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Jiang C, He BB, Zhao RL, Xu MJ, Houk KN, Zhao YL. Computational Exploration of How Enzyme XimE Converts Natural S-Epoxide to Pyran and R-Epoxide to Furan. ACS Catal 2021. [DOI: 10.1021/acscatal.1c01335] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Chuchu Jiang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People’s Republic of China
| | - Bei-Bei He
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People’s Republic of China
| | - Rosalinda L. Zhao
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Min-Juan Xu
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Centre for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
| | - K. N. Houk
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Yi-Lei Zhao
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People’s Republic of China
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2
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Xu G, Yang S. Diverse evolutionary origins of microbial [4 + 2]-cyclases in natural product biosynthesis. Int J Biol Macromol 2021; 182:154-161. [PMID: 33836196 DOI: 10.1016/j.ijbiomac.2021.04.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 04/01/2021] [Accepted: 04/02/2021] [Indexed: 10/21/2022]
Abstract
Natural [4 + 2]-cyclases catalyze concerted cycloaddition during biosynthesis of over 400 natural products reported. Microbial [4 + 2]-cyclases are structurally diverse with a broad range of substrates. Thus far, about 52 putative microbial [4 + 2]-cyclases of 13 different types have been characterized, with over 20 crystal structures. However, how these cyclases have evolved during natural product biosynthesis remains elusive. Structural and phylogenetic analyses suggest that these different types of [4 + 2]-cyclases might have diverse evolutionary origins, such as reductases, dehydratases, methyltransferases, oxidases, etc. Divergent evolution of enzyme function might have occurred in these different families. Understanding the independent evolutionary history of these cyclases would provide new insights into their catalysis mechanisms and the biocatalyst design.
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Affiliation(s)
- Gangming Xu
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
| | - Suiqun Yang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
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3
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Patterson SK, Singer RS. Development of a Polymerase Chain Reaction Assay for the Detection of Antibiotic Resistance Genes in Community DNA. J Vet Diagn Invest 2016; 18:172-81. [PMID: 16617698 DOI: 10.1177/104063870601800206] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Many methods are used to detect antibiotic resistance genes in samples. The objective of the study reported here was to compare polymerase chain reaction (PCR) analysis of community DNA with fecal culturing for detecting antibiotic resistance genes in cattle samples. In the laboratory-based portion of this study, known concentrations of an Escherichia coli strain with 3 antibiotic resistance genes ( cmy-2, flo, and cat) were added to feces from dairy cattle. These genes were used to assess the effect of various primer pairs, chromosomally versus plasmid-encoded genes, and gene copy number on the sensitivity of PCR amplification. Gene-specific PCR amplification was performed on the community DNA extracted from the feces. Feces were cultured for the inoculated strain. In the field-based portion of the study, 80 cattle fecal samples of unknown gene status were compared by use of similar methods. Culture and PCR amplification from community DNA extractions produced variable results, and this variability was most noticeable at dilutions that approached the detection limit of the assay. Typically, PCR amplification had a higher sensitivity than did culture for detecting the gene of interest. However, the sensitivity of culture was improved by plating on selective media containing antibiotics. The community DNA approach enables assessment of bacterial communities in complex samples such as feces, a task that can be prohibitive by budget or time constraints associated with culture methods. Through a strategic combination of culture and community DNA approaches, the relationship between specific selection pressures and the persistence and dissemination of specific resistance genes can be elucidated.
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Affiliation(s)
- Sheila K Patterson
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois, Urbana 61802, USA
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Rapa RA, Labbate M. The function of integron-associated gene cassettes in Vibrio species: the tip of the iceberg. Front Microbiol 2013; 4:385. [PMID: 24367362 PMCID: PMC3856429 DOI: 10.3389/fmicb.2013.00385] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 11/25/2013] [Indexed: 12/17/2022] Open
Abstract
The integron is a genetic element that incorporates mobile genes termed gene cassettes into a reserved genetic site via site-specific recombination. It is best known for its role in antibiotic resistance with one type of integron, the class 1 integron, a major player in the dissemination of antibiotic resistance genes across Gram negative pathogens and commensals. However, integrons are ancient structures with over 100 classes (including class 1) present in bacteria from the broader environment. While, the class 1 integron is only one example of an integron being mobilized into the clinical environment, it is by far the most successful. Unlike clinical class 1 integrons which are largely found on plasmids, other integron classes are found on the chromosomes of bacteria and carry diverse gene cassettes indicating a non-antibiotic resistance role(s). However, there is very limited knowledge on what these alternative roles are. This is particularly relevant to Vibrio species where gene cassettes make up approximately 1-3% of their entire genome. In this review, we discuss how emphasis on class 1 integron research has resulted in a limited understanding by the wider research community on the role of integrons in the broader environment. This has the capacity to be counterproductive in solving or improving the antibiotic resistance problem into the future. Furthermore, there is still a significant lack of knowledge on how gene cassettes in Vibrio species drive adaptation and evolution. From research in Vibrio rotiferianus DAT722, new insight into how gene cassettes affect cellular physiology offers new alternative roles for the gene cassette resource. At least a subset of gene cassettes are involved in host surface polysaccharide modification suggesting that gene cassettes may be important in processes such as bacteriophage resistance, adhesion/biofilm formation, protection from grazers and bacterial aggregation.
