1
|
Garber AI, Nealson KH, Okamoto A, McAllister SM, Chan CS, Barco RA, Merino N. FeGenie: A Comprehensive Tool for the Identification of Iron Genes and Iron Gene Neighborhoods in Genome and Metagenome Assemblies. Front Microbiol 2020; 11:37. [PMID: 32082281 PMCID: PMC7005843 DOI: 10.3389/fmicb.2020.00037] [Citation(s) in RCA: 158] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 01/09/2020] [Indexed: 01/15/2023] Open
Abstract
Iron is a micronutrient for nearly all life on Earth. It can be used as an electron donor and electron acceptor by iron-oxidizing and iron-reducing microorganisms and is used in a variety of biological processes, including photosynthesis and respiration. While it is the fourth most abundant metal in the Earth's crust, iron is often limiting for growth in oxic environments because it is readily oxidized and precipitated. Much of our understanding of how microorganisms compete for and utilize iron is based on laboratory experiments. However, the advent of next-generation sequencing and surge in publicly available sequence data has made it possible to probe the structure and function of microbial communities in the environment. To bridge the gap between our understanding of iron acquisition, iron redox cycling, iron storage, and magnetosome formation in model microorganisms and the plethora of sequence data available from environmental studies, we have created a comprehensive database of hidden Markov models (HMMs) based on genes related to iron acquisition, storage, and reduction/oxidation in Bacteria and Archaea. Along with this database, we present FeGenie, a bioinformatics tool that accepts genome and metagenome assemblies as input and uses our comprehensive HMM database to annotate provided datasets with respect to iron-related genes and gene neighborhood. An important contribution of this tool is the efficient identification of genes involved in iron oxidation and dissimilatory iron reduction, which have been largely overlooked by standard annotation pipelines. We validated FeGenie against a selected set of 28 isolate genomes and showcase its utility in exploring iron genes present in 27 metagenomes, 4 isolate genomes from human oral biofilms, and 17 genomes from candidate organisms, including members of the candidate phyla radiation. We show that FeGenie accurately identifies iron genes in isolates. Furthermore, analysis of metagenomes using FeGenie demonstrates that the iron gene repertoire and abundance of each environment is correlated with iron richness. While this tool will not replace the reliability of culture-dependent analyses of microbial physiology, it provides reliable predictions derived from the most up-to-date genetic markers. FeGenie's database will be maintained and continually updated as new genes are discovered. FeGenie is freely available: https://github.com/Arkadiy-Garber/FeGenie.
Collapse
Affiliation(s)
- Arkadiy I. Garber
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States
- Department of Earth Sciences, University of Delaware, Newark, DE, United States
| | - Kenneth H. Nealson
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States
| | - Akihiro Okamoto
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Sean M. McAllister
- School of Marine Science and Policy, University of Delaware, Newark, DE, United States
| | - Clara S. Chan
- Department of Earth Sciences, University of Delaware, Newark, DE, United States
- School of Marine Science and Policy, University of Delaware, Newark, DE, United States
| | - Roman A. Barco
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States
| | - Nancy Merino
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA, United States
| |
Collapse
|
2
|
Uchida T, Dojun N, Ota K, Sekine Y, Nakamura Y, Umetsu S, Ishimori K. Role of conserved arginine in the heme distal site of HutZ from Vibrio cholerae in the heme degradation reaction. Arch Biochem Biophys 2019; 677:108165. [PMID: 31689379 DOI: 10.1016/j.abb.2019.108165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 10/25/2019] [Accepted: 10/30/2019] [Indexed: 10/25/2022]
Abstract
HutZ from Vibrio cholerae is a dimeric enzyme that catalyzes degradation of heme. The highly conserved Arg92 residue in the HutZ family is proposed to interact with an iron-bound water molecule in the distal heme pocket. To clarify the specific role of Arg92 in the heme degradation reaction, the residue was substituted with alanine, leucine, histidine or lysine to modulate electrostatic interactions with iron-bound ligand. All four Arg92 mutants reacted with hydrogen peroxide to form verdoheme, a prominent intermediate in the heme degradation process. However, when ascorbic acid was used as an electron source, iron was not released even at pH 6.0 despite a decrease in the Soret band, indicating that non-enzymatic heme degradation occurred. Comparison of the rates of heme reduction, ligand binding and verdoheme formation suggested that proton transfer to the reduced oxyferrous heme, a potential rate-limiting step of heme degradation in HutZ, is hampered by mutation. In our previous study, we found that the increase in the distance between heme and Trp109 from 16 to 18 Å upon lowering the pH from 8.0 to 6.0 leads to activation of ascorbic acid-assisted heme degradation by HutZ. The distance in Arg92 mutants was >19 Å at pH 6.0, suggesting that subunit-subunit interactions at this pH are not suitable for heme degradation, similar to Asp132 and His63 mutants. These results suggest that interactions of Arg92 with heme-bound ligand induce alterations in the distance between subunits, which plays a key role in controlling the heme degradation activity of HutZ.
Collapse
Affiliation(s)
- Takeshi Uchida
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan; Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, 060-8628, Japan.
| | - Nobuhiko Dojun
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Kazuki Ota
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Yukari Sekine
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Yuina Nakamura
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Sayaka Umetsu
- Division of Chemistry, School of Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Koichiro Ishimori
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan; Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, 060-8628, Japan
| |
Collapse
|
3
|
Adam SM, Wijeratne GB, Rogler PJ, Diaz DE, Quist DA, Liu JJ, Karlin KD. Synthetic Fe/Cu Complexes: Toward Understanding Heme-Copper Oxidase Structure and Function. Chem Rev 2018; 118:10840-11022. [PMID: 30372042 PMCID: PMC6360144 DOI: 10.1021/acs.chemrev.8b00074] [Citation(s) in RCA: 132] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Heme-copper oxidases (HCOs) are terminal enzymes on the mitochondrial or bacterial respiratory electron transport chain, which utilize a unique heterobinuclear active site to catalyze the 4H+/4e- reduction of dioxygen to water. This process involves a proton-coupled electron transfer (PCET) from a tyrosine (phenolic) residue and additional redox events coupled to transmembrane proton pumping and ATP synthesis. Given that HCOs are large, complex, membrane-bound enzymes, bioinspired synthetic model chemistry is a promising approach to better understand heme-Cu-mediated dioxygen reduction, including the details of proton and electron movements. This review encompasses important aspects of heme-O2 and copper-O2 (bio)chemistries as they relate to the design and interpretation of small molecule model systems and provides perspectives from fundamental coordination chemistry, which can be applied to the understanding of HCO activity. We focus on recent advancements from studies of heme-Cu models, evaluating experimental and computational results, which highlight important fundamental structure-function relationships. Finally, we provide an outlook for future potential contributions from synthetic inorganic chemistry and discuss their implications with relevance to biological O2-reduction.
