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Arakawa T, Kawano Y, Kataoka S, Katayama Y, Kamiya N, Yohda M, Odaka M. Structure of Thiocyanate Hydrolase: A New Nitrile Hydratase Family Protein with a Novel Five-coordinate Cobalt(III) Center. J Mol Biol 2007; 366:1497-509. [PMID: 17222425 DOI: 10.1016/j.jmb.2006.12.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2006] [Revised: 12/01/2006] [Accepted: 12/05/2006] [Indexed: 10/23/2022]
Abstract
Thiocyanate hydrolase (SCNase) of Thiobacillus thioparus THI115 is a cobalt(III)-containing enzyme catalyzing the degradation of thiocyanate to carbonyl sulfide and ammonia. We determined the crystal structures of the apo- and native SCNases at a resolution of 2.0 A. SCNases in both forms had a conserved hetero-dodecameric structure, (alphabetagamma)(4). Four alphabetagamma hetero-trimers were structurally equivalent. One alphabetagamma hetero-trimer was composed of the core domain and the betaN domain, which was located at the center of the molecule and linked the hetero-trimers with novel quaternary interfaces. In both the apo- and native SCNases, the core domain was structurally conserved between those of iron and cobalt-types of nitrile hydratase (NHase). Native SCNase possessed the post-translationally modified cysteine ligands, gammaCys131-SO(2)H and gammaCys133-SOH like NHases. However, the low-spin cobalt(III) was found to be in the distorted square-pyramidal geometry, which had not been reported before in any protein. The size as well as the electrostatic properties of the substrate-binding pocket was totally different from NHases with respect to the charge distribution and the substrate accessibility, which rationally explains the differences in the substrate preference between SCNase and NHase.
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Affiliation(s)
- Takatoshi Arakawa
- Department of Biotechnology and Life Science, Graduate School of Technology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan
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52
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Sari MA, Jaouen M, Saroja NR, Artaud I. Influence of cobalt substitution on the activity of iron-type nitrile hydratase: are cobalt type nitrile hydratases regulated by carbon monoxide? J Inorg Biochem 2006; 101:614-22. [PMID: 17267045 DOI: 10.1016/j.jinorgbio.2006.12.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2006] [Revised: 12/07/2006] [Accepted: 12/08/2006] [Indexed: 11/15/2022]
Abstract
Comamonas testosteroni Ni1 nitrile hydratase is a Fe-type nitrile hydratase whose native and recombinant forms are identical. Here, the iron of Ni1 nitrile hydratase was replaced by cobalt using a chaperone based Escherichia coli expression system. Cobalt (CoNi1) and iron (FeNi1) enzymes share identical Vmax (30 nmol min(-1) mg(-1)) and Km (200 microM) toward their substrate and identical Ki values for the known competitive inhibitors of FeNi1. However, nitrophenols used as inhibitors do display a different inhibition pattern on both enzymes. Furthermore, CoNi1 and FeNi1 are also different in their sensitivity to nitric oxide and carbon monoxide, CO being selective of the cobalt enzyme. These differences are rationalized in relation to the nature of the catalytic metal center in the enzyme.
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Affiliation(s)
- Marie-Agnès Sari
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Université René Descartes, UMR 8601 CNRS, 45 Rue des Saint-Pères, 75270 Paris Cedex 06, France.
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53
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Lugo-Mas P, Dey A, Xu L, Davin SD, Benedict J, Kaminsky W, Hodgson KO, Hedman B, Solomon EI, Kovacs JA. How does single oxygen atom addition affect the properties of an Fe-nitrile hydratase analogue? The compensatory role of the unmodified thiolate. J Am Chem Soc 2006; 128:11211-21. [PMID: 16925440 PMCID: PMC4481871 DOI: 10.1021/ja062706k] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nitrile hydratase (NHase) is one of a growing number of enzymes shown to contain post-translationally modified cysteine sulfenic acids (Cys-SOH). Cysteine sulfenic acids have been shown to play diverse roles in cellular processes, including transcriptional regulation, signal transduction, and the regulation of oxygen metabolism and oxidative stress responses. The function of the cysteine sulfenic acid coordinated to the iron active site of NHase is unknown. Herein we report the first example of a sulfenate-ligated iron complex, [Fe(III)(ADIT)(ADIT-O)](+) (5), and compare its electronic and magnetic properties with those of structurally related complexes in which the sulfur oxidation state and protonation state have been systematically altered. Oxygen atom addition was found to decrease the unmodified thiolate Fe-S bond length and blue-shift the ligand-to-metal charge-transfer band (without loss of intensity). S K-edge X-ray absorption spectroscopy and density functional theory calculations show that, although the modified RS-O(-) fragment is incapable of forming a pi bond with the Fe(III) center, the unmodified thiolate compensates for this loss of pi bonding by increasing its covalent bond strength. The redox potential shifts only slightly (75 mV), and the magnetic properties are not affected (the S = (1)/(2) spin state is maintained). The coordinated sulfenate S-O bond is activated and fairly polarized (S(+)-O(-)). Addition of strong acids at low temperatures results in the reversible protonation of sulfenate-ligated 5. An X-ray structure demonstrates that Zn(2+) binds to the sulfenate oxygen to afford [Fe(III)(ADIT)(ADIT-O-ZnCl(3))] (6). The coordination of ZnCl(3)(-) to the RS-O(-) unit causes the covalent overlap with the unmodified thiolate to increase further. A possible catalytic role for the unmodified NHase thiolate, involving its ability to "tune" the electronics in response to protonation of the sulfenate (RS-O(-)) oxygen and/or substrate binding, is discussed.
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Affiliation(s)
- Priscilla Lugo-Mas
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, USA
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54
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Kataoka S, Arakawa T, Hori S, Katayama Y, Hara Y, Matsushita Y, Nakayama H, Yohda M, Nyunoya H, Dohmae N, Maeda M, Odaka M. Functional expression of thiocyanate hydrolase is promoted by its activator protein, P15K. FEBS Lett 2006; 580:4667-72. [PMID: 16879822 DOI: 10.1016/j.febslet.2006.07.051] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2006] [Revised: 07/14/2006] [Accepted: 07/14/2006] [Indexed: 10/24/2022]
Abstract
Thiocyanate hydrolase (SCNase) is a cobalt-containing enzyme with a post-translationally modified cysteine ligand, gammaCys131-SO(2)H. When the SCNase alpha, beta and gamma subunits were expressed in Escherichia coli, the subunits assembled to form a hetero-dodecamer, (alphabetagamma)(4), like native SCNase but exhibited no catalytic activity. Metal analysis indicated that SCNase was expressed as an apo-form irrespective of the presence of cobalt in the medium. On the contrary, SCNase co-expressed with P15K, encoded just downstream of SCNase genes, in cobalt-enriched medium under the optimized condition (SCNase((+P15K))) possessed 0.86 Co atom/alphabetagamma trimer and exhibited 78% of the activity of native SCNase. SCNase((+P15K)) showed a UV-Vis absorption peak characteristic of the SCNase cobalt center. About 70% of SCNase((+P15K)) had the gammaCys131-SO(2)H modification. These results indicate that SCNase((+P15K)) is the active holo-SCNase. P15K is likely to promote the functional expression of SCNase probably by assisting the incorporation of cobalt ion.
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Affiliation(s)
- Shingo Kataoka
- Department of Biotechnology and Life Science, Graduate School of Technology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan
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55
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Greene SN, Richards NGJ. Electronic structure, bonding, spectroscopy and energetics of Fe-dependent nitrile hydratase active-site models. Inorg Chem 2006; 45:17-36. [PMID: 16390037 DOI: 10.1021/ic050965p] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Fe-type nitrile hydratase (NHase) is a non-heme Fe(III)-dependent enzyme that catalyzes the hydration of nitriles to the corresponding amides. Despite experimental studies of the enzyme and model Fe(III)-containing complexes, many questions concerning the electronic structure and spectroscopic transitions of the metal center remain unanswered. In addition, the catalytic mechanism of nitrile hydration has not yet been determined. We now report density functional theory (B3LYP/6-31G) calculations on three models of the Fe(III) center in the active site of NHase corresponding to hypothetical intermediates in the enzyme-catalyzed hydration of acetonitrile. Together with natural bond orbital (NBO) analysis of the chemical bonding in these active-site models and INDO/S CIS calculations of their electronic spectra, this theoretical investigation gives new insight into the molecular origin of the unusual low-spin preference and spectroscopic properties of the Fe(III) center. In addition, the low-energy electronic transition observed for the active form of NHase is assigned to a dd transition that is coupled with charge-transfer transitions involving the metal and its sulfur ligands. Calculations of isodesmic ligand-exchange reaction energies provide support for coordination of the Fe(III) center in free NHase by a water molecule rather than a hydroxide ion and suggest that the activation of the nitrile substrate by binding to the metal in the sixth coordination site during catalytic turnover cannot yet be definitively ruled out.
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Affiliation(s)
- Shannon N Greene
- Department of Chemistry, University of Florida, Gainesville, 32611-7200, USA
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56
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Dey A, Chow M, Taniguchi K, Lugo-Mas P, Davin S, Maeda M, Kovacs JA, Odaka M, Hodgson KO, Hedman B, Solomon EI. Sulfur K-edge XAS and DFT calculations on nitrile hydratase: geometric and electronic structure of the non-heme iron active site. J Am Chem Soc 2006; 128:533-41. [PMID: 16402841 PMCID: PMC4485618 DOI: 10.1021/ja0549695] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The geometric and electronic structure of the active site of the non-heme iron enzyme nitrile hydratase (NHase) is studied using sulfur K-edge XAS and DFT calculations. Using thiolate (RS(-))-, sulfenate (RSO(-))-, and sulfinate (RSO(2)(-))-ligated model complexes to provide benchmark spectral parameters, the results show that the S K-edge XAS is sensitive to the oxidation state of S-containing ligands and that the spectrum of the RSO(-) species changes upon protonation as the S-O bond is elongated (by approximately 0.1 A). These signature features are used to identify the three cysteine residues coordinated to the low-spin Fe(III) in the active site of NHase as CysS(-), CysSOH, and CysSO(2)(-) both in the NO-bound inactive form and in the photolyzed active form. These results are correlated to geometry-optimized DFT calculations. The pre-edge region of the X-ray absorption spectrum is sensitive to the Z(eff) of the Fe and reveals that the Fe in [FeNO](6) NHase species has a Z(eff) very similar to that of its photolyzed Fe(III) counterpart. DFT calculations reveal that this results from the strong pi back-bonding into the pi antibonding orbital of NO, which shifts significant charge from the formally t(2)(6) low-spin metal to the coordinated NO.
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Affiliation(s)
- Abhishek Dey
- Department of Chemistry, Stanford University, Stanford, California 94305
| | - Marina Chow
- Department of Chemistry, Stanford University, Stanford, California 94305
| | | | - Priscilla Lugo-Mas
- Department of Chemistry, University of Washington, Seattle, Washington 98195
| | - Steven Davin
- Department of Chemistry, University of Washington, Seattle, Washington 98195
| | - Mizuo Maeda
- Bioengineering Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Julie A. Kovacs
- Department of Chemistry, University of Washington, Seattle, Washington 98195
| | - Masafumi Odaka
- Bioengineering Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Keith O. Hodgson
- Department of Chemistry, Stanford University, Stanford, California 94305
- Stanford Synchrotron Radiation Laboratory, SLAC, Stanford University, Stanford, California 94309
| | - Britt Hedman
- Stanford Synchrotron Radiation Laboratory, SLAC, Stanford University, Stanford, California 94309
| | - Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305
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57
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Kato Y, Yoshida S, Xie SX, Asano Y. Aldoxime dehydratase co-existing with nitrile hydratase and amidase in the iron-type nitrile hydratase-producer Rhodococcus sp. N-771. J Biosci Bioeng 2005; 97:250-9. [PMID: 16233624 DOI: 10.1016/s1389-1723(04)70200-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2003] [Accepted: 01/26/2004] [Indexed: 10/26/2022]
Abstract
We identified an aldoxime dehydratase (Oxd) gene in the 5'-flanking region of the nitrile hydratase-amidase gene cluster in the photoreactive iron-type nitrile hydratase-producer, Rhodococcus sp. N-771. The enzyme showed 96.3%, 77.6%, and 30.4% identities with the Oxds of Rhodococcus globerulus A-4, Pseudomonas chlororaphis B23, and Bacillus sp. OxB-1, respectively. The enzyme was expressed in Escherichia coli under the control of the lac- or T7 promoters in its intact and His6-tagged forms, purified, and characterized. The enzyme had heme b as a prosthetic group, catalyzed a stoichiometric dehydration of aldoxime into nitrile, and exhibited the highest activity at neutral pH and at around 30 degrees C similar to the known Oxd from Bacillus sp. OxB-1. The activity was enhanced by reducing agents, such as Na2S, Na2S2(O4), 2-mercaptoethanol, and L-cysteine and supplementary additions of electron acceptors such as flavins, sulfite ion, and vitamin K3. The effect of various chemicals on the enzyme activity was different in the presence and absence of the reducing reagent, Na2S. The enzyme preferentially acts on aliphatic-type substrates and the substrate specificity of the enzyme coincides with that reported for nitrile hydratase produced by the strain.