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Affiliation(s)
- Rita A Rapa
- ithree Institute, University of Technology Sydney, NSW, Australia ; Department of Medical and Molecular Biosciences, University of Technology Sydney, NSW, Australia
| | - Maurizio Labbate
- ithree Institute, University of Technology Sydney, NSW, Australia ; Department of Medical and Molecular Biosciences, University of Technology Sydney, NSW, Australia
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5
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Rapa RA, Shimmon R, Djordjevic SP, Stokes HW, Labbate M. Deletion of integron-associated gene cassettes impact on the surface properties of Vibrio rotiferianus DAT722. PLoS One 2013; 8:e58430. [PMID: 23484028 PMCID: PMC3590141 DOI: 10.1371/journal.pone.0058430] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 02/06/2013] [Indexed: 01/21/2023] Open
Abstract
Background The integron is a genetic recombination system that catalyses the acquisition of genes on mobilisable elements called gene cassettes. In Vibrio species, multiple acquired gene cassettes form a cassette array that can comprise 1–3% of the bacterial genome. Since 75% of these gene cassettes contain genes encoding proteins of uncharacterised function, how the integron has driven adaptation and evolution in Vibrio species remains largely unknown. A feature of cassette arrays is the presence of large indels. Using Vibrio rotiferianus DAT722 as a model organism, the aim of this study was to determine how large cassette deletions affect vibrio physiology with a view to improving understanding into how cassette arrays influence bacterial host adaptation and evolution. Methodology/Principal Findings Biological assays and proteomic techniques were utilised to determine how artificially engineered deletions in the cassette array of V. rotiferianus DAT722 affected cell physiology. Multiple phenotypes were identified including changes to growth and expression of outer membrane porins/proteins and metabolic proteins. Furthermore, the deletions altered cell surface polysaccharide with Proton Nuclear Magnetic Resonance on whole cell polysaccharide identifying changes in the carbohydrate ring proton region indicating that gene cassette products may decorate host cell polysaccharide via the addition or removal of functional groups. Conclusions/Significance From this study, it was concluded that deletion of gene cassettes had a subtle effect on bacterial metabolism but altered host surface polysaccharide. Deletion (and most likely rearrangement and acquisition) of gene cassettes may provide the bacterium with a mechanism to alter its surface properties, thus impacting on phenotypes such as biofilm formation. Biofilm formation was shown to be altered in one of the deletion mutants used in this study. Reworking surface properties may provide an advantage to the bacterium’s interactions with organisms such as bacteriophage, protozoan grazers or crustaceans.