Collapse
Affiliation(s)
- Suzanne M. Adam
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Gayan B. Wijeratne
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Patrick J. Rogler
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Daniel E. Diaz
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - David A. Quist
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Jeffrey J. Liu
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kenneth D. Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| |
Collapse
|
4
|
Matsui T, Sugiyama R, Sakanashi K, Tamura Y, Iida M, Nambu Y, Higuchi T, Suematsu M, Ikeda-Saito M. Hydrogen sulfide bypasses the rate-limiting oxygen activation of heme oxygenase. J Biol Chem 2018; 293:16931-16939. [PMID: 30237172 DOI: 10.1074/jbc.ra118.004641] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 08/29/2018] [Indexed: 12/31/2022] Open
Abstract
Discovery of unidentified protein functions is of biological importance because it often provides new paradigms for many research areas. Mammalian heme oxygenase (HO) enzyme catalyzes the O2-dependent degradation of heme into carbon monoxide (CO), iron, and biliverdin through numerous reaction intermediates. Here, we report that H2S, a gaseous signaling molecule, is part of a novel reaction pathway that drastically alters HO's products, reaction mechanism, and catalytic properties. Our prediction of this interplay is based on the unique reactivity of H2S with one of the HO intermediates. We found that in the presence of H2S, HO produces new linear tetrapyrroles, which we identified as isomers of sulfur-containing biliverdin (SBV), and that only H2S, but not GSH, cysteine, and polysulfides, induces SBV formation. As BV is converted to bilirubin (BR), SBV is enzymatically reduced to sulfur-containing bilirubin (SBR), which shares similar properties such as antioxidative effects with normal BR. SBR was detected in culture media of mouse macrophages, confirming the existence of this H2S-induced reaction in mammalian cells. H2S reacted specifically with a ferric verdoheme intermediate of HO, and verdoheme cleavage proceeded through an O2-independent hydrolysis-like mechanism. This change in activation mode diminished O2 dependence of the overall HO activity, circumventing the rate-limiting O2 activation of HO. We propose that H2S could largely affect O2 sensing by mammalian HO, which is supposed to relay hypoxic signals by decreasing CO output to regulate cellular functions. Moreover, the novel H2S-induced reaction identified here helps sustain HO's heme-degrading and antioxidant-generating capacity under highly hypoxic conditions.
Collapse
Affiliation(s)
- Toshitaka Matsui
- From the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan,
| | - Ryota Sugiyama
- From the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan
| | - Kenta Sakanashi
- From the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan
| | - Yoko Tamura
- From the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan
| | - Masaki Iida
- From the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan
| | - Yukari Nambu
- From the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan
| | - Tsunehiko Higuchi
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Tanabe-dori, Mizuho, Nagoya 467-8603, Japan, and
| | - Makoto Suematsu
- Department of Biochemistry, Keio University School of Medicine, Shinano-machi, Shinjyuku, Tokyo 160-8582, Japan
| | - Masao Ikeda-Saito
- From the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan,
| |
Collapse
|
5
|
The Asp99-Arg188 salt bridge of the Pseudomonas aeruginosa HemO is critical in allowing conformational flexibility during catalysis. J Biol Inorg Chem 2018; 23:1057-1070. [PMID: 30194537 DOI: 10.1007/s00775-018-1609-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 08/23/2018] [Indexed: 12/17/2022]
Abstract
The P. aeruginosa iron-regulated heme oxygenase (HemO) is required within the host for the utilization of heme as an iron source. As iron is essential for survival and virulence, HemO represents a novel antimicrobial target. We recently characterized small molecule inhibitors that bind to an allosteric site distant from the heme pocket, and further proposed binding at this site disrupts a nearby salt bridge between D99 and R188. Herein, through a combination of site-directed mutagenesis and hydrogen-deuterium exchange mass spectrometry (HDX-MS), we determined that the disruption of the D99-R188 salt bridge leads to significant decrease in conformational flexibility within the distal and proximal helices that form the heme-binding site. The RR spectra of the resting state Fe(III) and reduced Fe(II)-deoxy heme-HemO D99A, R188A and D99/R188A complexes are virtually identical to those of wild-type HemO, indicating no significant change in the heme environment. Furthermore, mutation of D99 or R188 leads to a modest decrease in the stability of the Fe(II)-O2 heme complex. Despite this slight difference in Fe(II)-O2 stability, we observe complete loss of enzymatic activity. We conclude the loss of activity is a result of decreased conformational flexibility in helices previously shown to be critical in accommodating variation in the distal ligand and the resulting chemical intermediates generated during catalysis. Furthermore, this newly identified allosteric binding site on HemO represents a novel alternative drug-design strategy to that of competitive inhibition at the active site or via direct coordination of ligands to the heme iron.
Collapse
|
6
|
Uchida T, Sekine Y, Dojun N, Lewis-Ballester A, Ishigami I, Matsui T, Yeh SR, Ishimori K. Reaction intermediates in the heme degradation reaction by HutZ from Vibrio cholerae. Dalton Trans 2018; 46:8104-8109. [PMID: 28607990 DOI: 10.1039/c7dt01562c] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
HutZ is a heme-degrading enzyme in Vibrio cholerae. It converts heme to biliverdin via verdoheme, suggesting that it follows the same reaction mechanism as that of mammalian heme oxygenase. However, none of the key intermediates have been identified. In this study, we applied steady-state and time-resolved UV-vis absorption and resonance Raman spectroscopy to study the reaction of the heme-HutZ complex with H2O2 or ascorbic acid. We characterized three intermediates: oxyferrous heme, meso-hydroxyheme, and verdoheme complexes. Our data support the view that HutZ degrades heme in a manner similar to mammalian heme oxygenase, despite their low sequence and structural homology.
Collapse
Affiliation(s)
- Takeshi Uchida
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
7
|
Alavi FS, Gheidi M, Zahedi M, Safari N, Ryde U. A novel mechanism of heme degradation to biliverdin studied by QM/MM and QM calculations. Dalton Trans 2018; 47:8283-8291. [DOI: 10.1039/c8dt00064f] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Heme degradation by heme oxygenase enzymes is important for maintaining iron homeostasis and prevention of oxidative stress.
Collapse
Affiliation(s)
- Fatemeh Sadat Alavi
- Department of Chemistry
- Faculty of Sciences
- Shahid Beheshti University
- Tehran
- Iran
| | - Mahin Gheidi
- Department of Chemistry
- Faculty of Sciences
- Shahid Beheshti University
- Tehran
- Iran
| | - Mansour Zahedi
- Department of Chemistry
- Faculty of Sciences
- Shahid Beheshti University
- Tehran
- Iran
| | - Nasser Safari
- Department of Chemistry
- Faculty of Sciences
- Shahid Beheshti University
- Tehran
- Iran
| | - Ulf Ryde
- Department of Theoretical Chemistry
- Lund University
- Chemical Centre
- SE-221 00 Lund
- Sweden
| |
Collapse
|
8
|
Carels N, Gumiel M, da Mota FF, de Carvalho Moreira CJ, Azambuja P. A Metagenomic Analysis of Bacterial Microbiota in the Digestive Tract of Triatomines. Bioinform Biol Insights 2017; 11:1177932217733422. [PMID: 28989277 PMCID: PMC5624349 DOI: 10.1177/1177932217733422] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 04/10/2017] [Indexed: 12/04/2022] Open
Abstract
The digestive tract of triatomines (DTT) is an ecological niche favored by microbiota whose enzymatic profile is adapted to the specific substrate availability in this medium. This report describes the molecular enzymatic properties that promote bacterial prominence in the DTT. The microbiota composition was assessed previously based on 16S ribosomal DNA, and whole sequenced genomes of bacteria from the same genera were used to calculate the GC level of rare and prominent bacterial species in the DTT. The enzymatic reactions encoded by coding sequences of both rare and common bacterial species were then compared and revealed key functions explaining why some genera outcompete others in the DTT. Representativeness of DTT microbiota was investigated by shotgun sequencing of DNA extracted from bacteria grown in liquid Luria-Bertani broth (LB) medium. Results showed that GC-rich bacteria outcompete GC-poor bacteria and are the dominant components of the DTT microbiota. In addition, oxidoreductases are the main enzymatic components of these bacteria. In particular, nitrate reductases (anaerobic respiration), oxygenases (catabolism of complex substrates), acetate-CoA ligase (tricarboxylic acid cycle and energy metabolism), and kinase (signaling pathway) were the major enzymatic determinants present together with a large group of minor enzymes including hydrogenases involved in energy and amino acid metabolism. In conclusion, despite their slower growth in liquid LB medium, bacteria from GC-rich genera outcompete the GC-poor bacteria because their specific enzymatic abilities impart a selective advantage in the DTT.
Collapse
Affiliation(s)
- Nicolas Carels
- Laboratório de Modelagem de Sistemas Biológicos, National Institute for Science and Technology on Innovation in Neglected Diseases (INCT-IDN), Centro de Desenvolvimento Tecnológico em Saúde (CDTS), Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
| | - Marcial Gumiel
- Laboratório de Bioquímica e Fisiologia de Insetos, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (IOC/FIOCRUZ), Rio de Janeiro, Brazil
| | - Fabio Faria da Mota
- Laboratório de Biologia Computacional e Sistemas, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (IOC/FIOCRUZ), Rio de Janeiro, Brazil
| | | | - Patricia Azambuja
- Laboratório de Bioquímica e Fisiologia de Insetos, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (IOC/FIOCRUZ), Rio de Janeiro, Brazil.,Departamento de Entomologia Molecular, Instituto Nacional de Entomologia Molecular (INCT-EM), Rio de Janeiro, Brazil
| |
Collapse
|
9
|
Lee MJY, Wang Y, Jiang Y, Li X, Ma J, Tan H, Turner-Wood K, Rahman MN, Chen G, Jia Z. Function Coupling Mechanism of PhuS and HemO in Heme Degradation. Sci Rep 2017; 7:11273. [PMID: 28900278 PMCID: PMC5596023 DOI: 10.1038/s41598-017-11907-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 08/31/2017] [Indexed: 12/24/2022] Open
Abstract
Most bacteria possess only one heme-degrading enzyme for obtaining iron, however few bacteria such as Pseudomonas aeruginosa express two, namely PhuS and HemO. While HemO is a well-known heme oxygenase, previously we discovered that PhuS also possesses heme degradation activity and generates verdoheme, an intermediate of heme breakdown. To understand the coexistence of these two enzymes, using the DFT calculation we reveal that PhuS effectively enhances heme degradation through its participation in heme hydroxylation, the rate limiting reaction. Heme is converted to verdoheme in this reaction and the energy barrier for PhuS is substantially lower than for HemO. Thus, HemO is mainly involved in the ring opening reaction which converts verdoheme to biliverdin and free iron. Our kinetics experiments show that, in the presence of both PhuS and HemO, complete degradation of heme to biliverdin is enhanced. We further show that PhuS is more active than HemO using heme as a substrate and generates more CO. Combined experimental and theoretical results directly identify function coupling of this two-enzyme system, resulting in more efficient heme breakdown and utilization.
Collapse
Affiliation(s)
- Michael J Y Lee
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Ye Wang
- College of Chemistry, Beijing Normal University, 100875, Beijing, China
| | - Yafei Jiang
- College of Chemistry, Beijing Normal University, 100875, Beijing, China
| | - Xichen Li
- College of Chemistry, Beijing Normal University, 100875, Beijing, China
| | - Jianqiu Ma
- College of Chemistry, Beijing Normal University, 100875, Beijing, China
| | - Hongwei Tan
- College of Chemistry, Beijing Normal University, 100875, Beijing, China.
| | - Keegan Turner-Wood
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Mona N Rahman
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Guangju Chen
- College of Chemistry, Beijing Normal University, 100875, Beijing, China
| | - Zongchao Jia
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada. .,College of Chemistry, Beijing Normal University, 100875, Beijing, China.
| |
Collapse
|
10
|
Unique coupling of mono- and dioxygenase chemistries in a single active site promotes heme degradation. Proc Natl Acad Sci U S A 2016; 113:3779-84. [PMID: 27006503 DOI: 10.1073/pnas.1523333113] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bacterial pathogens must acquire host iron for survival and colonization. Because free iron is restricted in the host, numerous pathogens have evolved to overcome this limitation by using a family of monooxygenases that mediate the oxidative cleavage of heme into biliverdin, carbon monoxide, and iron. However, the etiological agent of tuberculosis, Mycobacterium tuberculosis, accomplishes this task without generating carbon monoxide, which potentially induces its latent state. Here we show that this unusual heme degradation reaction proceeds through sequential mono- and dioxygenation events within the single active center of MhuD, a mechanism unparalleled in enzyme catalysis. A key intermediate of the MhuD reaction is found to be meso-hydroxyheme, which reacts with O2 at an unusual position to completely suppress its monooxygenation but to allow ring cleavage through dioxygenation. This mechanistic change, possibly due to heavy steric deformation of hydroxyheme, rationally explains the unique heme catabolites of MhuD. Coexistence of mechanistically distinct functions is a previously unidentified strategy to expand the physiological outcome of enzymes, and may be applied to engineer unique biocatalysts.
Collapse
|
11
|
Osipovitch M, Lambrecht M, Baker C, Madha S, Mills JL, Craig PA, Bernstein HJ. Automated protein motif generation in the structure-based protein function prediction tool ProMOL. JOURNAL OF STRUCTURAL AND FUNCTIONAL GENOMICS 2015; 16:101-11. [PMID: 26573864 PMCID: PMC4684744 DOI: 10.1007/s10969-015-9199-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 10/30/2015] [Indexed: 11/28/2022]
Abstract
ProMOL, a plugin for the PyMOL molecular graphics system, is a structure-based protein function prediction tool. ProMOL includes a set of routines for building motif templates that are used for screening query structures for enzyme active sites. Previously, each motif template was generated manually and required supervision in the optimization of parameters for sensitivity and selectivity. We developed an algorithm and workflow for the automation of motif building and testing routines in ProMOL. The algorithm uses a set of empirically derived parameters for optimization and requires little user intervention. The automated motif generation algorithm was first tested in a performance comparison with a set of manually generated motifs based on identical active sites from the same 112 PDB entries. The two sets of motifs were equally effective in identifying alignments with homologs and in rejecting alignments with unrelated structures. A second set of 296 active site motifs were generated automatically, based on Catalytic Site Atlas entries with literature citations, as an expansion of the library of existing manually generated motif templates. The new motif templates exhibited comparable performance to the existing ones in terms of hit rates against native structures, homologs with the same EC and Pfam designations, and randomly selected unrelated structures with a different EC designation at the first EC digit, as well as in terms of RMSD values obtained from local structural alignments of motifs and query structures. This research is supported by NIH grant GM078077.
Collapse
Affiliation(s)
- Mikhail Osipovitch
- Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, NY, USA
| | - Mitchell Lambrecht
- School of Chemistry and Materials Science, Rochester Institute of Technology, Rochester, NY, USA
| | - Cameron Baker
- Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, NY, USA
| | - Shariq Madha
- Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, NY, USA
| | - Jeffrey L Mills
- School of Chemistry and Materials Science, Rochester Institute of Technology, Rochester, NY, USA
| | - Paul A Craig
- School of Chemistry and Materials Science, Rochester Institute of Technology, Rochester, NY, USA.
| | - Herbert J Bernstein
- School of Chemistry and Materials Science, Rochester Institute of Technology, Rochester, NY, USA
| |
Collapse
|
12
|
Dietl A, Maalcke W, Barends TRM. An unexpected reactivity of the P460cofactor in hydroxylamine oxidoreductase. ACTA ACUST UNITED AC 2015; 71:1708-13. [DOI: 10.1107/s1399004715010706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 06/03/2015] [Indexed: 11/11/2022]
Abstract
Hydroxylamine oxidoreductases (HAOs) contain a unique haem cofactor called P460that consists of a profoundly ruffledc-type haem with two covalent bonds between the haem porphyrin and a conserved tyrosine. This cofactor is exceptional in that it abstracts electrons from a ligand bound to the haem iron, whereas other haems involved in redox chemistry usually inject electrons into their ligands. The effects of the tyrosine cross-links and of the haem ruffling on the chemistry of this cofactor have been investigated theoretically but are not yet clear. A new crystal structure of an HAO fromCandidatusKuenenia stuttgartiensis, a model organism for anaerobic ammonium oxidation, now shows that its P460cofactor has yet another unexpected reactivity: when ethylene glycol was used as a cryoprotectant, the 1.8 Å resolution electron-density maps showed additional density which could be interpreted as an ethylene glycol molecule covalently bound to the C16atom of the haem ring, opposite the covalent links to the conserved tyrosine. Possible causes for this unexpected reactivity are discussed.
Collapse
|
13
|
Takayama SIJ, Loutet SA, Mauk AG, Murphy MEP. A Ferric-Peroxo Intermediate in the Oxidation of Heme by IsdI. Biochemistry 2015; 54:2613-21. [PMID: 25853501 DOI: 10.1021/acs.biochem.5b00239] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The canonical heme oxygenases (HOs) catalyze heme oxidation via a heme-bound hydroperoxo intermediate that is stabilized by a water cluster at the active site of the enzyme. In contrast, the hydrophobic active site of IsdI, a heme-degrading enzyme from Staphylococcus aureus, lacks a water cluster and is expected to oxidize heme by an alternative mechanism. Reaction of the IsdI-heme complex with either H2O2 or m-chloroperoxybenzoic acid fails to produce a specific oxidized heme iron intermediate, suggesting that ferric-hydroperoxo or ferryl derivatives of IsdI are not involved in the catalytic mechanism of this enzyme. IsdI lacks a proton-donating group in the distal heme pocket, so the possible involvement of a ferric-peroxo intermediate has been evaluated. Density functional theory (DFT) calculations indicate that heme oxidation involving a ferric-peroxo intermediate is energetically accessible, whereas the energy barrier for a reaction involving a ferric-hydroperoxo intermediate is too great in the absence of a proton donor. We propose that IsdI catalyzes heme oxidation through nucleophilic attack by the heme-bound peroxo species. This proposal is consistent with our previous demonstration by nuclear magnetic resonance spectroscopy that heme ruffling increases the susceptibility of the meso-carbon of heme to nucleophilic attack.
Collapse
Affiliation(s)
- Shin-Ichi J Takayama
- †Department of Microbiology and Immunology, ‡Department of Biochemistry and Molecular Biology, and §UBC Centre for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Slade A Loutet
- †Department of Microbiology and Immunology, ‡Department of Biochemistry and Molecular Biology, and §UBC Centre for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - A Grant Mauk
- †Department of Microbiology and Immunology, ‡Department of Biochemistry and Molecular Biology, and §UBC Centre for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Michael E P Murphy
- †Department of Microbiology and Immunology, ‡Department of Biochemistry and Molecular Biology, and §UBC Centre for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| |
Collapse
|
14
|
Wilks A, Ikeda-Saito M. Heme utilization by pathogenic bacteria: not all pathways lead to biliverdin. Acc Chem Res 2014; 47:2291-8. [PMID: 24873177 PMCID: PMC4139177 DOI: 10.1021/ar500028n] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
The eukaryotic heme oxygenases (HOs) (E.C. 1.14.99.3) convert heme
to biliverdin, iron, and carbon monoxide (CO) in three successive
oxygenation steps. Pathogenic bacteria require iron for survival and
infection. Extracellular heme uptake from the host plays a critical
role in iron acquisition and virulence. In the past decade, several
HOs required for the release of iron from extracellular heme have
been identified in pathogenic bacteria, including Corynebacterium
diphtheriae, Neisseriae meningitides, and Pseudomonas aeruginosa. The
bacterial enzymes were shown to be structurally and mechanistically
similar to those of the canonical eukaryotic HO enzymes. However,
the recent discovery of the structurally and mechanistically distinct
noncanonical heme oxygenases of Staphylococcus aureus and Mycobacterium tuberculosis has
expanded the reaction manifold of heme degradation. The distinct ferredoxin-like
structural fold and extreme heme ruffling are proposed to give rise
to the alternate heme degradation products in the S.
aureus and M. tuberculosis enzymes. In addition, several “heme-degrading factors”
with no structural homology to either class of HOs have recently been
reported. The identification of these “heme-degrading proteins”
has largely been determined on the basis of in vitro heme degradation
assays. Many of these proteins were reported to produce biliverdin,
although no extensive characterization of the products was performed.
Prior to the characterization of the canonical HO enzymes, the nonenzymatic
degradation of heme and heme proteins in the presence of a reductant
such as ascorbate or hydrazine, a reaction termed “coupled
oxidation”, served as a model for biological heme degradation.
However, it was recognized that there were important mechanistic differences
between the so-called coupled oxidation of heme proteins and enzymatic
heme oxygenation. In the coupled oxidation reaction, the final product,
verdoheme, can readily be converted to biliverdin under hydrolytic
conditions. The differences between heme oxygenation by the canonical
and noncanonical HOs and coupled oxidation will be discussed in the
context of the stabilization of the reactive FeIII–OOH
intermediate and regioselective heme hydroxylation. Thus, in the determination
of heme oxygenase activity in vitro, it is important to ensure that
the reaction proceeds through successive oxygenation steps. We further
suggest that when bacterial heme degradation is being characterized,
a systems biology approach combining genetics, mechanistic enzymology,
and metabolite profiling should be undertaken.
Collapse
Affiliation(s)
- Angela Wilks
- Department
of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201-1140, United States
| | - Masao Ikeda-Saito
- Institute
of Multidisciplinary Research for Advanced Materials, Tohoku University Katahira, Aoba, Sendai 980-8577, Japan
| |
Collapse
|
15
|
Tyrosine oxidation in heme oxygenase: examination of long-range proton-coupled electron transfer. J Biol Inorg Chem 2014; 19:1137-48. [PMID: 25023856 DOI: 10.1007/s00775-014-1169-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 06/05/2014] [Indexed: 01/01/2023]
Abstract
Heme oxygenase is responsible for the degradation of a histidine-ligated ferric protoporphyrin IX (Por) to biliverdin, CO, and the free ferrous ion. Described here are studies of tyrosyl radical formation reactions that occur after oxidizing Fe(III)(Por) to Fe(IV)=O(Por(·+)) in human heme oxygenase isoform-1 (hHO-1) and the structurally homologous protein from Corynebacterium diphtheriae (cdHO). Site-directed mutagenesis on hHO-1 probes the reduction of Fe(IV)=O(Por(·+)) by tyrosine residues within 11 Å of the prosthetic group. In hHO-1, Y58· is implicated as the most likely site of oxidation, based on the pH and pD dependent kinetics. The absence of solvent deuterium isotope effects in basic solutions of hHO-1 and cdHO contrasts with the behavior of these proteins in the acidic solution, suggesting that long-range proton-coupled electron transfer predominates over electron transfer.
Collapse
|
16
|
Oba T, Tateno Y, Ihara M, Fukusumi T, Takei N, Ito S. Radical reaction of chlorophyll derivatives triggered by AIBN. Tetrahedron Lett 2014. [DOI: 10.1016/j.tetlet.2013.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
17
|
Wilks A, Heinzl G. Heme oxygenation and the widening paradigm of heme degradation. Arch Biochem Biophys 2013; 544:87-95. [PMID: 24161941 DOI: 10.1016/j.abb.2013.10.013] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 10/09/2013] [Accepted: 10/15/2013] [Indexed: 12/11/2022]
Abstract
Heme degradation through the action of heme oxygenase (HO) is unusual in that it utilizes heme as both a substrate and cofactor for its own degradation. HO catalyzes the oxygen-dependent degradation of heme to biliverdin with the release of CO and "free" iron. The characterization of HO enzymes from humans to bacteria reveals a similar overall structural fold that contributes to the unique reaction manifold. The heme oxygenases share a similar heme-dependent activation of O2 to the ferric hydroperoxide as that of the cytochrome P450s and peroxidases. However, whereas the P450s promote cleavage of the ferric hydroperoxide OO bond to the oxoferryl species the HOs stabilize the ferric hydroperoxide promoting hydroxylation at the heme edge. The alternate reaction pathway in HO is achieved through the conformational flexibility and extensive hydrogen bond network within the heme binding site priming the heme for hydroxylation. Until recently it was believed that all heme degrading enzymes converted heme to biliverdin and iron, with the release of carbon monoxide (CO). However, the recent discovery of the bacterial IsdG-like heme degrading proteins of Staphylococcus aureus, Bacillus anthracis and Mycobacterium tuberculosis has expanded the reaction manifold of heme oxidation. Characterization of the heme degradation products in the IsdG-like reaction suggests a mechanism distinct from the classical HOs. In the following review we will discuss the structure-function of the canonical HOs as it relates to the emerging alternate reaction manifold of the IsdG-like proteins.
Collapse
Affiliation(s)
- Angela Wilks
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, MD 21201-1180, USA.
| | - Geoffrey Heinzl
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, MD 21201-1180, USA
| |
Collapse
|
18
|
Yamanishi K, Yairi T, Suzuki K, Kondo M. Biomimic O2 activation hydroxylates a meso-carbon of the porphyrin ring regioselectively under mild conditions. Chem Commun (Camb) 2013; 49:9296-8. [PMID: 24000351 DOI: 10.1039/c3cc44558e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reaction site of the Co(II) porphyrin created by an amide group and coordinating 1,2-dimethylimidazole at the fifth site activated an O2 molecule, and then hydroxylated the meso-carbon of the ligand. The biomimic O2 activation under mild conditions is described.
Collapse
Affiliation(s)
- Katsunori Yamanishi
- Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | | | | | | |
Collapse
|
19
|
Govender P, Pai S, Schatzschneider U, Smith GS. Next Generation PhotoCORMs: Polynuclear Tricarbonylmanganese(I)-Functionalized Polypyridyl Metallodendrimers. Inorg Chem 2013; 52:5470-8. [DOI: 10.1021/ic400377k] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Preshendren Govender
- Department of Chemistry, University
of Cape Town, Rondebosch, 7701, Cape Town, South Africa
| | - Sandesh Pai
- Institut für Anorganische
Chemie, Julius-Maximilians-Universität Würzburg, Am
Hubland, D-97074 Würzburg, Germany
| | - Ulrich Schatzschneider
- Institut für Anorganische
Chemie, Julius-Maximilians-Universität Würzburg, Am
Hubland, D-97074 Würzburg, Germany
| | - Gregory S. Smith
- Department of Chemistry, University
of Cape Town, Rondebosch, 7701, Cape Town, South Africa
| |
Collapse
|
20
|
Peng D, Ma LH, Smith KM, Zhang X, Sato M, La Mar GN. Role of propionates in substrate binding to heme oxygenase from Neisseria meningitidis: a nuclear magnetic resonance study. Biochemistry 2012; 51:7054-63. [PMID: 22913621 DOI: 10.1021/bi3007803] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Heme oxygenase (HO) cleaves hemin into biliverdin, iron, and CO. For mammalian HOs, both native hemin propionates are required for substrate binding and activity. The HO from the pathogenic bacterium Neisseria meningitidis (NmHO) possesses a crystallographically undetected C-terminal fragment that by solution (1)H nuclear magnetic resonance (NMR) is found to fold and interact with the active site. One of the substrate propionates has been proposed to form a salt bridge to the C-terminus rather than to the conventional buried cationic side chain in other HOs. Moreover, the C-terminal dipeptide Arg208His209 cleaves spontaneously over ~24 h at a rate dependent on substituent size. Two-dimensional (1)H NMR of NmHO azide complexes with hemins with selectively deleted or rearranged propionates shows that all bind to NmHO with a structurally conserved active site as reflected in optical spectra and NMR nuclear Overhauser effect spectroscopy cross-peak and hyperfine shift patterns. In contrast to mammalian HOs, NmHO requires only a single propionate interacting with the buried terminus of Lys16 to exhibit full activity and tolerates the existence of a propionate at the exposed 8-position. The structure of the C-terminus is qualitatively retained upon deletion of the 7-propionate, but a dramatic change in the 7-propionate carboxylate (13)C chemical shift upon C-terminal cleavage confirms its role in the interaction with the C-terminus. The stronger hydrophobic contacts between pyrroles A and B with NmHO contribute more substantially to the substrate binding free energy than in mammalian HOs, "liberating" one propionate to stabilize the C-terminus. The functional implications of the C-terminus in product release are discussed.
Collapse
Affiliation(s)
- Dungeng Peng
- Department of Chemistry, University of California, Davis, CA 95616, USA
| | | | | | | | | | | |
Collapse
|
21
|
Fukusumi T, Matsuda K, Mizoguchi T, Miyatake T, Ito S, Ikeda T, Tamiaki H, Oba T. Non-enzymatic conversion of chlorophyll-a into chlorophyll-d in vitro: a model oxidation pathway for chlorophyll-d biosynthesis. FEBS Lett 2012; 586:2338-41. [PMID: 22659188 DOI: 10.1016/j.febslet.2012.05.036] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 05/15/2012] [Accepted: 05/15/2012] [Indexed: 10/28/2022]
Abstract
Chlorophyll-a (Chl-a) was readily converted into Chl-d under mild conditions without any enzymes. Treatment of Chl-a dissolved in dry tetrahydrofuran (THF) with thiophenol and acetic acid at room temperature successfully produced Chl-d in 31% yield. During the acidic oxidation, removal of the central magnesium, pheophytinization, was sufficiently suppressed. This mild pathway can give insights into the yet unidentified Chl-d biosynthesis.
Collapse
Affiliation(s)
- Takanori Fukusumi
- Department of Material and Environmental Chemistry, Graduate School of Engineering, Utsunomiya University, Utsunomiya, Tochigi 321-8585, Japan
| | | | | | | | | | | | | | | |
Collapse
|
22
|
Crystallographic studies of heme oxygenase complexed with an unstable reaction intermediate, verdoheme. J Inorg Biochem 2012; 113:102-9. [PMID: 22673156 DOI: 10.1016/j.jinorgbio.2012.04.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Revised: 04/05/2012] [Accepted: 04/11/2012] [Indexed: 11/20/2022]
Abstract
This article discusses the accuracy of X-ray structural studies of heme oxygenase (HO) in complex with an unstable intermediate, verdoheme. Heme degradation by HO proceeds through three successive steps of O(2) activation. The mechanism of the third step, the ring opening of verdoheme, has been the least understood. Recent structural studies of the verdoheme-HO complex provide detailed information concerning this mechanism. Due to X-ray-induced photoreduction and the instability of verdoheme, it has been difficult to obtain an accurate structure for the ferrous verdoheme-HO complex. Therefore, accurate structural studies, including analysis of the electronic state of the verdoheme-HO complex, are needed to elucidate the proper reaction mechanism.
Collapse
|
23
|
Electronic properties of the highly ruffled heme bound to the heme degrading enzyme IsdI. Proc Natl Acad Sci U S A 2011; 108:13071-6. [PMID: 21788475 DOI: 10.1073/pnas.1101459108] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
IsdI, a heme-degrading protein from Staphylococcus aureus, binds heme in a manner that distorts the normally planar heme prosthetic group to an extent greater than that observed so far for any other heme-binding protein. To understand better the relationship between this distinct structural characteristic and the functional properties of IsdI, spectroscopic, electrochemical, and crystallographic results are reported that provide evidence that this heme ruffling is essential to the catalytic activity of the protein and eliminates the need for the water cluster in the distal heme pocket that is essential for the activity of classical heme oxygenases. The lack of heme orientational disorder in (1)H-NMR spectra of the protein argues that the catalytic formation of β- and δ-biliverdin in nearly equal yield results from the ability of the protein to attack opposite sides of the heme ring rather than from binding of the heme substrate in two alternative orientations.
Collapse
|
24
|
Gardner JD, Yi L, Ragsdale SW, Brunold TC. Spectroscopic insights into axial ligation and active-site H-bonding in substrate-bound human heme oxygenase-2. J Biol Inorg Chem 2010; 15:1117-27. [PMID: 20502928 PMCID: PMC2972362 DOI: 10.1007/s00775-010-0672-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Accepted: 04/21/2010] [Indexed: 10/19/2022]
Abstract
Heme oxygenases (HOs) are monooxygenases that catalyze the first step in heme degradation, converting heme to biliverdin with concomitant release of Fe(II) and CO from the porphyrin macrocycle. Two heme oxygenase isoforms, HO-1 and HO-2, exist that differ in several ways, including a complete lack of Cys residues in HO-1 and the presence of three Cys residues as part of heme-regulatory motifs (HRMs) in HO-2. HRMs in other heme proteins are thought to directly bind heme, or to otherwise regulate protein stability or activity; however, it is not currently known how the HRMs exert these effects on HO-2 function. To better understand the properties of this vital enzyme and to elucidate possible roles of its HRMs, various forms of HO-2 possessing distinct alterations to the HRMs were prepared. In this study, variants with Cys265 in a thiol form are compared with those with this residue in an oxidized (part of a disulfide bond or existing as a sulfenate moiety) form. Absorption and magnetic circular dichroism spectroscopic data of these HO-2 variants clearly demonstrate that a new low-spin Fe(III) heme species characteristic of thiolate ligation is formed when Cys265 is reduced. Additionally, absorption, magnetic circular dichroism, and resonance Raman data collected at different temperatures reveal an intriguing temperature dependence of the iron spin state in the heme-HO-2 complex. These findings are consistent with the presence of a hydrogen-bonding network at the heme's distal side within the active site of HO-2 with potentially significant differences from that observed in HO-1.
Collapse
Affiliation(s)
- Jessica D. Gardner
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI 53706, USA
| | - Li Yi
- Department of Biological Chemistry, University of Michigan Medical School, 1150 W. Medical Center Dr., Ann Arbor, MI 48109, USA
| | - Stephen W. Ragsdale
- Department of Biological Chemistry, University of Michigan Medical School, 1150 W. Medical Center Dr., Ann Arbor, MI 48109, USA
| | - Thomas C. Brunold
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI 53706, USA
| |
Collapse
|
25
|
Lai W, Chen H, Matsui T, Omori K, Unno M, Ikeda-Saito M, Shaik S. Enzymatic Ring-Opening Mechanism of Verdoheme by the Heme Oxygenase: A Combined X-ray Crystallography and QM/MM Study. J Am Chem Soc 2010; 132:12960-70. [DOI: 10.1021/ja104674q] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Wenzhen Lai
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel, and Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Sendai, 980-8577, Japan
| | - Hui Chen
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel, and Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Sendai, 980-8577, Japan
| | - Toshitaka Matsui
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel, and Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Sendai, 980-8577, Japan
| | - Kohei Omori
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel, and Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Sendai, 980-8577, Japan
| | - Masaki Unno
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel, and Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Sendai, 980-8577, Japan
| | - Masao Ikeda-Saito
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel, and Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Sendai, 980-8577, Japan
| | - Sason Shaik
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel, and Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Sendai, 980-8577, Japan
| |
Collapse
|
26
|
Matsui T, Iwasaki M, Sugiyama R, Unno M, Ikeda-Saito M. Dioxygen activation for the self-degradation of heme: reaction mechanism and regulation of heme oxygenase. Inorg Chem 2010; 49:3602-9. [PMID: 20380462 DOI: 10.1021/ic901869t] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Heme oxygenase (HO) catalyzes the regiospecific conversion of heme to biliverdin, CO, and free iron through three successive oxygenation reactions. HO catalysis is unique in that all three O(2) activations are performed by the substrate itself. This Forum Article overviews our current understanding on the structural and biochemical properties of HO catalysis, especially its first and third oxygenation steps. The HO first step, regiospecific hydroxylation of the porphyrin alpha-meso-carbon atom, is of particular interest because of its sharp contrast to O(2) activation by cytochrome P450. HO was proposed to utilize the FeOOH species but not conventional ferryl hemes as a reactive intermediate for self-hydroxylation. We have succeeded in preparing and characterizing the FeOOH species of HO at low temperature, and our analyses of its reaction, together with mutational and crystallographic studies, reveal that protonation of FeOOH by a distal water molecule is critical in promoting the unique self-hydroxylation. The second oxygenation is a rapid, spontaneous autooxidation of the reactive alpha-meso-hydroxyheme in which the HO enzyme does not play a critical role. Further O(2) activation by verdoheme cleaves its porphyrin macrocycle to form biliverdin and free ferrous iron. This third step has been considered to be a major rate-determining step of HO catalysis to regulate the enzyme activity. Our reaction analysis strongly supports the FeOOH verdoheme as the key intermediate of the ring-opening reaction. This mechanism is very similar to that of the first meso-hydroxylation, and the distal water is suggested to enhance the third step as expected from the similarity. The HO mechanistic studies highlight the catalytic importance of the distal hydrogen-bonding network, and this manuscript also involves our attempts to develop HO inhibitors targeting the unique distal structure.
Collapse
Affiliation(s)
- Toshitaka Matsui
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan.
| | | | | | | | | |
Collapse
|
27
|
Du Z, Unno M, Matsui T, Ikeda-Saito M, La Mar GN. Solution 1H NMR characterization of substrate-free C. diphtheriae heme oxygenase: pertinence for determining magnetic axes in paramagnetic substrate complexes. J Inorg Biochem 2010; 104:1063-70. [PMID: 20655112 DOI: 10.1016/j.jinorgbio.2010.06.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 06/03/2010] [Accepted: 06/16/2010] [Indexed: 11/28/2022]
Abstract
Proton 2D NMR was used to confirm in solution a highly conserved portion of the molecular structure upon substrate loss for the heme oxygenase from the pathogenic bacterium Corynebacterium diphtheriae, HmuO. The chemical shifts for the conserved portion of the structure are assessed as references for the dipolar shifts needed to determine the orientation of the paramagnetic susceptibility tensor, chi, in paramagnetic substrate complexes of HmuO. It is shown that the chemical shifts for the structurally conserved portion of substrate-free HmuO serve as excellent references for residues with only small to moderate sized dipolar shifts in the cyanide-inhibited substrate complex of HmuO, yielding an orientation of chi that is essentially the same as conventionally obtained from large dipolar shifts based on empirical estimates of the diamagnetic reference. The implications of these diamagnetic chemical shifts for characterizing the hydrogen bonding in the physiologically relevant, resting-state, high-spin aquo complex are discussed. The pattern of labile proton exchange in the distal H-bond network of substrate-free HmuO allowed comparison of changes in dynamic stability of tertiary contacts in the substrate-free and substrate-bound HmuO and with the same complexes of human heme oxygenase.
Collapse
Affiliation(s)
- Zhenming Du
- Department of Chemistry, University of California, Davis, CA 95616, USA.
| | | | | | | | | |
Collapse
|
28
|
Vidossich P, Fiorin G, Alfonso-Prieto M, Derat E, Shaik S, Rovira C. On the role of water in peroxidase catalysis: a theoretical investigation of HRP compound I formation. J Phys Chem B 2010; 114:5161-9. [PMID: 20345187 DOI: 10.1021/jp911170b] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have investigated the dynamics of water molecules in the distal pocket of horseradish peroxidase to elucidate the role that they may play in the formation of the principal active species of the enzymatic cycle (compound I, Por(o+)-Fe(IV)=O) upon reaction of the resting Fe(III) state with hydrogen peroxide. The equilibrium molecular dynamics simulations show that, in accord with experimental evidence, the active site access channel is hydrated with an average of two to three water molecules within 5 A from the bound hydrogen peroxide. Although the channel is always hydrated, the specific conformations in which a water molecule bridges H(2)O(2) and the distal histidine, which were found (Derat; et al. J. Am. Chem. Soc. 2007, 129, 6346.) to display a low-energy barrier for the initial acid-base step of the reaction, occur with low probability but are relevant within the time scale of catalysis. Metadynamics simulations, which were used to reconstruct the free-energy landscape of water motion in the access channel, revealed that preferred interaction sites within the channel are separated by small energy barriers (<1.5 kcal/mol). Most importantly, water-bridged conformations lie on a shoulder just 1 kcal/mol above one local minimum and thus are easily accessible. Such an energy landscape appears as a requisite for the effectiveness of compound I formation, whereby the H-bonding pattern involving reactants and catalytic residues (including the intervening water molecule) has to rearrange to deliver the proton to the distal OH moiety of the hydrogen peroxide and thereby lead to heterolytic O-O cleavage. Our study provides an example of a system for which the "reactive configurations" (i.e., structures characterized by a low barrier for the chemical transformation) correspond to a minor population of the system and show how equilibrium molecular dynamics and free-energy calculations may conveniently be used to ascertain that such reactive conformations are indeed accessible to the system. Once again, the MD and QM/MM combination shows that a single water molecule acts as a biocatalyst in the cycle of HRP.
Collapse
Affiliation(s)
- Pietro Vidossich
- Laboratori de Simulació Computacional i Modelització, Parc Científic de Barcelona, Josep Samitier 1-5, 08028 Barcelona, Spain
| | | | | | | | | | | |
Collapse
|
29
|
Reniere ML, Ukpabi GN, Harry SR, Stec DF, Krull R, