recently reported enzyme X-ray structure (Galkin, A.; Kulakova, L.; Sarikaya, E.; Lim, K.; Howard, A.; Herzberg, O. J. Biol. Chem. 2004, 279, 14001-14008, evidence a reaction pathway in which l-arginine deimination proceeds via a covalent enzyme intermediate formed by ammonia displacement from the arginine guanidinum carbon by the active-site Cys406.
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Affiliation(s)
- Xuefeng Lu
- Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131, USA
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42
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Galkin A, Kulakova L, Sarikaya E, Lim K, Howard A, Herzberg O. Structural Insight into Arginine Degradation by Arginine Deiminase, an Antibacterial and Parasite Drug Target. J Biol Chem 2004; 279:14001-8. [PMID: 14701825 DOI: 10.1074/jbc.m313410200] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
l-Arginine deiminase (ADI) catalyzes the irreversible hydrolysis of arginine to citrulline and ammonia. ADI is involved in the first step of the most widespread anaerobic route of arginine degradation. ADI, missing in high eukaryotes, is a potential antimicrobial and antiparasitic drug target. We have determined the crystal structure of ADI from Pseudomonas aeruginosa by the multi-wavelength anomalous diffraction method at 2.45 A resolution. The structure exhibits similarity to other arginine-modifying or substituted arginine-modifying enzymes such as dimethylarginine dimethylaminohydrolase (DDAH), arginine:glycine amidinotransferase, and arginine:inosamine-phosphate amidinotransferase, despite the lack of significant amino acid sequence homology to these enzymes. The similarity spans a core domain comprising five betabetaalphabeta motifs arranged in a circle around a 5-fold pseudosymmetry axis. ADI contains an additional alpha-helical domain of novel topology inserted between the first and the second betabetaalphabeta modules. A catalytic triad, Cys-His-Glu/Asp (arranged in a different manner from that of the thiol proteases), seen in the other arginine-modifying enzymes is also conserved in ADI, as well as many other residues involved in substrate binding. Based on this conservation pattern and the assumption that the substrate binding mode is similar to that of DDAH, an ADI catalytic mechanism is proposed. The main players are Cys-406, which mounts the nucleophilic attack on the carbon atom of the guanidinium group of arginine, and His-278, which serves as a general base.
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Affiliation(s)
- Andrey Galkin
- Center for Advanced Research In Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland 20850, USA
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Barcelona-Andrés B, Marina A, Rubio V. Gene structure, organization, expression, and potential regulatory mechanisms of arginine catabolism in Enterococcus faecalis. J Bacteriol 2002; 184:6289-300. [PMID: 12399499 PMCID: PMC151947 DOI: 10.1128/jb.184.22.6289-6300.2002] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2002] [Accepted: 08/19/2002] [Indexed: 11/20/2022] Open
Abstract
Although Enteroccus faecalis is the paradigm for biochemical studies on the arginine deiminase (ADI) pathway of fermentative arginine catabolism, little genetic information exists on this pathway in this organism. We fill this important gap by characterizing, in an 8,228-bp region cloned from a lambdagt11 genomic library of E. faecalis, a five-gene cluster forming a transcriptional unit (revealed by Northern blots and primer extension in E. faecalis) that corresponds to the ADI operon. Four additional genes in the opposite DNA strand and one in the same DNA strand are also identified. Studies on the protein products, including heterologous expression and/or sequence comparisons, allow us to ascertain or propose functions for all but 1 of the 10 genes. The ADI operon genes, arcABCRD, encode, respectively, ADI, ornithine transcarbamylase, carbamate kinase, a putative Crp/Fnr-type regulator (ArcR), and a putative ornithine-arginine antiporter (ArcD). Arginine induces the expression of arcABCRD, most likely by means of two homologous ArgR/AhrC-type regulators encoded by two genes, argR1 and argR2, that precede arcABCRD in each DNA strand and that are transcribed monocistronically, their transcription being influenced differentially by glucose and arginine. Potential ArgR1/ArgR2 (double and single) binding sequences are found in the promoter regions of arcA and of argR1/argR2 themselves. In addition, putative binding sequences for ArcR and for CcpA are found, respectively, in the argR1/argR2 and arcA promoter regions. Of the three other genes identified, two form a transcriptional unit and encode a putative metal-sensitive transcriptional regulator (ArsR) and a cysteine protease.
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Affiliation(s)
- Belén Barcelona-Andrés
- Instituto de Biomedicina de Valencia (IBV-CSIC) Instituto de Investigaciones Citológicas (FVIB), Spain
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Holtsberg FW, Ensor CM, Steiner MR, Bomalaski JS, Clark MA. Poly(ethylene glycol) (PEG) conjugated arginine deiminase: effects of PEG formulations on its pharmacological properties. J Control Release 2002; 80:259-71. [PMID: 11943403 DOI: 10.1016/s0168-3659(02)00042-1] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Some tumors, such as melanomas and hepatocellular carcinomas, have a unique nutritional requirement for arginine. Thus, enzymatic degradation of extracellular arginine is one possible means for inhibiting these tumors. Arginine deiminase is an arginine degrading enzyme (ADI) that has been studied as an anti-cancer enzyme. However, ADI has a short serum half-life and, as a microbial enzyme, is highly immunogenic. Formulation of other therapeutic proteins with poly(ethylene glycol) (PEG) has overcome these problems. Here, ADI-PEGs were synthesized using PEGs of varying size, structure (linear or branched chain) and linker chemistries. All ADI-PEGs retained approximately 50% of enzyme activity when PEG was covalently attached to approximately 40% of the primary amines irrespective of the PEG molecular weight or attachment chemistry used. However, it was observed that, as the PEG size increases to 20 kDa, there was a corresponding increase in the pharmacokinetic (pK) and pharmacodynamic (pD) properties of the formulation. Variation in PEG linker or structure, or the use of PEGs >20,000 mw, did not affect the pK or pD. As has been shown with other therapeutic proteins, repeated injection of ADI-PEG into experimental animals resulted in significantly lower titers of antibodies against this protein than unmodified ADI. These data suggest that formulation of ADI with PEG of 20,000 mw results is the optimal method for formulating this promising therapeutic agent.
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Affiliation(s)
- Frederick W Holtsberg
- Department of Biology, T.H. Morgan Building, University of Kentucky, Lexington, KY 40506, USA
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Nixon JEJ, Wang A, Field J, Morrison HG, McArthur AG, Sogin ML, Loftus BJ, Samuelson J. Evidence for lateral transfer of genes encoding ferredoxins, nitroreductases, NADH oxidase, and alcohol dehydrogenase 3 from anaerobic prokaryotes to Giardia lamblia and Entamoeba histolytica. EUKARYOTIC CELL 2002; 1:181-90. [PMID: 12455953 PMCID: PMC118039 DOI: 10.1128/ec.1.2.181-190.2002] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Giardia lamblia and Entamoeba histolytica are amitochondriate, microaerophilic protists which use fermentation enzymes like those of bacteria to survive anaerobic conditions within the intestinal lumen. Genes encoding fermentation enzymes and related electron transport peptides (e.g., ferredoxins) in giardia organisms and amebae are hypothesized to be derived from either an ancient anaerobic eukaryote (amitochondriate fossil hypothesis), a mitochondrial endosymbiont (hydrogen hypothesis), or anaerobic bacteria (lateral transfer hypothesis). The goals here were to complete the molecular characterization of giardial and amebic fermentation enzymes and to determine the origins of the genes encoding them, when possible. A putative giardia [2Fe-2S]ferredoxin which had a hypothetical organelle-targeting sequence at its N terminus showed similarity to mitochondrial ferredoxins and the hydrogenosomal ferredoxin of Trichomonas vaginalis (another luminal protist). However, phylogenetic trees were star shaped, with weak bootstrap support, so we were unable to confirm or rule out the endosymbiotic origin of the giardia [2Fe-2S]ferredoxin gene. Putative giardial and amebic 6-kDa ferredoxins, ferredoxin-nitroreductase fusion proteins, and oxygen-insensitive nitroreductases each tentatively supported the lateral transfer hypothesis. Although there were not enough sequences to perform meaningful phylogenetic analyses, the unique common occurrence of these peptides and enzymes in giardia organisms, amebae, and the few anaerobic prokaryotes suggests the possibility of lateral transfer. In contrast, there was more robust phylogenetic evidence for the lateral transfer of G. lamblia genes encoding an NADH oxidase from a gram-positive coccus and a microbial group 3 alcohol dehydrogenase from thermoanaerobic prokaryotes. In further support of lateral transfer, the G. lamblia NADH oxidase and adh3 genes appeared to have an evolutionary history distinct from those of E. histolytica.
