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Han KK, Zhou Q, Tian M, Li YN, Zhang JY, Zhang YW. Cloning, heterologous expression, and molecular characterization of a highly active and stable non-specific endonuclease from Pseudomonas fluorescens. Arch Microbiol 2024; 206:125. [PMID: 38411841 DOI: 10.1007/s00203-024-03867-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 01/23/2024] [Accepted: 01/24/2024] [Indexed: 02/28/2024]
Abstract
Non-specific endonucleases can be used for the digestion of nucleic acids because they hydrolyze DNA/RNA into 3-5 base pairs (bp) length oligonucleotide fragments without strict selectivity. In this work, a novel non-specific endonuclease from Pseudomonas fluorescens (PfNuc) with high activities for both DNA and RNA was successfully cloned and expressed in Escherichia coli. The production of PfNuc in flask scale could be achieved to 1.73 × 106 U/L and 4.82 × 106 U/L for DNA and RNA by investigation of the culture and induction conditions. The characterization of PfNuc indicated that it was Mg2+-dependent and the catalytic activity was enhanced by 3.74 folds for DNA and 1.06 folds for RNA in the presence of 5 mM Mg2+. The specific activity of PfNuc for DNA was 1.44 × 105 U/mg at pH 8.0 and 40 °C, and 3.93 × 105 U/mg for RNA at pH 8.5 and 45 °C. The Km of the enzyme for both DNA and RNA was close to 43 µM. The Vmax was 6.40 × 105 U/mg and 1.11 × 106 U/mg for DNA and RNA, respectively. There was no observed activity loss when PfNuc was stored at 4 °C and - 20 °C after 28 days or 10 repeated freeze-thaw cycles at - 80 °C. Molecular docking revealed that PfNuc formed 17 and 19 hydrogen bonds with single-stranded RNA and double-stranded DNA, respectively. These results could explain the high activity and stability of PfNuc, suggesting its great potential applications in the industry and clinic.
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Affiliation(s)
- Ke-Ke Han
- School of Pharmacy, Jiangsu University, Zhenjiang, 212013, People's Republic of China
| | - Qiang Zhou
- School of Pharmacy, Jiangsu University, Zhenjiang, 212013, People's Republic of China
| | - Miao Tian
- School of Pharmacy, Jiangsu University, Zhenjiang, 212013, People's Republic of China
| | - Yang-Nan Li
- School of Pharmacy, Jiangsu University, Zhenjiang, 212013, People's Republic of China
| | - Jing-Yi Zhang
- School of Pharmacy, Jiangsu University, Zhenjiang, 212013, People's Republic of China
| | - Ye-Wang Zhang
- School of Pharmacy, Jiangsu University, Zhenjiang, 212013, People's Republic of China.
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Riemerella anatipestifer AS87_RS02955 Acts as a Virulence Factor and Displays Endonuclease Activity. Appl Environ Microbiol 2022; 88:e0127622. [PMID: 36106871 PMCID: PMC9552600 DOI: 10.1128/aem.01276-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Riemerella anatipestifer is an important bacterial pathogen in the global duck industry and causes heavy economic losses. In our previous study, we demonstrated that R. anatipestifer type IX secretion system components GldK and GldM, and the secretion protein metallophosphoesterase, acted as virulence factors. In this study, R. anatipestifer AS87_RS02955 was investigated for virulence and enzymatic activity properties. We constructed AS87_RS02955 mutation and complementation strains to assess bacterial virulence. In vivo bacterial loads showed a significantly reduced bacterial loads in the blood of ducks infected with mutant strain Yb2Δ02955, which was recovered in the blood of ducks infected with the complementation strain cYb2Δ02955, demonstrating that AS87_RS02955 was associated with virulence. Further studies showed AS87_RS02955 was a novel nonspecific endonuclease with no functionally conserved domain, but enzymatic activity toward DNA and RNA was indicated. DNase activity was activated by Zn2+, Cu2+, Mg2+, Ca2+, and Mn2+ ions but inhibited by ethylenediaminetetraacetic acid. RNase activity was independent of metal cations, but stimulated by Mg2+, Ca2+, and Mn2+. RAS87_RS02955 enzymatic activity was active across a broad pH and temperature range. Moreover, we identified four sites in rAS87_RS02955, F39, F92, I134, and F145, which were critical for enzymatic activity. In summary, we showed that R. anatipestifer AS87_RS02955 encoded a novel endonuclease with important roles in bacterial virulence. IMPORTANCE R. anatipestifer AS87_RS02955 was identified as a novel T9SS effector and displayed a nonspecific endonuclease activity in this study. The protein did not contain a conserved His-Asn-His motif structure, which is similar to the endonuclease from Prevotella sp. Its mutant strain Yb2Δ02955 demonstrated significantly attenuated virulence, suggesting AS87_RS02955 is an important virulence factor. Moreover, AS87_RS02955 displayed nonspecific endonuclease activity to cleave λ DNA and MS2 RNA, while four protein sites were critical for endonuclease activity. In conclusion, R. anatipestifer AS87_RS02955 plays important roles in bacterial virulence.
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Sebesta J, Xiong W, Guarnieri MT, Yu J. Biocontainment of Genetically Engineered Algae. FRONTIERS IN PLANT SCIENCE 2022; 13:839446. [PMID: 35310623 PMCID: PMC8924478 DOI: 10.3389/fpls.2022.839446] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 02/07/2022] [Indexed: 06/14/2023]
Abstract
Algae (including eukaryotic microalgae and cyanobacteria) have been genetically engineered to convert light and carbon dioxide to many industrially and commercially relevant chemicals including biofuels, materials, and nutritional products. At industrial scale, genetically engineered algae may be cultivated outdoors in open ponds or in closed photobioreactors. In either case, industry would need to address a potential risk of the release of the engineered algae into the natural environment, resulting in potential negative impacts to the environment. Genetic biocontainment strategies are therefore under development to reduce the probability that these engineered bacteria can survive outside of the laboratory or industrial setting. These include active strategies that aim to kill the escaped cells by expression of toxic proteins, and passive strategies that use knockouts of native genes to reduce fitness outside of the controlled environment of labs and industrial cultivation systems. Several biocontainment strategies have demonstrated escape frequencies below detection limits. However, they have typically done so in carefully controlled experiments which may fail to capture mechanisms of escape that may arise in the more complex natural environment. The selection of biocontainment strategies that can effectively kill cells outside the lab, while maintaining maximum productivity inside the lab and without the need for relatively expensive chemicals will benefit from further attention.
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Kinetics of DNA looping by Anabaena sensory rhodopsin transducer (ASRT) by using DNA cyclization assay. Sci Rep 2021; 11:23721. [PMID: 34887464 PMCID: PMC8660804 DOI: 10.1038/s41598-021-03148-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 11/29/2021] [Indexed: 11/09/2022] Open
Abstract
DNA cyclization assay together with single-molecule FRET was employed to monitor protein-mediated bending of a short dsDNA (~ 100 bp). This method provides a simple and easy way to monitor the structural change of DNA in real-time without necessitating prior knowledge of the molecular structures for the optimal dye-labeling. This assay was applied to study how Anabaena sensory rhodopsin transducer (ASRT) facilitates loop formation of DNA as a possible mechanism for gene regulation. The ASRT-induced DNA looping was maximized at 50 mM of Na+, while Mg2+ also played an essential role in the loop formation.
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Schmitz S, Wieczorek M, Nölle V, Elleuche S. Characterization of Single Amino Acid Variations in an EDTA-Tolerating Non-specific Nuclease from the Ice-Nucleating Bacterium Pseudomonas syringae. Mol Biotechnol 2019; 62:67-78. [PMID: 31749083 DOI: 10.1007/s12033-019-00229-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Non-specific nuclease (NSN) can be applied in industrial downstream processing to remove nucleic acids from crude protein extracts or in cell-sorting systems to degrade nucleic acids derived from lysed cells. PsNuc from the ice-nucleating bacterium Pseudomonas syringae has the ability to decompose double- and single-stranded DNA in linear or circular form and RNA. It is not affected by the presence of metal-ion chelators such as EDTA and tolerates several protease inhibitors and reducing agents. A multiple sequence alignment of PsNuc with closely related enzymes (97-99% identity on the protein level) within the family Pseudomonaceae revealed the presence of only six amino acid residues that are variable in putative NSN from different members of the genus Pseudomonas. Single amino acid variants were produced in recombinant form in Escherichia coli, purified, and characterized. They showed similar activity compared to PsNuc, but a single variant even displayed an improved performance with an activity of > 20,000 U/mg at 35 °C, while amino acid residues S148 and V161 were found to be essential for enzymatic functionality. These results suggest that homologous nucleases from Pseudomonaceae display high activity levels in a metal-ion-independent manner and are therefore of interest for applications in biotechnology.
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Affiliation(s)
- Sarah Schmitz
- Miltenyi Biotec B.V. & Co. KG, Friedrich-Ebert-Straße 68, 51429, Bergisch Gladbach, Germany
| | - Marek Wieczorek
- Miltenyi Biotec B.V. & Co. KG, Friedrich-Ebert-Straße 68, 51429, Bergisch Gladbach, Germany
| | - Volker Nölle
- Miltenyi Biotec B.V. & Co. KG, Friedrich-Ebert-Straße 68, 51429, Bergisch Gladbach, Germany
| | - Skander Elleuche
- Miltenyi Biotec B.V. & Co. KG, Friedrich-Ebert-Straße 68, 51429, Bergisch Gladbach, Germany.
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Baslé A, Hewitt L, Koh A, Lamb HK, Thompson P, Burgess JG, Hall MJ, Hawkins AR, Murray H, Lewis RJ. Crystal structure of NucB, a biofilm-degrading endonuclease. Nucleic Acids Res 2018; 46:473-484. [PMID: 29165717 PMCID: PMC5758888 DOI: 10.1093/nar/gkx1170] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 11/13/2017] [Indexed: 01/23/2023] Open
Abstract
Bacterial biofilms are a complex architecture of cells that grow on moist interfaces, and are held together by a molecular glue of extracellular proteins, sugars and nucleic acids. Biofilms are particularly problematic in human healthcare as they can coat medical implants and are thus a potential source of disease. The enzymatic dispersal of biofilms is increasingly being developed as a new strategy to treat this problem. Here, we have characterized NucB, a biofilm-dispersing nuclease from a marine strain of Bacillus licheniformis, and present its crystal structure together with the biochemistry and a mutational analysis required to confirm its active site. Taken together, these data support the categorization of NucB into a unique subfamily of the ββα metal-dependent non-specific endonucleases. Understanding the structure and function of NucB will facilitate its future development into an anti-biofilm therapeutic agent.
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Affiliation(s)
- Arnaud Baslé
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Lorraine Hewitt
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Alan Koh
- Centre for Bacterial Cell Biology, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4AX, UK
| | - Heather K Lamb
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Paul Thompson
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - J Grant Burgess
- Marine Biology, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
| | - Michael J Hall
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
| | - Alastair R Hawkins
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Heath Murray
- Centre for Bacterial Cell Biology, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4AX, UK
| | - Richard J Lewis
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK,To whom correspondence should be addressed. Tel: +44 191 208 5482;
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Characterization of a DUF820 family protein Alr3200 of the cyanobacterium Anabaena sp. strain PCC7120. J Biosci 2016; 41:589-600. [DOI: 10.1007/s12038-016-9646-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Čelešnik H, Tanšek A, Tahirović A, Vižintin A, Mustar J, Vidmar V, Dolinar M. Biosafety of biotechnologically important microalgae: intrinsic suicide switch implementation in cyanobacterium Synechocystis sp. PCC 6803. Biol Open 2016; 5:519-28. [PMID: 27029902 PMCID: PMC4890671 DOI: 10.1242/bio.017129] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
In recent years, photosynthetic autotrophic cyanobacteria have attracted interest for biotechnological applications for sustainable production of valuable metabolites. Although biosafety issues can have a great impact on public acceptance of cyanobacterial biotechnology, biosafety of genetically modified cyanobacteria has remained largely unexplored. We set out to incorporate biocontainment systems in the model cyanobacterium Synechocystis sp. PCC 6803. Plasmid-encoded safeguards were constructed using the nonspecific nuclease NucA from Anabaena combined with different metal-ion inducible promoters. In this manner, conditional lethality was dependent on intracellular DNA degradation for regulated autokilling as well as preclusion of horizontal gene transfer. In cells carrying the suicide switch comprising the nucA gene fused to a variant of the copM promoter, efficient inducible autokilling was elicited. Parallel to nuclease-based safeguards, cyanobacterial toxin/antitoxin (TA) modules were examined in biosafety switches. Rewiring of Synechocystis TA pairs ssr1114/slr0664 and slr6101/slr6100 for conditional lethality using metal-ion responsive promoters resulted in reduced growth, rather than cell killing, suggesting cells could cope with elevated toxin levels. Overall, promoter properties and translation efficiency influenced the efficacy of biocontainment systems. Several metal-ion promoters were tested in the context of safeguards, and selected promoters, including a nrsB variant, were characterized by beta-galactosidase reporter assay. Summary: Biosafety of biotechnologically important microalgae was addressed by suicide switch implementation in cyanobacterium Synechocystis sp. PCC 6803. This is the first report of biocontainment safeguards in cyanobacteria.
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Affiliation(s)
- Helena Čelešnik
- Chair of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000, Slovenia
| | - Anja Tanšek
- Chair of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000, Slovenia
| | - Aneja Tahirović
- Chair of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000, Slovenia
| | - Angelika Vižintin
- Chair of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000, Slovenia
| | - Jernej Mustar
- Chair of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000, Slovenia
| | - Vita Vidmar
- Chair of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000, Slovenia
| | - Marko Dolinar
- Chair of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000, Slovenia
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Moon AF, Gaudu P, Pedersen LC. Structural characterization of the virulence factor nuclease A from Streptococcus agalactiae. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:2937-49. [PMID: 25372684 PMCID: PMC4220975 DOI: 10.1107/s1399004714019725] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 09/01/2014] [Indexed: 12/28/2022]
Abstract
The group B pathogen Streptococcus agalactiae commonly populates the human gut and urogenital tract, and is a major cause of infection-based mortality in neonatal infants and in elderly or immunocompromised adults. Nuclease A (GBS_NucA), a secreted DNA/RNA nuclease, serves as a virulence factor for S. agalactiae, facilitating bacterial evasion of the human innate immune response. GBS_NucA efficiently degrades the DNA matrix component of neutrophil extracellular traps (NETs), which attempt to kill and clear invading bacteria during the early stages of infection. In order to better understand the mechanisms of DNA substrate binding and catalysis of GBS_NucA, the high-resolution structure of a catalytically inactive mutant (H148G) was solved by X-ray crystallography. Several mutants on the surface of GBS_NucA which might influence DNA substrate binding and catalysis were generated and evaluated using an imidazole chemical rescue technique. While several of these mutants severely inhibited nuclease activity, two mutants (K146R and Q183A) exhibited significantly increased activity. These structural and biochemical studies have greatly increased our understanding of the mechanism of action of GBS_NucA in bacterial virulence and may serve as a foundation for the structure-based drug design of antibacterial compounds targeted to S. agalactiae.
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Affiliation(s)
- Andrea F. Moon
- Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Philippe Gaudu
- INRA, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France; AgroParisTech, UMR Micalis, Jouy-en-Josas, France
| | - Lars C. Pedersen
- Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
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Das A, Chakrabarti J, Ghosh M. Thermodynamics of interfacial changes in a protein–protein complex. ACTA ACUST UNITED AC 2014; 10:437-45. [DOI: 10.1039/c3mb70249a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Derré-Bobillot A, Cortes-Perez NG, Yamamoto Y, Kharrat P, Couvé E, Da Cunha V, Decker P, Boissier MC, Escartin F, Cesselin B, Langella P, Bermúdez-Humarán LG, Gaudu P. Nuclease A (Gbs0661), an extracellular nuclease of Streptococcus agalactiae, attacks the neutrophil extracellular traps and is needed for full virulence. Mol Microbiol 2013; 89:518-31. [PMID: 23772975 DOI: 10.1111/mmi.12295] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2013] [Indexed: 12/30/2022]
Abstract
Most bacteria of the genus Streptococcus are opportunistic pathogens, and some of them produce extracellular DNases, which may be important for virulence. Genome analyses of Streptococcus agalactiae (GBS) neonate isolate NEM316 revealed the presence of seven genes putatively encoding secreted DNases, although their functions, if any, are unknown. In this study, we observed that respiration growth of GBS led to the extracellular accumulation of a putative nuclease, identified as being encoded by the gbs0661 gene. When overproduced in Lactococcus lactis, the protein was found to be a divalent cation-requiring, pH-stable and heat-stable nuclease that we named Nuclease A (NucA). Substitution of the histidine(148) by alanine reduced nuclease activity of the GBS wild-type strain, indicating that NucA is the major nuclease ex vivo. We determined that GBS is able to degrade the DNA matrix comprising the neutrophil extracellular trap (NET). The nucA(H148A) mutant was impaired for this function, implicating NucA in the virulence of GBS. In vivo infection studies confirmed that NucA is required for full infection, as the mutant strain allowed increased bacterial clearance from lung tissue and decreased mortality in infected mice. These results show that NucA is involved in NET escape and is needed for full virulence.
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Zaw MT, Yamasaki E, Yamamoto S, Nair GB, Kawamoto K, Kurazono H. Uropathogenic specific protein gene, highly distributed in extraintestinal uropathogenic Escherichia coli, encodes a new member of H-N-H nuclease superfamily. Gut Pathog 2013; 5:13. [PMID: 23759109 PMCID: PMC3685522 DOI: 10.1186/1757-4749-5-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 06/05/2013] [Indexed: 01/12/2023] Open
Abstract
Background The uropathogenic specific protein (Usp) and three OrfU proteins (OrfU1, OrfU2 and OrfU3) are encoded in the putative small pathogenicity island which is closely associated with Uropathogenic Escherichia coli. Although homology search revealed that Usp and OrfUs have a homology with nuclease-type bacteriocins, which possess H-N-H nuclease motif, and immunity proteins respectively, the molecular activity of these proteins was never investigated. In this study, we try to over-express Usp in E. coli, purify Usp and characterize its molecular activity. Method Recombinant Usp protein was expressed in E. coli BL21(DE3) cells together with 6× Histidine tagged OrfU1 (OrfU1-His) protein, and purified with affinity chromatography using Ni2+ chelating agarose. The nuclease activity of the purified Usp was examined in vitro by using plasmid DNA as a substrate. The importance of H-N-H motif in nuclease activity of Usp was examined by site-directed mutagenesis study. Results We revealed that pET expression vector encoding Usp alone could not be maintained in E. coli BL21(DE3), and insertion of the orfUs as well as usp in the constructed plasmid diminished the toxic effect, suggesting that co-expressed OrfUs masked the activity of Usp. To purify Usp protein, we employed the expression vector encoding untagged Usp together with OrfU1-His. A tight complex formation could be observed between Usp and OrfU1-His, which allowed the purification of Usp in a single chromatographic step: binding of Usp/OrfU1-His complex to Ni2+ chelating agarose followed by elution of Usp from the complex with denaturing reagent. The purified free Usp was found to have the nuclease activity, and the activity was constitutively higher than Usp/OrfU1-His complex. H-N-H motif, which is found in various types of nucleases including a subfamily of nuclease-type bacteriocin, had been identified in the C-terminal region of Usp. Site-directed mutagenesis study showed that the H-N-H motif in Usp is indispensable for its nuclease activity. Conclusion This is the first evidence of the molecular activity of the new member of H-N-H superfamily and lays the foundation for the biological characterization of Usp and its inhibitor protein, OrfUs.
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Affiliation(s)
- Myo Thura Zaw
- Division of Food Hygiene, Department of Animal and Food Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan.
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Zhukhlistova NE, Balaev VV, Lyashenko AV, Lashkov AA. Structural aspects of catalytic mechanisms of endonucleases and their binding to nucleic acids. CRYSTALLOGR REP+ 2012. [DOI: 10.1134/s1063774512030236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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14
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Midon M, Gimadutdinow O, Meiss G, Friedhoff P, Pingoud A. Chemical Rescue of Active Site Mutants of S. pneumoniae Surface Endonuclease EndA and Other Nucleases of the HNH Family by Imidazole. Chembiochem 2012; 13:713-21. [DOI: 10.1002/cbic.201100775] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Indexed: 11/08/2022]
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15
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Padmaja N, Rajaram H, Apte SK. A novel hemerythrin DNase from the nitrogen-fixing cyanobacterium Anabaena sp. strain PCC7120. Arch Biochem Biophys 2010; 505:171-7. [PMID: 20946869 DOI: 10.1016/j.abb.2010.10.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 09/30/2010] [Accepted: 10/07/2010] [Indexed: 11/28/2022]
Abstract
The open reading frame alr3199 of the nitrogen-fixing cyanobacterium, Anabaena sp. strain PCC7120 was cloned and overexpressed in Escherichia coli. Purified recombinant Alr3199 protein was found to be a functionally active deoxyribonuclease with novel features, such as (1) no homology to typical DNases (2) a Ca²(+)-dependent Nickase activity (3) presence of a di-hemerythrin domain, and (4) requirement of Fe²(+) conjugated to hemerythrin domains for optimal activity. Both the DNase and Nickase activities were found to be associated with the N-terminal non-hemerythrin region, but were modulated by Fe²(+) conjugated to the C-terminal hemerythrin region. This is the first report of a hemerythrin protein with DNase activity, tentatively designated as 'HE-DNase', and with a possible role in stress-induced DNA damage/repair in Anabaena.
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Affiliation(s)
- N Padmaja
- Bhabha Atomic Research Centre, Trombay, Mumbai, India
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16
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Kieper J, Lauber C, Gimadutdinow O, Urbańska A, Cymerman I, Ghosh M, Szczesny B, Meiss G. Production and characterization of recombinant protein preparations of Endonuclease G-homologs from yeast, C. elegans and humans. Protein Expr Purif 2010; 73:99-106. [PMID: 20382228 DOI: 10.1016/j.pep.2010.04.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2010] [Revised: 04/05/2010] [Accepted: 04/06/2010] [Indexed: 11/25/2022]
Abstract
Nuc1p, CPS-6, EndoG and EXOG are evolutionary conserved mitochondrial nucleases from yeast, Caenorhabditis elegans and humans, respectively. These enzymes play an important role in programmed cell death as well as mitochondrial DNA-repair and recombination. Whereas a significant interest has been given to the cell biology of these proteins, in particular their recruitment during caspase-independent apoptosis, determination of their biochemical properties has lagged behind. In part, biochemical as well as structural analysis of mitochondrial nucleases has been hampered by the fact that upon cloning and overexpression in Escherichia coli these enzymes can exert considerable toxicity and tend to aggregate and form inclusion bodies. We have, therefore, established a uniform E. coli expression system allowing us to obtain these four evolutionary related nucleases in active form from the soluble as well as insoluble fractions of E. coli cell lysates. Using preparations of recombinant Nuc1p, CPS-6, EndoG and EXOG we have compared biochemical properties and the substrate specificities of these related nucleases on selected substrates in parallel. Whereas Nuc1p and EXOG in addition to their endonuclease activity exert 5'-3'-exonuclease activity, CPS-6 and EndoG predominantly are endonucleases. These findings allow speculating that the mechanisms of action of these related nucleases in cell death as well as DNA-repair and recombination differ according to their enzyme activities and substrate specificities.
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Affiliation(s)
- Jana Kieper
- Institute of Biochemistry, Faculty of Biology and Chemistry, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 58, 35392 Giessen, Germany
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Song Q, Zhang X. Characterization of a novel non-specific nuclease from thermophilic bacteriophage GBSV1. BMC Biotechnol 2008; 8:43. [PMID: 18439318 PMCID: PMC2390534 DOI: 10.1186/1472-6750-8-43] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2007] [Accepted: 04/28/2008] [Indexed: 11/25/2022] Open
Abstract
Background Thermostable enzymes from thermophiles have attracted extensive studies. In this investigation, a nuclease-encoding gene (designated as GBSV1-NSN) was obtained from a thermophilic bacteriophage GBSV1 for the first time. Results After recombinant expression in Escherichia coli, the purified GBSV1-NSN exhibited non-specific nuclease activity, being able to degrade various nucleic acids, including RNA, single-stranded DNA and double-stranded DNA that was circular or linear. Based on sequence analysis, the nuclease shared no homology with any known nucleases, suggesting that it was a novel nuclease. The characterization of the recombinant GBSV1-NSN showed that its optimal temperature and pH were 60°C and 7.5, respectively. The results indicated that the enzymatic activity was inhibited by enzyme inhibitors or detergents, such as ethylene diamine tetraacetic acid, citrate, dithiothreitol, β-mercaptoethanol, guanidine hydrochloride, urea and SDS. In contrast, the nuclease activity was enhanced by TritonX-100, Tween-20 or chaps to approximately 124.5% – 141.6%. The Km of GBSV1-NSN nuclease was 231, 61 and 92 μM, while its kcat was 1278, 241 and 300 s-1 for the cleavage of dsDNA, ssDNA and RNA, respectively. Conclusion Our study, therefore, presented a novel thermostable non-specific nuclease from thermophilic bacteriophage and its overexpression and purification for scientific research and applications.
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Affiliation(s)
- Qing Song
- Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, The People's Republic of China.
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18
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Wang YT, Yang WJ, Li CL, Doudeva LG, Yuan HS. Structural basis for sequence-dependent DNA cleavage by nonspecific endonucleases. Nucleic Acids Res 2006; 35:584-94. [PMID: 17175542 PMCID: PMC1802626 DOI: 10.1093/nar/gkl621] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Revised: 08/08/2006] [Accepted: 08/08/2006] [Indexed: 12/03/2022] Open
Abstract
Nonspecific endonucleases hydrolyze DNA without sequence specificity but with sequence preference, however the structural basis for cleavage preference remains elusive. We show here that the nonspecific endonuclease ColE7 cleaves DNA with a preference for making nicks after (at 3'O-side) thymine bases but the periplasmic nuclease Vvn cleaves DNA more evenly with little sequence preference. The crystal structure of the 'preferred complex' of the nuclease domain of ColE7 bound to an 18 bp DNA with a thymine before the scissile phosphate had a more distorted DNA phosphate backbone than the backbones in the non-preferred complexes, so that the scissile phosphate was compositionally closer to the endonuclease active site resulting in more efficient DNA cleavage. On the other hand, in the crystal structure of Vvn in complex with a 16 bp DNA, the DNA phosphate backbone was similar and not distorted in comparison with that of a previously reported complex of Vvn with a different DNA sequence. Taken together these results suggest a general structural basis for the sequence-dependent DNA cleavage catalyzed by nonspecific endonucleases, indicating that nonspecific nucleases could induce DNA to deform to distinctive levels depending on the local sequence leading to different cleavage rates along the DNA chain.
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Affiliation(s)
- Yi-Ting Wang
- Institute of Molecular Biology, Academia SinicaTaipei, Taiwan 11529, Republic of China
- Institute of Biochemistry, National Yang-Ming UniversityTaipei, Taiwan, Republic of China
| | - Wei-Jen Yang
- Institute of Molecular Biology, Academia SinicaTaipei, Taiwan 11529, Republic of China
| | - Chia-Lung Li
- Institute of Molecular Biology, Academia SinicaTaipei, Taiwan 11529, Republic of China
| | - Lyudmila G. Doudeva
- Institute of Molecular Biology, Academia SinicaTaipei, Taiwan 11529, Republic of China
| | - Hanna S. Yuan
- Institute of Molecular Biology, Academia SinicaTaipei, Taiwan 11529, Republic of China
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19
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Kriukiene E. Domain organization and metal ion requirement of the Type IIS restriction endonuclease MnlI. FEBS Lett 2006; 580:6115-22. [PMID: 17055493 DOI: 10.1016/j.febslet.2006.09.075] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2006] [Revised: 09/22/2006] [Accepted: 09/28/2006] [Indexed: 11/26/2022]
Abstract
A two-domain structure of the Type IIS restriction endonuclease MnlI has been identified by limited proteolysis. An N-terminal domain of the enzyme mediates the sequence-specific interaction with DNA, whereas a monomeric C-terminal domain resembles bacterial colicin nucleases in its requirement for alkaline earth as well as transition metal ions for double- and single-stranded DNA cleavage activities. The results indicate that the fusion of the non-specific HNH-type nuclease to the DNA binding domain had transformed MnlI into a Mg(2+)-, Ni(2+)-, Co(2+)-, Mn(2+)-, Zn(2+)-, Ca(2+)-dependent sequence-specific enzyme. Nevertheless, MnlI retains a residual single-stranded DNA cleavage activity controlled by its C-terminal colicin-like nuclease domain.
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Affiliation(s)
- Edita Kriukiene
- Institute of Biotechnology, Graiciuno 8, Vilnius LT-02241, Lithuania.
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20
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Calvo E, Ribeiro JMC. A novel secreted endonuclease from Culex quinquefasciatus salivary glands. ACTA ACUST UNITED AC 2006; 209:2651-9. [PMID: 16809456 DOI: 10.1242/jeb.02267] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previous analysis of the salivary gland transcriptome of Culex quinquefasciatus showed the potential presence of an endonuclease with sequence similarities to shrimp, crab and two tsetse salivary proteins. Indeed, not only was the cloned cDNA shown to encode an active double-stranded endonuclease, but also the same activity was demonstrated to be secreted by salivary glands of Cx. quinquefasciatus. Preliminary studies with salivary gland extracts confirmed the presence of a highly active nuclease. This enzyme was shown to be present in the saliva of female mosquitoes by allowing starved mosquitoes to probe DNA-containing agarose gel. The recombinant Cx. quinquefasciatus endonuclease (CuquEndo) produced in mammalian cells showed no sequence specificity for DNA substrate except that it only cleaves double-stranded DNA. Recombinant Cx. quinquefasciatus endonuclease was active in the presence of Mg(2+) ions at pH 7.0-8.0, but no endonuclease activity was detected in the presence of calcium ions. The final hydrolysis products of this enzyme, detected by ion exchange chromatography, yielded DNA fragments ranging form 8-12 base pairs. Although endonucleases have been associated with a variety of cellular functions, their role in mosquito saliva is not clear. This female-specific secreted endonuclease may assist blood meal intake by lowering the local viscosity created by the release of host DNA in the bite site and/or acting as an indirect anticoagulant factor by producing a defibrotide-like mixture of DNA haptamers.
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Affiliation(s)
- Eric Calvo
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Twinbrook III (12735 Twinbrook Parkway), Room 2E-32D, Rockville, MD 20852, USA
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21
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Low RL. Mitochondrial Endonuclease G function in apoptosis and mtDNA metabolism: a historical perspective. Mitochondrion 2005; 2:225-36. [PMID: 16120323 DOI: 10.1016/s1567-7249(02)00104-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2002] [Revised: 10/23/2002] [Accepted: 10/25/2002] [Indexed: 11/24/2022]
Abstract
All mitochondria contain a single, major Mg2+-dependent nuclease capable of extensively degrading DNA and RNA in vitro. This nuclease activity and its gene now go by the name Endonuclease G. For many years, however, a number of different names for this mitochondrial nuclease have been used. This can lead to great deal of confusion for anyone searching the literature. The name Endonuclease G had originally been assigned to an endonuclease activity identified in nuclear extracts of chicken erythrocytes that was found to specifically nick within guanine (G) tracts in DNA in vitro. Subsequent studies however, established that this Endonuclease G activity was identical to the well known, major endonuclease activity isolated from mitochondria of several species. In addition, studies of the mammalian mitochondrial endonuclease showed that the endonuclease is not restricted to only attacking guanine tracts, although it does so avidly. The enzyme is also capable of avidly nicking within cytosine tracts, and at a large variety of sites, that fragments duplex DNA extensively. Despite this, the name Endonuclease G persists. One purpose of this review is to summarize the history of Endonuclease G that spans some 40 years, and review what we have learned about the enzyme's biochemical and biologic properties. Endonuclease G likely serves a role in repair and/or degradation of damaged mtDNA in vivo. Recently, genetic and biochemical evidence has emerged that Endonuclease G is released from the inter membrane space during early stages of programmed cell death, and translocates to the nucleus where it presumably facilitates degradation of chromatin. This exciting new potential role for the enzyme in apoptotic cell death will be discussed.
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Affiliation(s)
- Robert L Low
- Department of Pathology, University of Colorado Health Sciences Center, 4200 East Ninth Avenue, B216, Denver, CO 80262, USA.
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22
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Ghosh M, Meiss G, Pingoud A, London RE, Pedersen LC. Structural insights into the mechanism of nuclease A, a betabeta alpha metal nuclease from Anabaena. J Biol Chem 2005; 280:27990-7. [PMID: 15897201 DOI: 10.1074/jbc.m501798200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nuclease A (NucA) is a nonspecific endonuclease from Anabaena sp. capable of degrading single- and double-stranded DNA and RNA in the presence of divalent metal ions. We have determined the structure of the delta(2-24),D121A mutant of NucA in the presence of Zn2+ and Mn2+ (PDB code 1ZM8). The mutations were introduced to remove the N-terminal signal peptide and to reduce the activity of the nonspecific nuclease, thereby reducing its toxicity to the Escherichia coli expression system. NucA contains a betabeta alpha metal finger motif and a hydrated Mn2+ ion at the active site. Unexpectedly, NucA was found to contain additional metal binding sites approximately 26 A apart from the catalytic metal binding site. A structural comparison between NucA and the closest analog for which structural data exist, the Serratia nuclease, indicates several interesting differences. First, NucA is a monomer rather than a dimer. Second, there is an unexpected structural homology between the N-terminal segments despite a poorly conserved sequence, which in Serratia includes a cysteine bridge thought to play a regulatory role. In addition, although a sequence alignment had suggested that NucA lacks a proposed catalytic residue corresponding to Arg57 in Serratia, the structure determined here indicates that Arg93 in NucA is positioned to fulfill this role. Based on comparison with DNA-bound nuclease structures of the betabeta alpha metal finger nuclease family and available mutational data on NucA, we propose that His124 acts as a catalytic base, and Arg93 participates in the catalysis possibly through stabilization of the transition state.
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Affiliation(s)
- Mahua Ghosh
- Laboratory of Structural Biology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
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23
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Abstract
Single-strand-specific nucleases are multifunctional enzymes and widespread in distribution. Their ability to act selectively on single-stranded nucleic acids and single-stranded regions in double-stranded nucleic acids has led to their extensive application as probes for the structural determination of nucleic acids. Intracellularly, they have been implicated in recombination, repair and replication, whereas extracellular enzymes have a role in nutrition. Although more than 30 single-strand-specific nucleases from various sources have been isolated till now, only a few enzymes (S1 nuclease from Aspergillus oryzae, P1 nuclease from Penicillium citrinum and nucleases from Alteromonas espejiana, Neurospora crassa, Ustilago maydis and mung bean) have been characterized to a significant extent. Recently, some of these enzymes have been cloned, their crystal structures solved and their interactions with different substrates have been established. The detection, purification, characteristics, structure-function correlations, biological role and applications of single-strand-specific nucleases are reviewed.
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Affiliation(s)
- Neelam A Desai
- Division of Biochemical Sciences, National Chemical Laboratory, 411008, Pune, India
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24
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Shagin DA, Rebrikov DV, Kozhemyako VB, Altshuler IM, Shcheglov AS, Zhulidov PA, Bogdanova EA, Staroverov DB, Rasskazov VA, Lukyanov S. A novel method for SNP detection using a new duplex-specific nuclease from crab hepatopancreas. Genome Res 2002; 12:1935-42. [PMID: 12466298 PMCID: PMC187582 DOI: 10.1101/gr.547002] [Citation(s) in RCA: 191] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We have characterized a novel nuclease from the Kamchatka crab, designated duplex-specific nuclease (DSN). DSN displays a strong preference for cleaving double-stranded DNA and DNA in DNA-RNA hybrid duplexes, compared to single-stranded DNA. Moreover, the cleavage rate of short, perfectly matched DNA duplexes by this enzyme is essentially higher than that for nonperfectly matched duplexes of the same length. Thus, DSN differentiates between one-nucleotide variations in DNA. We developed a novel assay for single nucleotide polymorphism (SNP) detection based on this unique property, termed "duplex-specific nuclease preference" (DSNP). In this innovative assay, the DNA region containing the SNP site is amplified and the PCR product mixed with signal probes (FRET-labeled short sequence-specific oligonucleotides) and DSN. During incubation, only perfectly matched duplexes between the DNA template and signal probe are cleaved by DSN to generate sequence-specific fluorescence. The use of FRET-labeled signal probes coupled with the specificity of DSN presents a simple and efficient method for detecting SNPs. We have employed the DSNP assay for the typing of SNPs in methyltetrahydrofolate reductase, prothrombin and p53 genes on homozygous and heterozygous genomic DNA.
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Affiliation(s)
- Dmitry A Shagin
- Shemiakin and Ovchinnikov Institute of Bioorganic Chemistry RAS, 117871 Moscow, Russia
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25
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Kirby TW, Mueller GA, DeRose EF, Lebetkin MS, Meiss G, Pingoud A, London RE. The nuclease A inhibitor represents a new variation of the rare PR-1 fold. J Mol Biol 2002; 320:771-82. [PMID: 12095254 DOI: 10.1016/s0022-2836(02)00460-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Nuclease A (NucA) from Anabaena sp. is a non-specific endonuclease able to degrade single and double-stranded DNA and RNA. The endonucleolytic activity is inhibited by the nuclease A inhibitor (NuiA), which binds to NucA with 1:1 stoichiometry and picomolar affinity. In order to better understand the mechanism of inhibition, the solution structure of NuiA was determined by NMR methods. The fold of NuiA is an alpha-beta-alpha sandwich but standard database searches by DALI and TOP revealed no structural homologies. A visual inspection of alpha-beta-alpha folds in the CATH database revealed similarities to the PR-1-like fold (SCOP nomenclature). The similarities include the ordering of secondary structural elements, a single helix on one face of the alpha-beta-alpha sandwich, and three helices on the other face. However, a major difference is in the IV helix, which in the PR-1 fold is short and perpendicular to the I and III helices, but in NuiA is long and parallel to the I and III helices. Additionally, a strand insertion in the beta-sheet makes the NuiA beta-sheet completely antiparallel in organization. The fast time-scale motions of NuiA, characterized by enhanced flexibility of the extended loop between helices III and IV, also show similarities to P14a, which is a PR-1 fold. We propose that the purpose of the PR-1 fold is to form a stable scaffold to present this extended structure for biological interactions with other proteins. This hypothesis is supported by data that show that when NuiA is bound to NucA significant changes in chemical shift occur in the extended loop between helices III and IV.
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Affiliation(s)
- Thomas W Kirby
- National Institute of Environmental Health Sciences, P.O. Box 12233, MD MR-01, Research Triangle Park, NC 27709, USA
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26
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Scholz SR, Korn C, Gimadutdinow O, Knoblauch M, Pingoud A, Meiss G. The effect of ICAD-S on the formation and intracellular distribution of a nucleolytically active caspase-activated DNase. Nucleic Acids Res 2002; 30:3045-51. [PMID: 12136086 PMCID: PMC135751 DOI: 10.1093/nar/gkf431] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We show here that co-expression of murine CAD with either ICAD-L or ICAD-S in Escherichia coli as well as mammalian cells leads to a functional DFF complex, which after caspase-3 activation releases a nucleolytically active DNase. The chaperone activity of ICAD-S is between one and two orders of magnitude less effective than that of ICAD-L, as deduced from cleavage experiments with different activated recombinant DFF complexes produced in E.coli. With nucleolytically active EGFP fusion proteins of CAD it is demonstrated that co-expression of ICAD-S, which lacks the C-terminal domain of ICAD-L, including the NLS, leads to a homogeneous intracellular distribution of the DNase in transfected cells, whereas co-expression of human or murine ICAD-L variants lacking the NLS leads to exclusion of EGFP-CAD from the nuclei in approximately 50% of cells. These results attribute a particular importance of the NLS in the long isoform of the inhibitor of CAD for nuclear accumulation of the DFF complex in living cells. It is concluded that ICAD-L and ICAD-S in vivo might function as tissue-specific modulators in the regulation of apoptotic DNA degradation by controlling not only the enzymatic activity but also the amount of CAD available in the nuclei of mammalian cells.
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Affiliation(s)
- Sebastian Richard Scholz
- Institut für Biochemie (FB 08), Justus-Liebig-Universität, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany
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27
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Pieper U, Pingoud A. A mutational analysis of the PD...D/EXK motif suggests that McrC harbors the catalytic center for DNA cleavage by the GTP-dependent restriction enzyme McrBC from Escherichia coli. Biochemistry 2002; 41:5236-44. [PMID: 11955073 DOI: 10.1021/bi0156862] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
McrBC is a unique restriction enzyme which binds specifically to the bipartite recognition sequence R(m)CN( approximately )(30)(-)( approximately )(2000)R(m)C and in the presence of GTP translocates the DNA and cleaves both strands at multiple positions within the two R(m)C "half-sites". It is known that McrBC is composed of two subunits: McrB which binds and hydrolyzes GTP and specifically interacts with DNA and McrC whose function is not clear but which has been suspected to harbor the catalytic center for DNA cleavage. A multiple-sequence alignment of the amino acid sequence of Escherichia coli McrC and of six presumably homologous open reading frames from various bacterial species shows that a sequence motif found in many restriction enzymes, but also in other nucleases, the PD.D/EXK motif, is conserved among these sequences. A mutational analysis, in which the carboxylates (aspartic acid in McrC) of this motif were substituted with alanine or asparagine and lysine was substituted with alanine or arginine, strongly suggests that Asp244, Asp257, and Lys259 represent the catalytic center of E. coli McrC. Whereas the variants D244A (or -N), D257A (or -N), and K259A are inactive in DNA cleavage (K259R has residual DNA cleavage activity), they interact with McrB like wild-type McrC, as can be deduced from the finding that they stimulate the McrB-catalyzed GTP hydrolysis to the same extent as wild-type McrC. Thus, whereas McrC variants defective in DNA cleavage can stimulate the GTPase activity of McrB, the DNase activity of McrC is not supported by McrB variants defective in GTP hydrolysis.
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Affiliation(s)
- Uwe Pieper
- Institut für Biochemie (FB 08), Justus-Liebig-Universität, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany
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28
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Pommer AJ, Cal S, Keeble AH, Walker D, Evans SJ, Kühlmann UC, Cooper A, Connolly BA, Hemmings AM, Moore GR, James R, Kleanthous C. Mechanism and cleavage specificity of the H-N-H endonuclease colicin E9. J Mol Biol 2001; 314:735-49. [PMID: 11733993 DOI: 10.1006/jmbi.2001.5189] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Colicin endonucleases and the H-N-H family of homing enzymes share a common active site structural motif that has similarities to the active sites of a variety of other nucleases such as the non-specific endonuclease from Serratia and the sequence-specific His-Cys box homing enzyme I-PpoI. In contrast to these latter enzymes, however, it remains unclear how H-N-H enzymes cleave nucleic acid substrates. Here, we show that the H-N-H enzyme from colicin E9 (the E9 DNase) shares many of the same basic enzymological characteristics as sequence-specific H-N-H enzymes including a dependence for high concentrations of Mg2+ or Ca2+ with double-stranded substrates, a high pH optimum (pH 8-9) and inhibition by monovalent cations. We also show that this seemingly non-specific enzyme preferentially nicks double-stranded DNA at thymine bases producing 3'-hydroxy and 5'-phosphate termini, and that the enzyme does not cleave small substrates, such as dinucleotides or nucleotide analogues, which has implications for its mode of inhibition in bacteria by immunity proteins. The E9 DNase will also bind single-stranded DNA above a certain length and in a sequence-independent manner, with transition metals such as Ni2+ optimal for cleavage but Mg2+ a poor cofactor. Ironically, the H-N-H motif of the E9 DNase although resembling the zinc binding site of a metalloenzyme does not support zinc-mediated hydrolysis of any DNA substrate. Finally, we demonstrate that the E9 DNase also degrades RNA in the absence of metal ions. In the context of current structural information, our data show that the H-N-H motif is an adaptable catalytic centre able to hydrolyse nucleic acid by different mechanisms depending on the substrate and metal ion regime.
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Affiliation(s)
- A J Pommer
- School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
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29
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Abstract
Sugar non-specific endonucleases are multifunctional enzymes and are widespread in distribution. Apart from nutrition, they have also been implicated in cellular functions like replication, recombination and repair. Their ability to recognize different DNA structures has also been exploited for the determination of nucleic acid structure. Although more than 30 non-specific endonucleases have been isolated to date, very little information is available regarding their structure-function correlations except that of staphylococcal and Serratia nucleases. However, during the past few years, the primary structure, nature of the active site based on sequence homology, and the probable mechanism of action have been postulated for some of the enzymes. This review describes the purification, characteristics, biological role and applications of sugar non-specific endonucleases.
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Affiliation(s)
- E S Rangarajan
- Division of Biochemical Sciences, National Chemical Laboratory, Pune 411 008, India
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30
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Brenot A, Werts C, Ottone C, Sertour N, Charon NW, Postic D, Baranton G, Saint Girons I. First evidence for a restriction-modification system in Leptospira sp. FEMS Microbiol Lett 2001; 201:139-43. [PMID: 11470352 DOI: 10.1111/j.1574-6968.2001.tb10747.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The LE1 leptophage exhibited a host range restricted to the saprophytic Leptospira biflexa [Saint Girons et al., Res. Microbiol. 141 (1990) 1131-1133] and mainly to the Patoc 1 strain (hereafter called PFRA) kept in the Paris, France collection. Results of titration of LE1 lysates indicated the presence of a host-controlled modification and restriction system within PUSA (Patoc 1 strain maintained in the Morgantown, WV, USA collection) that was absent in PFRA. Because genomic DNA of PITAL (Patoc 1 strain maintained in Trieste, Italy) appeared smeared in pulsed field gel electrophoresis (PFGE), this strain is likely to contain nucleases that are activated upon DNA isolation. Moreover, comparative NotI digestions of PUSA and PFRA DNAs, as visualized by PFGE, indicated that PUSA belonged to a different serovar than PFRA. Finally, 16S ribosomal sequence analysis indicated that PUSA belonged to the saprophytic Leptospira meyeri species, while PITAL and PFRA appertained to L. biflexa. The evolutionary significance and the importance of the restriction and modification enzymes or non-specific nucleases within strains for genetic experiments are discussed.
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Affiliation(s)
- A Brenot
- Unité de Bactériologie Moléculaire et Médicale, Institut Pasteur, Paris, France
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31
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Gast FU, Franke I, Meiss G, Pingoud A. Immobilization of sugar-non-specific nucleases by utilizing the streptavidin--biotin interaction. J Biotechnol 2001; 87:131-41. [PMID: 11278037 DOI: 10.1016/s0168-1656(01)00230-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Due to their high enzymatic activity, the sugar-non-specific endonucleases from Serratia marcescens and Anabaena can be used for a number of applications, such as the removal of contaminating genetic material from biological preparations, footprinting studies, and the determination of nucleic acids in biochemical samples. These methods would benefit from immobilized nucleases. For this purpose, a single cysteine residue was added at the N-terminus of the Serratia and Anabaena nucleases and subsequently modified with a maleimide-biotin conjugate. Alternatively, a biotin acceptor domain was fused to the Anabaena nuclease, allowing biotinylation during expression in E. coli without a further chemical step. The attachment of biotin-modified nucleases to streptavidin-coated paramagnetic beads and to streptavidin-coated surface plasmon resonance sensor chips (to study interactions with substrate and inhibitor) worked well when aggregates present in the protein preparations were removed by ultrafiltration. These methods should be of general use for similar enzyme systems.
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Affiliation(s)
- F U Gast
- Institut für Biochemie, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 58, D-35292 Giessen, Germany.
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32
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MacLellan SR, Forsberg CW. Properties of the major non-specific endonuclease from the strict anaerobe Fibrobacter succinogenes and evidence for disulfide bond formation in vivo. MICROBIOLOGY (READING, ENGLAND) 2001; 147:315-323. [PMID: 11158348 DOI: 10.1099/00221287-147-2-315] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
DNase A is a non-specific endonuclease of Fibrobacter succinogenes. The enzyme was purified to homogeneity and its properties studied both in vitro and in vivo. Magnesium but not calcium was essential for nucleolytic activity. Manganese ions substituted for magnesium but were less stimulatory. DNase A activity was markedly inhibited by either NaCl or KCl at concentrations greater than 75 mM. The enzyme had a temperature optimum of 25 degrees C and a pH optimum of about 7.0. Values for K:(m) and K:(cat) were determined to be 61 microM and 330 s(-1) respectively, with a catalytic efficiency approximately threefold greater than bovine pancreatic DNase I, but 10-fold less than the Serratia marcescens NucA. DNase A was localized to the periplasm and probably exists as a monomeric species. The enzyme possessed one or more disulfide bonds. In the reduced form it had an apparent mass of 33 kDa, while in the oxidized form it was 29 kDa as estimated by SDS-PAGE. Reduction of the disulfide bonds by dithiothreitol with or without subsequent alkylation by iodoacetamide strongly inactivated the enzyme. DNase A accumulated in vivo had an apparent mass of 29 kDa, indicating that it was in an oxidized form. This is the first indication in a strict anaerobe of a functional periplasmic disulfide bond forming system, phenotypically similar to Dsb systems in facultative and aerobic bacteria.
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Affiliation(s)
- Shawn R MacLellan
- Department of Microbiology, University of Guelph, Guelph, Ontario, CanadaN1G 2W11
| | - Cecil W Forsberg
- Department of Microbiology, University of Guelph, Guelph, Ontario, CanadaN1G 2W11
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Korn C, Meiss G, Gast F, Gimadutdinow O, Urbanke C, Pingoud A. Genetic engineering of Escherichia coli to produce a 1:1 complex of the anabaena sp. PCC 7120 nuclease NucA and its inhibitor NuiA. Gene 2000; 253:221-9. [PMID: 10940560 DOI: 10.1016/s0378-1119(00)00267-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A series of T7-promoter based bicistronic expression vectors was constructed in order to produce the complex of the Anabaena sp. PCC 7120 DNA/RNA non-specific nuclease NucA and its inhibitor NuiA. With all constructs, tandem expression of nucA and nuiA results in aggregation and inclusion body formation of NucA, independent of the order of the genes, the relative expression of the two proteins and the temperature applied during expression. Two constructs in which nuiA is the first and nucA the second cistron lead to an approximately one order of magnitude higher expression of nuiA compared with nucA. In these cells inclusion bodies are formed which contain NucA and NuiA in a 1:1 molar ratio. The complex can be solubilized with 6M urea after disruption of the cells by sonication, renatured by dialysis and purified to homogeneity. 2mg of the complex are obtained from 1l Escherichia coli culture. As shown by gel filtration and analytical ultracentrifugation, our system leads to a highly pure and homogeneous complex preparation, as required for biophysical and structural studies. Thus, our new method is a superior alternative for the production of the NucA/NuiA complex in which separately produced nuclease and inhibitor are mixed, and an excess of one or the other component, as well as aggregates of NucA, have to be removed from the preparation.
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Affiliation(s)
- C Korn
- Institut für Biochemie, Fachbereich Biologie, Chemie und Geowissenschaften, Justus-Liebig-Universität, Heinrich-Buff-Ring 58, D-35392, Giessen, Germany
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Meiss G, Gimadutdinow O, Haberland B, Pingoud A. Mechanism of DNA cleavage by the DNA/RNA-non-specific Anabaena sp. PCC 7120 endonuclease NucA and its inhibition by NuiA. J Mol Biol 2000; 297:521-34. [PMID: 10715218 DOI: 10.1006/jmbi.2000.3586] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A structural model of the DNA/RNA non-specific endonuclease NucA from Anabaena sp. PCC7120 that has been obtained on the basis of the three-dimensional structure of the related Serratia nuclease, suggests that the overall architecture of the active site including amino acid residues H124, N155 and E163 (corresponding to H89, N119 and E127 in Serratia nuclease) is similar in both nucleases. Substitution of these residues by alanine leads to a large reduction in activity (<0.1 %), similarly as observed for Serratia nuclease demonstrating that both enzymes share a similar mechanism of catalysis with differences only in detail. NucA is inhibited by its specific polypeptide inhibitor with a K(i) value in the subpicomolar range, while the related Serratia nuclease at nanomolar concentrations is only inhibited at an approximately 1000-fold molar excess of NuiA. The artificial chromophoric substrate deoxythymidine 3',5'-bis-(p-nitrophenyl phosphate) is cleaved by NucA as well as by Serratia nuclease. Cleavage of this analogue by NucA, however, is not inhibited by NuiA, suggesting that small molecules gain access to the active site of NucA in the enzyme-inhibitor complex under conditions where cleavage of DNA substrates is completely inhibited. The active site residue E163 seems to be the main target amino acid for inhibition of NucA by NuiA, but R93, R122 and R167 (corresponding to K55, R87, R131 in Serratia nuclease) are also involved in the NucA/NuiA interaction. NuiA deletion mutants show that the structural integrity of the N and C-terminal region of the inhibitor is important for complex formation with NucA and inhibition of nuclease activity. Based on these results a mechanism of DNA cleavage by NucA and its inhibition by NuiA is proposed.
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Affiliation(s)
- G Meiss
- Institut für Biochemie, FB08, Justus-Liebig-Universität, Heinrich-Buff-Ring 58, Giessen, D-35392, Germany
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Pieper U, Schweitzer T, Groll DH, Gast FU, Pingoud A. The GTP-binding domain of McrB: more than just a variation on a common theme? J Mol Biol 1999; 292:547-56. [PMID: 10497020 DOI: 10.1006/jmbi.1999.3103] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The methylation-dependent restriction endonuclease McrBC from Escherichia coli K12 cleaves DNA containing two R(m)C dinucleotides separated by about 40 to 2000 base-pairs. McrBC is unique in that cleavage is totally dependent on GTP hydrolysis. McrB is the GTP binding and hydrolyzing subunit, whereas MrC stimulates its GTP hydrolysis. The C-terminal part of McrB contains the sequences characteristic for GTP-binding proteins, consisting of the GxxxxGK(S/T) motif (position 201-208), followed by the DxxG motif (position 300-303). The third motif (NKxD) is present only in a non-canonical form (NTAD 333-336). Here we report a mutational analysis of the putative GTP-binding domain of McrB. Amino acid substitutions were initially performed in the three proposed GTP-binding motifs. Whereas substitutions in motif 1 (P203V) and 2 (D300N) show the expected, albeit modest effects, mutation in the motif 3 is at variance with the expectations. Unlike the corresponding EF-Tu and ras -p21 variants, the D336N mutation in McrB does not change the nucleotide specificity from GTP to XTP, but results in a lack of GTPase stimulation by McrC. The finding that McrB is not a typical G protein motivated us to perform a search for similar sequences in DNA databases. Eight microbial sequences were found, mainly from unfinished sequencing projects, with highly conserved sequence blocks within a presumptive GTP-binding domain. From the five sequences showing the highest homology, 17 invariant charged or polar residues outside the classical three GTP-binding motifs were identified and subsequently exchanged to alanine. Several mutations specifically affect GTP affinity and/or GTPase activity. Our data allow us to conclude that McrB is not a typical member of the superfamily of GTP-binding proteins, but defines a new subfamily within the superfamily of GTP-binding proteins, together with similar prokaryotic proteins of as yet unidentified function.
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Affiliation(s)
- U Pieper
- Institut für Biochemie, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 58, Giessen, D-35392, Germany.
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Miller MD, Cai J, Krause KL. The active site of Serratia endonuclease contains a conserved magnesium-water cluster. J Mol Biol 1999; 288:975-87. [PMID: 10329193 DOI: 10.1006/jmbi.1999.2729] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Serratia endonuclease is an important member of a class of magnesium dependent nucleases that are widely distributed in nature. Here, we describe the location and geometry of a magnesium-water cluster within the active site of this enzyme. The sole protein ligand of the magnesium atom is Asn119; this metal ion is also associated with five water molecules to complete an octahedral coordination complex. These water molecules are very well ordered and there is no evidence of rotational disorder or motion. Glu127 and His89 are located nearby and each is hydrogen bonded to water molecules in the coordination sphere. Asp86 is not chelated to the magnesium or its surrounding water molecules. Results of kinetics and site-specific mutagenesis experiments suggest that this metal-water cluster contains the catalytic metal ion of this enzyme. All residues which hydrogen bond to the water molecules that coordinate the magnesium atom are conserved in nucleases homologous to Serratia endonuclease, suggesting that the water cluster is a conserved feature of this family of enzymes. We offer a detailed structural comparison to one other nuclease, the homing endonuclease I-PpoI, that has recently been shown, in spite of a lack of sequence homology, to share a similar active site geometry to Serratia endonuclease. Evidence from both of these structures suggests that the magnesium of Serratia nuclease participates in catalysis via an inner sphere mechanism.
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Affiliation(s)
- M D Miller
- Department of Biology and Biochemistry, University of Houston, Houston, TX, 77204-5934, USA
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Meiss G, Gast FU, Pingoud AM. The DNA/RNA non-specific Serratia nuclease prefers double-stranded A-form nucleic acids as substrates. J Mol Biol 1999; 288:377-90. [PMID: 10329148 DOI: 10.1006/jmbi.1999.2694] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A steady-state kinetic analysis of the cleavage of the oligonucleotides d(CGCTTTTTTGC) (d(y)), d(GCAAAAAAGCG) (d(r)), r(CGCUUUUUUGC) (r(y)) and r(GCAAAAAAGCG) (r(r)) in single and double-stranded form by the extracellular Serratia marcescens endonuclease, in conjunction with structural data from a circular dichroism spectroscopic analysis of these substrates, suggests that oligonucleotides adopting the A-conformation are preferred over those adopting the B-conformation as substrates. Relative catalytic efficiencies (kcat/KM) for the cleavage of the homo- and heteroduplexes follow the order r(r).r(y) (1.0)>r(r).d(y) (0.9)>d(r). r(y) (0.7)>d(r).d(y) (0.3). The purine-rich single-stranded oligonucleotides r(r) and d(r), are cleaved more efficiently than the pyrimidine-rich oligonucleotides, r(y) and d(y), presumably because they adopt helical structures with pronounced base stacking. Except for the double-stranded oligodeoxynucleotide substrate, the individual strands are cleaved more efficiently when incorporated into a duplex, than in a single-stranded form. Cleavage experiments with various polynucleotides, including a viroid RNA and a specifically designed 167 bp DNA, confirm that double-stranded A-form nucleic acids are preferentially attacked by Serratia nuclease. In an attempt to analyze the basis of these preferences, we have mutated the amino acid residues Tyr76 and Trp123 of Serratia nuclease. These residues are located close to the active site and are conserved in all members of the Serratia nuclease family, suggesting that they could be involved in substrate binding, e.g. by stacking interactions with the bases, which could lead to the cleavage preferences observed. However, only effects on the activity, but no change of the sequence or substrate preferences, were detected upon substitution of these amino acid residues, ruling out any involvement of these residues in the A-form preference of Serratia nuclease.
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Affiliation(s)
- G Meiss
- Institut für Biochemie, Heinrich-Buff-Ring 58, Justus-Liebig-Universität Giessen, D-35392, Germany
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Friedhoff P, Franke I, Krause KL, Pingoud A. Cleavage experiments with deoxythymidine 3',5'-bis-(p-nitrophenyl phosphate) suggest that the homing endonuclease I-PpoI follows the same mechanism of phosphodiester bond hydrolysis as the non-specific Serratia nuclease. FEBS Lett 1999; 443:209-14. [PMID: 9989607 DOI: 10.1016/s0014-5793(98)01660-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We show here that two nucleases, Serratia nuclease and I-PpoI, with contrasting specificities, i.e. non-specific vs. highly sequence specific, share a structurally similar active site region with conservation of the catalytically relevant histidine and asparagine residues. On the basis of a comparison of the available structures and biochemical data for wild type and mutant variants of Serratia nuclease and I-PpoI we propose that both enzymes have a common catalytic mechanism, a proposition that is supported by our finding that both enzymes accept deoxythymidine 3',5'-bis-(p-nitrophenyl phosphate) as a substrate and cleave it in an identical manner. According to this mechanism a histidine residue functions as a general base and Mg2+ bound to an asparagine residue as a Lewis acid in phosphodiester bond cleavage.
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Affiliation(s)
- P Friedhoff
- Institut für Biochemie (FB 15), Justus-Liebig-Universität, Giessen, Germany
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Franke I, Meiss G, Pingoud A. On the advantage of being a dimer, a case study using the dimeric Serratia nuclease and the monomeric nuclease from Anabaena sp. strain PCC 7120. J Biol Chem 1999; 274:825-32. [PMID: 9873021 DOI: 10.1074/jbc.274.2.825] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The extracellular endonucleases from Serratia marcescens and Anabaena sp. are members of a family of nonspecific endonucleases. In contrast to the monomeric Anabaena nuclease, the Serratia nuclease is a dimer of two identical subunits. To find out whether the two active sites of the Serratia nuclease function independently of each other and what the advantage of being a dimer for this enzyme might be, we produced (i) dimers in which the two subunits were cross-linked, (ii) heterodimers consisting of a wild type and an inactive mutant subunit which were also cross-linked, and (iii) monomeric variants which are unable to dimerize. The monomeric H184R variant and the cross-linked S140C variant exhibit the same activity as the wild type enzyme, while the cross-linked heterodimer with one inactive subunit shows only half of the activity of the wild type enzyme, demonstrating functional independence of the two subunits of the Serratia nuclease. On the other hand at low enzyme and substrate concentrations dimeric forms of the Serratia nuclease are relatively more active than monomeric forms or the monomeric Anabaena nuclease in cleaving polynucleotides, not, however, oligonucleotides, which is correlated with the ability of dimeric forms of the Serratia nuclease to form large enzyme-substrate networks with high molecular weight DNA and to cleave polynucleotides in a processive manner. We conclude that in the natural habitat of Serratia marcescens where the supply of nutrients may become growth limiting the dimeric nuclease can fulfil its nutritive function more efficiently than a monomeric enzyme.
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Affiliation(s)
- I Franke
- Institut für Biochemie, Fachbereich Biologie, Justus-Liebig Universität, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany
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Franke I, Pingoud A. Synthesis and biochemical characterization of obligatory dimers of the sugar non-specific nuclease from Serratia marcescens using specifically designed bismaleimidoalkanes as SH-specific crosslinking reagents. JOURNAL OF PROTEIN CHEMISTRY 1999; 18:137-46. [PMID: 10071938 DOI: 10.1023/a:1020616020507] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The genetically engineered S140C variant of the homodimeric nuclease from Serratia marcescens was crosslinked across the dimer interface at the Cys 140 residues using bifunctional SH-specific 1,1'-alkanediyl-bis-pyrrole-2,5-diones of different lengths. These bismaleimidoalkanes were synthesized by the condensation of n-alkyldiamines with maleic anhydride and subsequent cyclization with acetic anhydride and sodium acetate. Bismaleimidohexane (BMH) which gave the best crosslinking yield was used to produce in preparative amounts crosslinked Serratia nuclease. The crosslinked protein has the same secondary structure and exhibits the same guanidinium chloride unfolding behavior as the wild type enzyme or the non-covalently linked S 140C variant. In contrast, in thermal unfolding experiments the crosslinked dimer behaves differently from the wild type enzyme or the non-covalently linked S140C variant. CD-spectra recorded during temperature rise showed only minor changes of the secondary structure composition for the wild type enzyme and the non-covalently linked S140C variant, whereas in the case of the crosslinked S140C dimer a distinct increase of the CD effect was observed corresponding to an increase in alpha-helix. Our results demonstrate that bismaleimidoalkanes are very well suited to covalently link subunits of proteins, provided suitably located cysteine residues are present.
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Affiliation(s)
- I Franke
- Institut für Biochemie (FB 15) Justus-Liebig Universität, Giessen, Germany
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