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Affiliation(s)
- Yasuo Kato
- Biotechnology Research Center, Faculty of Engineering, Toyama Prefectural University, 5180 Kurokawa, Kosugi, Toyama 939-0398, Japan
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58
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Bourles E, Alves de Sousa R, Galardon E, Giorgi M, Artaud I. Direct Synthesis of a Thiolato-S and Sulfinato-S CoIII Complex Related to the Active Site of Nitrile Hydratase: A Pathway to the Post-Translational Oxidation of the Protein. Angew Chem Int Ed Engl 2005; 44:6162-5. [PMID: 16136617 DOI: 10.1002/anie.200500814] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Emilie Bourles
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR8601 CNRS, Université René Descartes, 45 rue des Sts pères, 75270 Paris Cedex 06, France
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59
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Bourles E, Alves de Sousa R, Galardon E, Giorgi M, Artaud I. Direct Synthesis of a Thiolato-S and Sulfinato-S CoIII Complex Related to the Active Site of Nitrile Hydratase: A Pathway to the Post-Translational Oxidation of the Protein. Angew Chem Int Ed Engl 2005. [DOI: 10.1002/ange.200500814] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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60
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Cameron RA, Sayed M, Cowan DA. Molecular analysis of the nitrile catabolism operon of the thermophile Bacillus pallidus RAPc8. Biochim Biophys Acta Gen Subj 2005; 1725:35-46. [PMID: 15955632 DOI: 10.1016/j.bbagen.2005.03.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2004] [Revised: 03/24/2005] [Accepted: 03/28/2005] [Indexed: 11/19/2022]
Abstract
The gene cluster containing the nitrile hydratase (NHase) and amidase genes of a moderate thermophile, B. pallidus RAPc8 has been cloned and sequenced. The (5.9 kb) section of cloned DNA contained eight complete open reading frames, encoding (in order), amidase (belonging to the nitrilase related aliphatic amidase family), nitrile hydratase beta and alpha subunits (of the cobalt containing class), a 122-amino acid accessory protein, designated P14K, a homologue of the 2Fe-2S class of ferredoxins and three putative proteins with distinct homology to the cobalt uptake proteins cbiM, cbiN and cbiQ of the S. typhimurium LT2 cobalamin biosynthesis pathway. The amidase and nitrile hydratase genes were subcloned and inducibly expressed in Escherichia coli, to levels of approximately 37 U/mg and 49 U/mg, respectively, without the co-expression of additional flanking genes. However, co-expression of P14K with the NHase structural genes significantly enhanced the specific activity of the recombinant NHase. This is the first description of an accessory protein involved in thermostable NHase expression. Modelling of the P14K protein structure has suggested that this protein functions as a subunit-specific chaperone, aiding in the folding of the NHase alpha subunit prior to alpha-beta subunit association and the formation of alpha(2)beta(2) NHase holoenzyme.
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Affiliation(s)
- Rory A Cameron
- Advanced Research Centre for Applied Microbiology, Department of Biotechnology, University of the Western Cape, Bellville 7535, Cape Town, South Africa
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61
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Mersinger L, Hann E, Cooling F, Gavagan J, Ben-Bassat A, Wu S, Petrillo K, Payne M, DiCosimo R. Production of Acrylamide using Alginate-ImmobilizedE. coli ExpressingComamonas testosteroni 5-MGAM-4D Nitrile Hydratase. Adv Synth Catal 2005. [DOI: 10.1002/adsc.200505039] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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62
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O'Mahony R, Doran J, Coffey L, Cahill OJ, Black GW, O'Reilly C. Characterisation of the nitrile hydratase gene clusters of Rhodococcus erythropolis strains AJ270 and AJ300 and Microbacterium sp. AJ115 indicates horizontal gene transfer and reveals an insertion of IS1166. Antonie van Leeuwenhoek 2005; 87:221-32. [PMID: 15803388 DOI: 10.1007/s10482-004-3721-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2004] [Accepted: 09/23/2004] [Indexed: 10/25/2022]
Abstract
The nitrile metabolising strains AJ270, AJ300 and AJ115 were isolated from the same location. The strains have very similar nitrile metabolising profiles. Sequencing of the 16S rRNA gene indicates that strains AJ270 and AJ300 are novel strains of Rhodococcus erythropolis while strain AJ115 is a novel Microbacterium strain very closely related to Microbacterium oxydans and Microbacterium liquefaciens. Analysis of the structure of the nitrile hydratase/amidase gene clusters in the three strains indicates that this region is identical in these strains and that this structure is different to other nitrile hydratase/amidase gene clusters. The major difference seen is the insertion of a complete copy of the insertion sequence IS1166 in the nhr2 gene. This copy of IS1166 generates a 10 bp direct duplication at the point of insertion and has one ORF encoding a protein of 434 amino acids, with 98% homology to the transposase of IS666 from Mycobacterium avium. A gene oxd, encoding aldoxime dehydratase is found upstream of the nitrile hydratase gene cluster and an open reading frame encoding a protein with homology to GlnQ type ABC transporters is found downstream of the nitrile hydratase/amidase genes. The identity of the nitrile hydratase/amidase gene clusters in the three strains suggests horizontal gene transfer of this region. Analysis of the strains for both linear and circular plasmids indicates that both are present in the strains but hybridisation studies indicate that the nitrile hydratase/amidase gene cluster is chromosomally located. The nitrile hydratase/amidase enzymes of strain AJ270 are inducible with acetonitrile or acetamide. Interestingly although a number of Fe-type nitrile hydratases have been shown to be photosensitive, the enzyme from strain AJ270 is not.