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Affiliation(s)
- Julie E J Nixon
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts 02115, USA
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Shirai H, Blundell TL, Mizuguchi K. A novel superfamily of enzymes that catalyze the modification of guanidino groups. Trends Biochem Sci 2001; 26:465-8. [PMID: 11504612 DOI: 10.1016/s0968-0004(01)01906-5] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Three enzymes, peptidyl-arginine deiminase from Porphyromonas gingivalis, arginine deiminase and amidinotransferase are traditionally classified separately. By combining PSI-BLAST and FUGUE, data presented in this article describe how these enzymes belong to a novel superfamily, adopting a common fold and sharing similar catalytic mechanisms.
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Affiliation(s)
- H Shirai
- Dept of Biochemistry, University of Cambridge, Old Addenbrookes Site, 80 Tennis Court Road, CB2 1GA, Cambridge, UK
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McArthur AG, Knodler LA, Silberman JD, Davids BJ, Gillin FD, Sogin ML. The evolutionary origins of eukaryotic protein disulfide isomerase domains: new evidence from the Amitochondriate protist Giardia lamblia. Mol Biol Evol 2001; 18:1455-63. [PMID: 11470836 DOI: 10.1093/oxfordjournals.molbev.a003931] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A phylogenetic analysis of protein disulfide isomerase (PDI) domain evolution was performed with the inclusion of recently reported PDIs from the amitochondriate protist Giardia lamblia, yeast PDIs that contain a single thioredoxin-like domain, and PDIs from a diverse selection of protists. We additionally report and include two new giardial PDIs, each with a single thioredoxin-like domain. Inclusion of protist PDIs in our analyses revealed that the evolutionary history of the endoplasmic reticulum may not be simple. Phylogenetic analyses support common ancestry of all eukaryotic PDIs from a thioredoxin ancestor and independent duplications of thioredoxin-like domains within PDIs throughout eukaryote evolution. This was particularly evident for Acanthamoeba PDI, Dictyostelium PDI, and mammalian erp5 domains. In contrast, gene duplication, instead of domain duplication, produces PDI diversity in G. lamblia. Based on our results and the known diversity of PDIs, we present a new hypothesis that the five single-domain PDIs of G. lamblia may reflect an ancestral mechanism of protein folding in the eukaryotic endoplasmic reticulum. The PDI complement of G. lamblia and yeast suggests that a combination of PDIs may be used as a redox chain analogous to that known for bacterial Dsb proteins.
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Affiliation(s)
- A G McArthur
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, Massachusetts 02543-1015, USA
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Abstract
Giardia lamblia is a common cause of diarrhea in humans and other mammals throughout the world. It can be distinguished from other Giardia species by light or electron microscopy. The two major genotypes of G. lamblia that infect humans are so different genetically and biologically that they may warrant separate species or subspecies designations. Trophozoites have nuclei and a well-developed cytoskeleton but lack mitochondria, peroxisomes, and the components of oxidative phosphorylation. They have an endomembrane system with at least some characteristics of the Golgi complex and encoplasmic reticulum, which becomes more extensive in encysting organisms. The primitive nature of the organelles and metabolism, as well as small-subunit rRNA phylogeny, has led to the proposal that Giardia spp. are among the most primitive eukaryotes. G. lamblia probably has a ploidy of 4 and a genome size of approximately 10 to 12 Mb divided among five chromosomes. Most genes have short 5' and 3' untranslated regions and promoter regions that are near the initiation codon. Trophozoites exhibit antigenic variation of an extensive repertoire of cysteine-rich variant-specific surface proteins. Expression is allele specific, and changes in expression from one vsp gene to another have not been associated with sequence alterations or gene rearrangements. The Giardia genome project promises to greatly increase our understanding of this interesting and enigmatic organism.
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Affiliation(s)
- R D Adam
- Department of Medicine, University of Arizona College of Medicine, 1501N. Campbell, Tucson, AZ 85724-5049, USA.
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Abstract
The anaerobic protozoa Giardia duodenalis, Trichomonas vaginalis, and Entamoeba histolytica infect up to a billion people each year. G. duodenalis and E. histolytica are primarily pathogens of the intestinal tract, although E. histolytica can form abscesses and invade other organs, where it can be fatal if left untreated. T. vaginalis infection is a sexually transmitted infection causing vaginitis and acute inflammatory disease of the genital mucosa. T. vaginalis has also been reported in the urinary tract, fallopian tubes, and pelvis and can cause pneumonia, bronchitis, and oral lesions. Respiratory infections can be acquired perinatally. T. vaginalis infections have been associated with preterm delivery, low birth weight, and increased mortality as well as predisposing to human immunodeficiency virus infection, AIDS, and cervical cancer. All three organisms lack mitochondria and are susceptible to the nitroimidazole metronidazole because of similar low-redox-potential anaerobic metabolic pathways. Resistance to metronidazole and other drugs has been observed clinically and in the laboratory. Laboratory studies have identified the enzyme that activates metronidazole, pyruvate:ferredoxin oxidoreductase, to its nitroso form and distinct mechanisms of decreasing drug susceptibility that are induced in each organism. Although the nitroimidazoles have been the drug family of choice for treating the anaerobic protozoa, G. duodenalis is less susceptible to other antiparasitic drugs, such as furazolidone, albendazole, and quinacrine. Resistance has been demonstrated for each agent, and the mechanism of resistance has been investigated. Metronidazole resistance in T. vaginalis is well documented, and the principal mechanisms have been defined. Bypass metabolism, such as alternative oxidoreductases, have been discovered in both organisms. Aerobic versus anaerobic resistance in T. vaginalis is discussed. Mechanisms of metronidazole resistance in E. histolytica have recently been investigated using laboratory-induced resistant isolates. Instead of downregulation of the pyruvate:ferredoxin oxidoreductase and ferredoxin pathway as seen in G. duodenalis and T. vaginalis, E. histolytica induces oxidative stress mechanisms, including superoxide dismutase and peroxiredoxin. The review examines the value of investigating both clinical and laboratory-induced syngeneic drug-resistant isolates and dissection of the complementary data obtained. Comparison of resistance mechanisms in anaerobic bacteria and the parasitic protozoa is discussed as well as the value of studies of the epidemiology of resistance.
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Affiliation(s)
- P Upcroft
- Queensland Institute of Medical Research and The Tropical Health Program, Australian Centre for International and Tropical Health and Nutrition, The University of Queensland, The Bancroft Centre, Brisbane, Queensland 4029, Australia.
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Knipp M, Vasák M. A colorimetric 96-well microtiter plate assay for the determination of enzymatically formed citrulline. Anal Biochem 2000; 286:257-64. [PMID: 11067748 DOI: 10.1006/abio.2000.4805] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
l-Citrulline constitutes a product of a number of enzymatic reactions. In the past a number of colorimetric methods for the determination of l-citrulline, upon its chemical modification with diacetyl monoxime at 95 degrees C, have been reported. However, all these methods are time- and material-consuming. In this work, using the same chemical reaction, a new method for the use in 96-well polystyrene microtiter plates was developed. The method is fast and requires substantially less material as the enzymatic reaction is performed in a volume of 60 microl. The applicability of this enzymatic assay was established using l-N(omega), N(omega)-dimethylarginine dimethylaminohydrolase, which generates l-citrulline from side-chain methylated derivatives of l-arginine. The detection limit for l-citrulline is about 0.2 nmol. In addition, our studies show that most commonly used biochemical buffers and buffer additives do not affect the assay. This method may prove useful in the studies of other l-citrulline producing enzymes including nitric oxide synthase.
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Affiliation(s)
- M Knipp
- Institute of Biochemistry, University of Zürich, Winterthurerstrasse 190, Zürich, CH-8057, Switzerland
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