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Affiliation(s)
- Rita A. Rapa
- The ithree Institute, University of Technology, Sydney, Australia
| | - Ronald Shimmon
- Chemical Technology and Forensic Science, University of Technology, Sydney, Australia
| | | | - H. W. Stokes
- The ithree Institute, University of Technology, Sydney, Australia
| | - Maurizio Labbate
- The ithree Institute, University of Technology, Sydney, Australia
- * E-mail:
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6
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Sureshan V, Deshpande CN, Boucher Y, Koenig JE, Midwest Center for Structural Genomics, Stokes HW, Harrop SJ, Curmi PMG, Mabbutt BC. Integron gene cassettes: a repository of novel protein folds with distinct interaction sites. PLoS One 2013; 8:e52934. [PMID: 23349695 PMCID: PMC3548836 DOI: 10.1371/journal.pone.0052934] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2012] [Accepted: 11/26/2012] [Indexed: 11/19/2022] Open
Abstract
Mobile gene cassettes captured within integron arrays encompass a vast and diverse pool of genetic novelty. In most cases, functional annotation of gene cassettes directly recovered by cassette-PCR is obscured by their characteristically high sequence novelty. This inhibits identification of those specific functions or biological features that might constitute preferential factors for lateral gene transfer via the integron system. A structural genomics approach incorporating x-ray crystallography has been utilised on a selection of cassettes to investigate evolutionary relationships hidden at the sequence level. Gene cassettes were accessed from marine sediments (pristine and contaminated sites), as well as a range of Vibrio spp. We present six crystal structures, a remarkably high proportion of our survey of soluble proteins, which were found to possess novel folds. These entirely new structures are diverse, encompassing all-α, α+β and α/β fold classes, and many contain clear binding pocket features for small molecule substrates. The new structures emphasise the large repertoire of protein families encoded within the integron cassette metagenome and which remain to be characterised. Oligomeric association is a notable recurring property common to these new integron-derived proteins. In some cases, the protein–protein contact sites utilised in homomeric assembly could instead form suitable contact points for heterogeneous regulator/activator proteins or domains. Such functional features are ideal for a flexible molecular componentry needed to ensure responsive and adaptive bacterial functions.
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Affiliation(s)
- Visaahini Sureshan
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Chandrika N. Deshpande
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Yan Boucher
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Jeremy E. Koenig
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | | | - H. W. Stokes
- ithree institute, University of Technology, Sydney, New South Wales, Australia
| | - Stephen J. Harrop
- School of Physics, University of New South Wales, New South Wales, Australia
| | - Paul M. G. Curmi
- School of Physics, University of New South Wales, New South Wales, Australia
- Centre for Applied Medical Research, St Vincent's Hospital, Sydney, New South Wales, Australia
| | - Bridget C. Mabbutt
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
- * E-mail:
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7
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Lashin SA, Matushkin YG, Suslov VV, Kolchanov NA. Computer modeling of genome complexity variation trends in prokaryotic communities under varying habitat conditions. Ecol Modell 2012. [DOI: 10.1016/j.ecolmodel.2011.11.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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8
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Affiliation(s)
- Guillaume Cambray,
- Institut Pasteur, Unité Plasticité du Génome Bactérien, Département Génomes et Génétique, F-75015 Paris, France;
- CNRS, URA2171, F-75015 Paris, France
| | - Anne-Marie Guerout,
- Institut Pasteur, Unité Plasticité du Génome Bactérien, Département Génomes et Génétique, F-75015 Paris, France;
- CNRS, URA2171, F-75015 Paris, France
| | - Didier Mazel
- Institut Pasteur, Unité Plasticité du Génome Bactérien, Département Génomes et Génétique, F-75015 Paris, France;
- CNRS, URA2171, F-75015 Paris, France
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9
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Abstract
Large population sizes, rapid growth and 3.8 billion years of evolution firmly establish microorganisms as a major source of the planet's biological and genetic diversity. However, up to 99% of the microorganisms in a given environment cannot be cultured. Culture-independent methods that directly access the genetic potential of an environmental sample can unveil new proteins with diverse functions, but the sequencing of random DNA can generate enormous amounts of extraneous data. Integrons are recombination systems that accumulate open reading frames (gene cassettes), many of which code for functional proteins with enormous adaptive potential. Some integrons harbor hundreds of gene cassettes and evidence suggests that the gene cassette pool may be limitless in size. Accessing this genetic pool has been hampered since sequence-based techniques, such as hybridization or PCR, often recover only partial genes or a small subset of those present in the sample. Here, a three-plasmid genetic strategy for the sequence-independent recovery of gene cassettes from genomic libraries is described and its use by retrieving functional gene cassettes from the chromosomal integron of Vibrio vulnificus ATCC 27562 is demonstrated. By manipulating the natural activity of integrons, we can gain access to the caches of functional genes amassed by these structures.
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Affiliation(s)
- Dean A Rowe-Magnus
- Division of Clinical Integrative Biology, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, S1-26A, Toronto, Ontario M4N 3N5, Canada.
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10
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Labbate M, Case RJ, Stokes HW. The integron/gene cassette system: an active player in bacterial adaptation. Methods Mol Biol 2009; 532:103-25. [PMID: 19271181 DOI: 10.1007/978-1-60327-853-9_6] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
The integron includes a site-specific recombination system capable of integrating and expressing genes contained in structures called mobile gene cassettes. Integrons were originally identified on mobile elements from pathogenic bacteria and were found to be a major reservoir of antibiotic-resistance genes. Integrons are now known to be ancient structures that are phylogenetically diverse and, to date, have been found in approximately 9% of sequenced bacterial genomes. Overall, gene diversity in cassettes is extraordinarily high, suggesting that the integron/gene cassette system has a broad role in adaptation rather than being confined to simply conferring resistance to antibiotics. In this chapter, we provide a review of the integron/gene cassette system highlighting characteristics associated with this system, diversity of elements contained within it, and their importance in driving bacterial evolution and consequently adaptation. Ideas on the evolution of gene cassettes and gene cassette arrays are discussed.
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Affiliation(s)
- Maurizio Labbate
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, Australia
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11
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Robinson A, Guilfoyle AP, Sureshan V, Howell M, Harrop SJ, Boucher Y, Stokes HW, Curmi PMG, Mabbutt BC. Structural genomics of the bacterial mobile metagenome: an overview. Methods Mol Biol 2008; 426:589-95. [PMID: 18542892 DOI: 10.1007/978-1-60327-058-8_39] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Mobile gene cassettes collectively carry a highly diverse pool of novel genes, ostensibly for purposes of microbial adaptation. At the sequence level, putative functions can only be assigned to a minority of carried ORFs due to their inherent novelty. Having established these mobilized genes code for folded and functional proteins, the authors have recently adopted the procedures of structural genomics to efficiently sample their structures, thereby scoping their functional range. This chapter outlines protocols used to produce cassette-associated genes as recombinant proteins in Escherichia coli and crystallization procedures based on the dual screen/pH optimization approach of the SECSG (SouthEast Collaboratory for Structural Genomics). Crystal structures solved to date have defined unique members of enzyme fold classes associated with transport and nucleotide metabolism.
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Affiliation(s)
- Andrew Robinson
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Australia
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12
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Beinker P, Lohkamp B, Peltonen T, Niemi J, Mäntsälä P, Schneider G. Crystal Structures of SnoaL2 and AclR: Two Putative Hydroxylases in the Biosynthesis of Aromatic Polyketide Antibiotics. J Mol Biol 2006; 359:728-40. [PMID: 16650858 DOI: 10.1016/j.jmb.2006.03.060] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Revised: 03/23/2006] [Accepted: 03/29/2006] [Indexed: 11/25/2022]
Abstract
SnoaL2 and AclR are homologous enzymes in the biosynthesis of the aromatic polyketides nogalamycin in Streptomyces nogalater and cinerubin in Streptomyces galilaeus, respectively. Evidence obtained from gene transfer experiments suggested that SnoaL2 catalyzes the hydroxylation of the C-1 carbon atom of the polyketide chain. Here we show that AclR is also involved in the production of 1-hydroxylated anthracyclines in vivo. The three-dimensional structure of SnoaL2 has been determined by multi-wavelength anomalous diffraction to 2.5A resolution, and that of AclR to 1.8A resolution using molecular replacement. Both enzymes are dimers in solution and in the crystal. The fold of the enzyme subunits consists of an alpha+beta barrel. The dimer interface is formed by packing of the beta-sheets from the two subunits against each other. In the interior of the alpha+beta barrel a hydrophobic cavity is formed that most likely binds the substrate and harbors the active site. The subunit fold and the architecture of the active site in SnoaL2 and AclR are similar to that of the polyketide cyclases SnoaL and AknH; however, they show completely different quaternary structures. A comparison of the active site pockets of the putative hydroxylases AclR and SnoaL2 with those of bona fide polyketide cyclases reveals distinct differences in amino acids lining the cavity that might be responsible for the switch in chemistry. The moderate degree of sequence similarity and the preservation of the three-dimensional fold of the polypeptide chain suggest that these enzymes are evolutionary related. Members of this enzyme family appear to have evolved from a common protein scaffold by divergent evolution to catalyze reactions chemically as diverse as aldol condensation and hydroxylation.
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Affiliation(s)
- Philipp Beinker
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm S-171 77, Sweden
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13
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Gallimore AR, Stark CBW, Bhatt A, Harvey BM, Demydchuk Y, Bolanos-Garcia V, Fowler DJ, Staunton J, Leadlay PF, Spencer JB. Evidence for the role of the monB genes in polyether ring formation during monensin biosynthesis. CHEMISTRY & BIOLOGY 2006; 13:453-60. [PMID: 16632258 DOI: 10.1016/j.chembiol.2006.01.013] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2005] [Revised: 12/23/2005] [Accepted: 01/18/2006] [Indexed: 10/24/2022]
Abstract
Ionophoric polyethers are produced by the exquisitely stereoselective oxidative cyclization of a linear polyketide, probably via a triepoxide intermediate. We report here that deletion of either or both of the monBI and monBII genes from the monensin biosynthetic gene cluster gave strains that produced, in place of monensins A and B, a mixture of C-3-demethylmonensins and a number of minor components, including C-9-epi-monensin A. All the minor components were efficiently converted into monensins by subsequent acid treatment. These data strongly suggest that epoxide ring opening and concomitant polyether ring formation are catalyzed by the MonB enzymes, rather than by the enzyme MonCII as previously thought. Consistent with this, homology modeling shows that the structure of MonB-type enzymes closely resembles the recently determined structure of limonene-1,2-epoxide hydrolase from Rhodococcus erythropolis.
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Affiliation(s)
- Andrew R Gallimore
- Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, United Kingdom
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14
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Liu JW, Boucher Y, Stokes HW, Ollis DL. Improving protein solubility: the use of the Escherichia coli dihydrofolate reductase gene as a fusion reporter. Protein Expr Purif 2005; 47:258-63. [PMID: 16403649 DOI: 10.1016/j.pep.2005.11.019] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Revised: 11/04/2005] [Accepted: 11/18/2005] [Indexed: 11/15/2022]
Abstract
We have devised a strategy for screening mutant libraries for enzyme variants with enhanced solubility. The method is based on the observation that Escherichia coli can become insensitive to the antibiotic trimethoprim (TMP) if dihydrofolate reductase (DHFR) is expressed at an appropriate level. DHFR is a very soluble protein and can be expressed at levels that exceed normally lethal concentrations of TMP. In our approach, the gene encoding an insoluble target protein is placed in a vector so that the translated protein will be fused to DHFR. The resulting fusion protein will form inclusion bodies and inactivate DHFR-the cells will be susceptible to TMP. Mutations to the target protein that make it more soluble will also make the fusion protein more soluble so that DHFR will be at least partially active-the cells will be resistant to TMP. As the solubility of the target protein increases, the cells will become more resistant to TMP. The system was tested with a putative acetyltransferase (ACE) from a strain of the marine bacterium Vibrio fischerii. The gene encoding this protein was of interest since it is part of a mobile gene cassette within an integron array of the strain in question. After multiple rounds of shuffling and selection, ACE mutants were produced that had significantly improved solubility.
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Affiliation(s)
- Jian-Wei Liu
- Research School of Chemistry, Building 35 Science Road, Australian National University, Canberra ACT 0200, Australia
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15
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Johansson P, Unge T, Cronin A, Arand M, Bergfors T, Jones TA, Mowbray SL. Structure of an Atypical Epoxide Hydrolase from Mycobacterium tuberculosis Gives Insights into its Function. J Mol Biol 2005; 351:1048-56. [PMID: 16051262 DOI: 10.1016/j.jmb.2005.06.055] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2005] [Revised: 06/17/2005] [Accepted: 06/21/2005] [Indexed: 10/25/2022]
Abstract
Epoxide hydrolases are vital to many organisms by virtue of their roles in detoxification, metabolism and processing of signaling molecules. The Mycobacterium tuberculosis genome encodes an unusually large number of epoxide hydrolases, suggesting that they might be of particular importance to these bacteria. We report here the first structure of an epoxide hydrolase from M.tuberculosis, solved to a resolution of 2.5 A using single-wavelength anomalous dispersion (SAD) from a selenomethionine-substituted protein. The enzyme features a deep active-site pocket created by the packing of three helices onto a curved six-stranded beta-sheet. This structure is similar to a previously described limonene-1,2-epoxide hydrolase from Rhodococcus erythropolis and unlike the alpha/beta-hydrolase fold typical of mammalian epoxide hydrolases (EH). A number of changes in the mycobacterial enzyme create a wider and deeper substrate-binding pocket than is found in its Rhodococcus homologue. Interestingly, each structure contains a different type of endogenous ligand of unknown origin bound in its active site. As a consequence of its wider substrate-binding pocket, the mycobacterial EH is capable of hydrolyzing long or bulky lipophilic epoxides such as 10,11-epoxystearic acid and cholesterol 5,6-oxide at appreciable rates, suggesting that similar compound(s) will serve as its physiological substrate(s).
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Affiliation(s)
- Patrik Johansson
- Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, Box 596, SE-751 24 Uppsala, Sweden
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