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Affiliation(s)
- Rebecca O'Mahony
- Department of Chemical and Life Sciences, Waterford Institute of Technology, Cork Road, Waterford, Ireland
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63
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Greene SN, Richards NGJ. Theoretical investigations of the electronic structure and spectroscopy of mononuclear, non-heme [Fe-NO](6) complexes. Inorg Chem 2004; 43:7030-41. [PMID: 15500340 DOI: 10.1021/ic0499695] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The unusual metal coordination and spin-state of the Fe(III) center in nitrile hydratase (NHase) has stimulated the synthesis of numerous model complexes in efforts to understand the reactivity and spectroscopic properties of the enzyme. A particular problem has been the development of model Fe(III) complexes that exhibit reversible, photolabile binding to nitric oxide (NO) in a manner similar to that observed for the NHase metal center. We now report a detailed NBO analysis of the ground-state chemical bonding in three [Fe-NO](6) complexes that exhibit different responses to irradiation, together with investigations of their spectroscopic properties using semiempirical INDO/S CI singles calculations. Our computational studies reveal a correlation between the photolability of these complexes and the existence of low-energy transitions that promote an electron into the Fe-NO pi(*) antibonding molecular orbital. In addition to providing detailed insights into how the ligand field influences the spectroscopy of these mononuclear complexes, these studies strengthen our previous conclusions regarding the role of post-translational cysteine modification in modulating the photoreactivity of the inactive, NO complex of NHase.
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Affiliation(s)
- Shannon N Greene
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, USA
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64
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Liebeton K, Eck J. Identification and Expression inE. coli of Novel Nitrile Hydratases from the Metagenome. Eng Life Sci 2004. [DOI: 10.1002/elsc.200402156] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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65
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Reisinger C, Osprian I, Glieder A, Schoemaker HE, Griengl H, Schwab H. Enzymatic hydrolysis of cyanohydrins with recombinant nitrile hydratase and amidase from hodococcus erythropolis. Biotechnol Lett 2004; 26:1675-80. [PMID: 15604819 DOI: 10.1007/s10529-004-3521-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Nitrile hydratase and amidase from Rhodococcus erythropolis CIMB11540 were both cloned and expressed in Escherichia coli. Crude cell free extracts were used for the hydrolysis of different aromatic cyanohydrins. Nitrile hydratase expression was increased up to 5-fold by redesign of the expression cassette. The recombinant enzymes were successfully used for the conversion of several cyanohydrins to the corresponding alpha-hydroxy amides and acids while retaining enantiopurity.
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Affiliation(s)
- Ch Reisinger
- Institute of Molecular Biotechnology, Graz University of Technology, Petersgasse 14, Graz, 8010, Austria
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66
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Kovacs JA. Synthetic analogues of cysteinate-ligated non-heme iron and non-corrinoid cobalt enzymes. Chem Rev 2004; 104:825-48. [PMID: 14871143 PMCID: PMC4487544 DOI: 10.1021/cr020619e] [Citation(s) in RCA: 224] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Julie A Kovacs
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, USA
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67
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Miyanaga A, Fushinobu S, Ito K, Shoun H, Wakagi T. Mutational and structural analysis of cobalt-containing nitrile hydratase on substrate and metal binding. ACTA ACUST UNITED AC 2004; 271:429-38. [PMID: 14717710 DOI: 10.1046/j.1432-1033.2003.03943.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mutants of a cobalt-containing nitrile hydratase (NHase, EC 4.2.1.84) from Pseudonocardia thermophila JCM 3095 involved in substrate binding, catalysis and formation of the active center were constructed, and their characteristics and crystal structures were investigated. As expected from the structure of the substrate binding pocket, the wild-type enzyme showed significantly lower K(m) and K(i) values for aromatic substrates and inhibitors, respectively, than aliphatic ones. In the crystal structure of a complex with an inhibitor (n-butyric acid) the hydroxyl group of betaTyr68 formed hydrogen bonds with both n-butyric acid and alphaSer112, which is located in the active center. The betaY68F mutant showed an elevated K(m) value and a significantly decreased k(cat) value. The apoenzyme, which contains no detectable cobalt atom, was prepared from Escherichia coli cells grown in medium without cobalt ions. It showed no detectable activity. A disulfide bond between alphaCys108 and alphaCys113 was formed in the apoenzyme structure. In the highly conserved sequence motif in the cysteine cluster region, two positions are exclusively conserved in cobalt-containing or iron-containing nitrile hydratases. Two mutants (alphaT109S and alphaY114T) were constructed, each residue being replaced with an iron-containing one. The alphaT109S mutant showed similar characteristics to the wild-type enzyme. However, the alphaY114T mutant showed a very low cobalt content and catalytic activity compared with the wild-type enzyme, and oxidative modifications of alphaCys111 and alphaCys113 residues were not observed. The alphaTyr114 residue may be involved in the interaction with the nitrile hydratase activator protein of P. thermophila.
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68
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Lu J, Zheng Y, Yamagishi H, Odaka M, Tsujimura M, Maeda M, Endo I. Motif CXCC in nitrile hydratase activator is critical for NHase biogenesis in vivo. FEBS Lett 2003; 553:391-6. [PMID: 14572657 DOI: 10.1016/s0014-5793(03)01070-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Nitrile hydratase (NHase) activator from Rhodococcus sp. N-771 is required for NHase functional expression. The motif 73CXCC76 in the NHase activator sequence was here revealed to be vital for its function by site-directed mutagenesis. All three substitutions of the cysteines by serines resulted in a much lower level of expression of active NHase. Furthermore, interaction between NHase activator and NHase was detected and the critical role of NHase activator was not exhibited in the cysteine oxidization process of NHase. These findings suggest NHase activator mainly participates in iron trafficking in NHase biogenesis as an iron type metallochaperone.
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Affiliation(s)
- Jun Lu
- The Institute of Physical and Chemical Research, Wako Shi, 351-0198 Saitama, Japan.
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Cowan DA, Cameron RA, Tsekoa TL. Comparative biology of mesophilic and thermophilic nitrile hydratases. ADVANCES IN APPLIED MICROBIOLOGY 2003; 52:123-58. [PMID: 12964242 DOI: 10.1016/s0065-2164(03)01005-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Don A Cowan
- Advanced Research Centre for Applied Microbiology, Department of Biotechnology, University of the Western Cape, Bellville 7535, Cape Town, South Africa
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70
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Brandão PFB, Clapp JP, Bull AT. Diversity of nitrile hydratase and amidase enzyme genes in Rhodococcus erythropolis recovered from geographically distinct habitats. Appl Environ Microbiol 2003; 69:5754-66. [PMID: 14532022 PMCID: PMC201182 DOI: 10.1128/aem.69.10.5754-5766.2003] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2003] [Accepted: 07/09/2003] [Indexed: 11/20/2022] Open
Abstract
A molecular screening approach was developed in order to amplify the genomic region that codes for the alpha- and beta-subunits of the nitrile hydratase (NHase) enzyme in rhodococci. Specific PCR primers were designed for the NHase genes from a collection of nitrile-degrading actinomycetes, but amplification was successful only with strains identified as Rhodococcus erythropolis. A hydratase PCR product was also obtained from R. erythropolis DSM 43066(T), which did not grow on nitriles. Southern hybridization of other members of the nitrile-degrading bacterial collection resulted in no positive signals other than those for the R. erythropolis strains used as positive controls. PCR-restriction fragment length polymorphism-single-strand conformational polymorphism (PRS) analysis of the hydratases in the R. erythropolis strains revealed unique patterns that mostly correlated with distinct geographical sites of origin. Representative NHases were sequenced, and they exhibited more than 92.4% similarity to previously described NHases. The phylogenetic analysis and deduced amino acid sequences suggested that the novel R. erythropolis enzymes belonged to the iron-type NHase family. Some different residues in the translated sequences were located near the residues involved in the stabilization of the NHase active site, suggesting that the substitutions could be responsible for the different enzyme activities and substrate specificities observed previously in this group of actinomycetes. A similar molecular screening analysis of the amidase gene was performed, and a correlation between the PRS patterns and the geographical origins identical to the correlation found for the NHase gene was obtained, suggesting that there was coevolution of the two enzymes in R. erythropolis. Our findings indicate that the NHase and amidase genes present in geographically distinct R. erythropolis strains are not globally mixed.
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Affiliation(s)
- Pedro F B Brandão
- Research School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, United Kingdom
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71
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Xie SX, Kato Y, Komeda H, Yoshida S, Asano Y. A Gene Cluster Responsible for Alkylaldoxime Metabolism Coexisting with Nitrile Hydratase and Amidase in Rhodococcus globerulus A-4,. Biochemistry 2003; 42:12056-66. [PMID: 14556637 DOI: 10.1021/bi035092u] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An enzyme "alkylaldoxime dehydratase (OxdRG)" was purified and characterized from Rhodococcus globerulus A-4, in which nitrile hydratase (NHase) and amidase coexisted with the enzyme. The enzyme contains heme b as a prosthetic group, requires reducing reagents for the reaction, and is most active at a neutral pH and at around 30 degrees C, similar to the phenylacetaldoxime dehydratase from Bacillus sp. OxB-1 (OxdB). However, some differences were seen in subunit structure, substrate specificity, and effects of activators and inhibitors. The corresponding gene, oxd, encoding a 1059-base pair ORF consisting of 353 codons, was cloned, sequenced, and overexpressed in Escherichia coli. The predicted polypeptide showed 30.3% identity to OxdB. The gene is mapped just upstream of the gene cluster encoding the enzymes involved in the metabolism of aliphatic nitriles, i.e., NHase and amidase, and their regulatory and activator proteins. We report here the existence of an aldoxime dehydratase genetically linked with NHase and amidase, and responsible for the metabolism of alkylaldoxime in R. globerulus.
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Affiliation(s)
- Sheng-Xue Xie
- Biotechnology Research Center, Faculty of Engineering, Toyama Prefectural University, 5180 Kurokawa, Kosugi, Toyama 939-0398, Japan
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72
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Tsujimura M, Odaka M, Nakayama H, Dohmae N, Koshino H, Asami T, Hoshino M, Takio K, Yoshida S, Maeda M, Endo I. A novel inhibitor for Fe-type nitrile hydratase: 2-cyano-2-propyl hydroperoxide. J Am Chem Soc 2003; 125:11532-8. [PMID: 13129355 DOI: 10.1021/ja035018z] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nitrile hydratase (NHase) is a non-heme iron or non-corrin cobalt enzyme having two post-translationally modified ligand residues, cysteine-sulfinic acid (alphaCys112-SO(2)H) and -sulfenic acid (alphaCys114-SOH). We studied the interaction between Fe-type NHase and isobutyronitrile (iso-BN) which had been reported as a competitive inhibitor with a K(i) value of 5 microM. From detailed kinetic studies of the inhibitory effect of iso-BN on Fe-type NHase, we found that authentic iso-BN was hydrated normally and that the impurity present in commercially available iso-BN inhibited NHase activity strongly. The inhibitory compound induced significant changes in the UV-vis absorption spectrum of NHase, suggesting its interaction with the iron center. This compound was purified by using reversed-phase HPLC and identified as 2-cyano-2-propyl hydroperoxide (Cpx) by (1)H and PFG-HMBC NMR spectroscopy. Upon addition of a stoichiometric amount of Cpx, NHase was irreversibly inactivated, probably by the oxidation of alphaCys114-SOH to Cys-SO(2)H. This result suggests that the -SOH structure of alphaCys114 is essential for the catalytic activity. The oxygen atom in Cys-SO(2)H is confirmed to come from the solvent H(2)O. The oxidized NHase was found to induce the UV-vis absorption spectral changes by addition of Cpx, suggesting that Cpx strongly interacted with iron(III) in the oxidized NHase to form a stable complex. Thus, Cpx functions as a novel irreversible inhibitor for NHase.
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Affiliation(s)
- Masanari Tsujimura
- Biomolecular Characterization Division, RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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73
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Stevens JM, Belghazi M, Jaouen M, Bonnet D, Schmitter JM, Mansuy D, Sari MA, Artaud I. Post-translational modification of Rhodococcus R312 and Comamonas NI1 nitrile hydratases. JOURNAL OF MASS SPECTROMETRY : JMS 2003; 38:955-961. [PMID: 14505323 DOI: 10.1002/jms.509] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Nitrile hydratases (NHases) are industrially significant iron- and cobalt-containing enzymes used in the large-scale synthesis of acrylamide. Previous reports have shown that the active site peptides of NHases are post-translationally modified by oxidation of cysteine residues, and that these modifications are essential for catalysis. We report mass spectrometric evidence of the oxidation states of the active site cysteines in the iron coordination spheres of two iron-containing nitrile hydratases, namely R312 NHase from Rhodococcus rhodochrous strain R312 and NI1 NHase from Comamonas testosteroni. At least one of these cysteines is oxidised to a sulfinic acid (SO(2)H) and there is also evidence suggesting an additional oxidation to a sulfenic acid (SOH). This is the first evidence for the presence of these oxidation states for full-length NHases and for Fe-NHases from different microorganisms. The presence of these covalent modifications was confirmed by performing mass spectrometry on the active site peptide of R312 NHase, under native, reduced and carboxymethylated conditions. We also show the nitrosylation of the iron by mass spectrometry, as well as the release of NO by photoirradiation.
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Affiliation(s)
- Julie M Stevens
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques (UMR 8601 CNRS), Université René Descartes Paris V, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France
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74
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Stevens JM, Rao Saroja N, Jaouen M, Belghazi M, Schmitter JM, Mansuy D, Artaud I, Sari MA. Chaperone-assisted expression, purification, and characterization of recombinant nitrile hydratase NI1 from Comamonas testosteroni. Protein Expr Purif 2003; 29:70-6. [PMID: 12729727 DOI: 10.1016/s1046-5928(03)00008-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Nitrile hydratases (NHases) are industrially important iron- and cobalt-containing enzymes that are used in the large-scale synthesis of acrylamide. Heterologous expression of NHases has been complicated by the fact that other proteins (activators or metallochaperones) appear to be required to produce NHases in their catalytically active form. We report a novel heterologous system for the expression of catalytically active iron-containing NI1 NHase in Escherichia coli, involving coexpression with the E. coli GroES and GroEL chaperones. The purified recombinant enzyme was found to be highly similar to the enzyme purified from Comamonas testosteroni according to its spectroscopic features, catalytic properties with various substrates, and post-translational modifications. In addition, we report a rapid and convenient spectrophotometric method to monitor the activity of NI1 NHase during purification.
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Affiliation(s)
- Julie M Stevens
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques (UMR 8601 CNRS), Université Paris V, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France
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75
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Hashimoto Y, Sasaki S, Herai S, Oinuma KI, Shimizu S, Kobayashi M. Site-directed mutagenesis for cysteine residues of cobalt-containing nitrile hydratase. J Inorg Biochem 2002; 91:70-7. [PMID: 12121763 DOI: 10.1016/s0162-0134(02)00373-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Three cysteine residues, which are completely conserved among alpha-subunits in all nitrile hydratases, are thought to be the ligands of a metal ion in the catalytic center of this enzyme. These cysteine residues (i.e. alpha C102, alpha C105 and alpha C107) in the high-molecular-mass nitrile hydratase (H-NHase) of Rhodococcus rhodochrous J1 were replaced with alanine by site-directed mutagenesis using the R. rhodochrous ATCC12674 host-vector system, and the resultant transformants were investigated. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for the cell-free extracts of each mutant transformant revealed that four mutant transformants (i.e. alpha C105A, alpha C107A, alpha C102A/C105A and alpha C105A/C107A) showed predominant alpha- and beta-subunit protein bands with a mobility identical to those of the native H-NHase, while three mutant transformants (i.e. alpha C102A, alpha C102A/C107A and alpha C102A/C105A/C107A) did not produce the corresponding proteins. The purified former four mutant enzymes showed neither enzymatic activity nor the maximum absorption at 410 nm which was detected in the wild type H-NHase. They also did not contain cobalt ions. Based upon these findings, these three cysteine residues were found to be essential for the active expression of H-NHase.
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Affiliation(s)
- Yoshiteru Hashimoto
- Institute of Applied Biochemistry, The University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
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76
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Claiborne A, Mallett TC, Yeh JI, Luba J, Parsonage D. Structural, redox, and mechanistic parameters for cysteine-sulfenic acid function in catalysis and regulation. ADVANCES IN PROTEIN CHEMISTRY 2002; 58:215-76. [PMID: 11665489 DOI: 10.1016/s0065-3233(01)58006-7] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A primary objective of this review is to facilitate the application of the chemical and structural approaches that are currently being employed in the identification of Cys-SOH, as both transient intermediates and stable redox forms, in biochemical systems where these derivatives are suspected of playing key roles in redox catalysis or regulation. These range from high-resolution crystallographic analyses benefiting from recent technological advances in rapid data collection at cryogenic temperatures to 13C NMR investigations of [3-(13)C]Cys-labeled proteins and chemical modification protocols that can be integrated with both UV-visible and fluorescence spectroscopic as well as mass spectrometric (especially ESI, MALDI-TOF, and even FT ion-cyclotron-resonance) analyses. In summarizing the diversity of biological functions currently identified with Cys-SH reversible Cys-SOH redox cycles (Fig. 17), it should also be [figure: see text] emphasized that in at least one protein (nitrile hydratase) stable Cys-SOH and Cys-SO2H derivatives play important structural roles while also modulating the electronic properties of the iron center; in neither case is the Cys-SOH residue itself involved in reduction and oxidation. The somewhat incomplete structural descriptions of the oxidized Cys forms involved in redox regulation of some transcription factors (e.g., BPV-1 E2 protein and activator protein-1) indicate that there is ample room for the application of the types of investigations employed, for example, with NADH peroxidase and the AhpC peroxiredoxin, with a view toward defining the potential roles of Cys-SOH in these very important contexts of intracellular redox signaling. These advances will also build on the recent progress in defining sulfenic acid stabilization and properties in small molecule model systems, as evidenced in the work of Okazaki, Goto, and others. When viewed in the perspective of Allison's 1976 review on the subject of sulfenic acids in proteins, the reader will hopefully come to appreciate the conclusion that the concept of protein-sulfenic acids has now become a very well-defined and established principle of biochemistry, with current efforts in this and other laboratories being directed to bring about still more detailed understanding of Cys-SOH function in both redox and nonredox modes of enzyme catalysis and regulation of protein function.
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Affiliation(s)
- A Claiborne
- Department of Biochemistry, Wake Forest University Medical Center, Winston-Salem, North Carolina 27157, USA
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77
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Affiliation(s)
- J S Stamler
- Howard Hughes Medical Institute and Department of Medicine and Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
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78
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Wilcox DE, Schenk AD, Feldman BM, Xu Y. Oxidation of zinc-binding cysteine residues in transcription factor proteins. Antioxid Redox Signal 2001; 3:549-64. [PMID: 11554444 DOI: 10.1089/15230860152542925] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recent results on the oxidation of cysteine residues that bind zinc in transcription factors and their analogous peptides and in related proteins and model systems are reviewed. Two classes of oxidants, the transition metals and dioxygen, hydrogen peroxide, and related species, are considered, and the role of metal ions in suppressing or enhancing Cys oxidation is a major focus. Cysteines in the zinc-bound structures of transcription factors are less susceptible to oxidation than in the metal-free form, and this appears to correlate with reduced accessibility of the thiolates to oxidants. Substitution of other metal ions for Zn(II) increases the rate of Cys oxidation, apparently through increased oxidant accessibility. Reactions that result in reversible or irreversible oxidation of these zinc-binding cysteines under biological conditions are identified in the context of deleterious implications for gene expression.
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Affiliation(s)
- D E Wilcox
- Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA.
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79
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Jackson HL, Shoner SC, Rittenberg D, Cowen JA, Lovell S, Barnhart D, Kovacs JA. Probing the influence of local coordination environment on the properties of Fe-type nitrile hydratase model complexes. Inorg Chem 2001; 40:1646-53. [PMID: 11261975 PMCID: PMC4485621 DOI: 10.1021/ic001271d] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of four structurally related cis-dithiolate-ligated Fe(III) complexes, [Fe(III)(DITpy)2]Cl (1), [Fe(III)(DITIm)2]Cl (2), [Fe(III)(ADIT)2]Cl (3), and [Fe(III)(AMIT)2]Cl (4), are described. The structural characterization of 3 as well as the spectroscopic properties of 3 and 4 has been previously reported. Crystal data for 1, 2, and 4 are as follows: 1.3H2O crystallizes in the orthorhombic space group Pca2(1) with a = 19.800(4) A, b = 18.450(4) A, c = 14.800(3) A, and Z = 8. 2.(1/2)EtOH.1/2H2O crystallizes in the monoclinic space group Cc with a = 24.792(4) A, b = 14.364(3) A, c = 17.527(3) A, beta = 124.91(2) degrees, and Z = 8. 4 crystallizes in the triclinic space group P1 with a = 8.0152(6) A, b = 10.0221(8) A, c = 11.8384(10) A, alpha = 73.460(3) degrees, beta = 71.451(5) degrees, gamma = 72.856(4) degrees, and Z = 2. Complexes 1-4 share a common S2N4 coordination environment that consists of two cis-thiolates, two trans-imines, and two cis-terminal nitrogen donors: Nterm = pyridine (1), imidazole (2), and primary amine (3 and 4). The crystallographically determined mean Fe-S bond distances in 1-4 range from 2.196 to 2.232 A and are characteristic of low-spin Fe(III)-thiolate complexes. The low-spin S = 1/2 ground state was confirmed by both EPR and magnetic susceptibility measurements. The electronic spectra of these complexes are characterized by broad absorption bands centered near approximately 700 nm that are consistent with ligand-to-metal charge-transfer (CT) bands. The complexes were further characterized by cyclic voltammetry measurements, and all possess highly negative Fe(III)/Fe(II) redox couples ( approximately -1 V vs SCE, saturated calomel electrode) indicating that alkyl thiolate donors are effective at stabilizing Fe(III) centers. Both the redox couple and the 700 nm band in the visible spectra show solvent-dependent shifts that are dependent upon the H-bonding ability of the solvent. The implications of these results with respect to the active site of the iron-containing nitrile hydratases are also discussed.
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Affiliation(s)
| | | | | | | | | | | | - Julie A. Kovacs
- Author to whom correspondence should be addressed: Dr. Julie A. Kovacs, Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700. . Fax: 206-685-8665
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80
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Endo I, Nojiri M, Tsujimura M, Nakasako M, Nagashima S, Yohda M, Odaka M. Fe-type nitrile hydratase. J Inorg Biochem 2001; 83:247-53. [PMID: 11293544 DOI: 10.1016/s0162-0134(00)00171-9] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The characteristic features of Fe-type nitrile hydratase (NHase) from Rhodococcus sp. N-771 are described. Through the biochemical analyses, we have found that nitric oxide (NO) regulates the photoreactivity of this enzyme by association with the non-heme iron center and photoinduced dissociation from it. The regulation is realized by a unique structure of the catalytic non-heme iron center composed of post-translationally modified cysteine-sulfinic (Cys-SO2H) and -sulfenic acids (Cys-SOH). To understand the biogenic mechanism and the functional role of these modifications, we constructed an over-expression system of whole NHase and individual subunits in Escherichia coli. The results of the studies on several recombinant NHases have shown that the Cys-SO2H oxidation of alphaC112 is indispensable for the catalytic activity of Fe-type NHase.
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Affiliation(s)
- I Endo
- Biochemical Systems Laboratory, The Institute of Physical and Chemical Research (RIKEN), Wako-shi, Saitama, Japan.
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81
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Cloning and expression of the nitrile hydratase and amidase genes from Bacillus sp. BR449 into Escherichia coli. Enzyme Microb Technol 2000; 27:492-501. [PMID: 10978771 DOI: 10.1016/s0141-0229(00)00248-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A moderate thermophile, Bacillus sp. BR449 was previously shown to exhibit a high level of nitrile hydratase (NHase) activity when growing on high levels of acrylonitrile at 55 degrees C. In this report, we describe the cloning of a 6.1 kb SalI DNA fragment encoding the NHase gene cluster of BR449 into Escherichia coli. Nucleotide sequencing revealed six ORFs encoding (in order), two unidentified putative proteins, amidase, NHase beta- and alpha-subunits and a small putative protein of 101 amino acids designated P12K. Spacings and orientation of the coding regions as well as their gene expression in E. coli suggest that the beta-subunit, alpha-subunit, and P12K genes are co-transcribed. Analysis of deduced amino acid sequences indicate that the amidase (348 aa, MW 38.6 kDa) belongs to the nitrilase-related aliphatic amidase family, and that the NHase beta- (229 aa, MW 26.5 kDa) and alpha- (214 aa, MW 24.5 kDa) subunits comprise a cobalt-containing member of the NHase family, which includes Rhodococcus rhodochrous J1 and Pseudomonas putida 5B NHases. The amidase/NHase gene cluster differs both in arrangement and composition from those described for other NHase-producing strains. When expressed in Escherichia coli DH5alpha, the subcloned NHase genes produced significant levels of active NHase enzyme when cobalt ion was added either to the culture medium or cell extracts. Presence of the P12K gene and addition of amide compounds as inducers were not required for this expression.
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83
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Kung I, Schweitzer D, Shearer J, Taylor WD, Jackson HL, Lovell S, Kovacs JA. How Do Oxidized Thiolate Ligands Affect the Electronic and Reactivity Properties of a Nitrile Hydratase Model Compound? J Am Chem Soc 2000. [DOI: 10.1021/ja0017561] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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84
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Piersma SR, Nojiri M, Tsujimura M, Noguchi T, Odaka M, Yohda M, Inoue Y, Endo I. Arginine 56 mutation in the beta subunit of nitrile hydratase: importance of hydrogen bonding to the non-heme iron center. J Inorg Biochem 2000; 80:283-8. [PMID: 11001100 DOI: 10.1016/s0162-0134(00)00076-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Arginine 56 in the beta subunit (betaArg56) of the iron-containing nitrile hydratase (NHase), one of the strongly conserved residues within the NHase family, is known to form hydrogen bonds to the sulfinyl (-SO2H) and sulfenyl (-SOH) groups of the post-translationally modified cysteine residues in the catalytic center. BetaArg56 was substituted by tyrosine, glutamate or lysine, respectively, and the respective mutant enzymes generated by reconstitution were characterized. The betaR56K mutant complex exhibited about 1% of the enzymatic activity of native NHase, while the others were totally inactive. The kinetic analysis of the betaR56K mutant complex exhibited a drastic decrease in turnover number and decreases in kinetic constants for substrate and inhibitors as compared to the native NHase. Changes in UV-visible absorption and light-induced Fourier transform infrared difference spectra suggest that betaArg56 is involved in the positioning of the -SO2H and -SOH groups of the modified Cys residues in the catalytic center so as to fine tune the electronic state of the iron center suitable for catalysis. Thus, betaArg56 is essential for catalysis.
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Affiliation(s)
- S R Piersma
- Biochemical Systems Laboratory, RIKEN (The Institute of Physical and Chemical Research), Wako, Saitama, Japan
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85
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Murakami T, Nojiri M, Nakayama H, Odaka M, Yohda M, Dohmae N, Takio K, Nagamune T, Endo I. Post-translational modification is essential for catalytic activity of nitrile hydratase. Protein Sci 2000; 9:1024-30. [PMID: 10850812 PMCID: PMC2144646 DOI: 10.1110/ps.9.5.1024] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Nitrile hydratase from Rhodococcus sp. N-771 is an alphabeta heterodimer with a nonheme ferric iron in the catalytic center. In the catalytic center, alphaCys112 and alphaCys114 are modified to a cysteine sulfinic acid (Cys-SO2H) and a cysteine sulfenic acid (Cys-SOH), respectively. To understand the function and the biogenic mechanism of these modified residues, we reconstituted the nitrile hydratase from recombinant unmodified subunits. The alphabeta complex reconstituted under argon exhibited no activity. However, it gradually gained the enzymatic activity through aerobic incubation. ESI-LC/MS analysis showed that the anaerobically reconstituted alphabeta complex did not have the modification of alphaCys112-SO2H and aerobic incubation induced the modification. The activity of the reconstituted alphabeta complex correlated with the amount of alphaCys112-SO2H. Furthermore, ESI-LC/MS analyses of the tryptic digest of the reconstituted complex, removed of ferric iron at low pH and carboxamidomethylated without reduction, suggested that alphaCys114 is modified to Cys-SOH together with the sulfinic acid modification of alphaCys112. These results suggest that alphaCys112 and alphaCys114 are spontaneously oxidized to Cys-SO2H and Cys-SOH, respectively, and alphaCys112-SO2H is responsible for the catalytic activity solely or in combination with alphaCys114-SOH.
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Affiliation(s)
- T Murakami
- RIKEN (The Institute of Physical and Chemical Research), Wako, Saitama, Japan
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86
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Nojiri M, Nakayama H, Odaka M, Yohda M, Takio K, Endo I. Cobalt-substituted Fe-type nitrile hydratase of Rhodococcus sp. N-771. FEBS Lett 2000; 465:173-7. [PMID: 10631329 DOI: 10.1016/s0014-5793(99)01746-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
When the genes encoding alpha and beta subunits of Fe-type nitrile hydratase (NHase) from Rhodococcus sp. N-771 were expressed in Escherichia coli in Co-supplemented medium without co-expression of the NHase activator, the NHase specifically incorporated not Fe but Co ion into the catalytic center. The produced Co-substituted enzyme exhibited rather weak NHase activity, initially. However, the activity gradually increased by the incubation with an oxidizing agent, potassium hexacyanoferrate. The oxidizing agent is likely to activate the Co-substituent by oxidizing the Co atom to a low-spin Co(3+) state and/or modification of alphaCys-112 to a cysteine-sulfinic acid. It is suggested that the NHase activator not only supports the insertion of an Fe ion into the NHase protein but also activates the enzyme via the oxidation of its iron center.
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Affiliation(s)
- M Nojiri
- Biochemical Systems Laboratory, RIKEN (The Institute of Physical and Chemical Research), Hirosawa 2-1, Wako, Saitama, Japan
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Claiborne A, Yeh JI, Mallett TC, Luba J, Crane EJ, Charrier V, Parsonage D. Protein-sulfenic acids: diverse roles for an unlikely player in enzyme catalysis and redox regulation. Biochemistry 1999; 38:15407-16. [PMID: 10569923 DOI: 10.1021/bi992025k] [Citation(s) in RCA: 403] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
While it has been known for more than 20 years that unusually stable cysteine-sulfenic acid (Cys-SOH) derivatives can be introduced in selected proteins by mild oxidation, only recently have chemical and crystallographic evidence for functional Cys-SOH been presented with native proteins such as NADH peroxidase and NADH oxidase, nitrile hydratase, and the hORF6 and AhpC peroxiredoxins. In addition, Cys-SOH forms of protein tyrosine phosphatases and glutathione reductase have been suggested to play key roles in the reversible inhibition of these enzymes during tyrosine phosphorylation-dependent signal transduction events and nitrosative stress, respectively. Substantial chemical data have also been presented which implicate Cys-SOH in redox regulation of transcription factors such as Fos and Jun (activator protein-1) and bovine papillomavirus-1 E2 protein. Functionally, the Cys-SOHs in NADH peroxidase, NADH oxidase, and the peroxiredoxins serve as either catalytically essential redox centers or transient intermediates during peroxide reduction. In nitrile hydratase, the active-site Cys-SOH functions in both iron coordination and NO binding but does not play any catalytic redox role. In Fos and Jun and the E2 protein, on the other hand, a key Cys-SH serves as a sensor for intracellular redox status; reversible oxidation to Cys-SOH as proposed inhibits the corresponding DNA binding activity. These functional Cys-SOHs have roles in diverse cellular processes, including signal transduction, oxygen metabolism and the oxidative stress response, and transcriptional regulation, as well as in the industrial production of acrylamide, and their detailed analyses are beginning to provide the chemical foundation necessary for understanding protein-SOH stabilization and function.
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Affiliation(s)
- A Claiborne
- Department of Biochemistry, Wake Forest University Medical Center, Winston-Salem, North Carolina 27157, USA
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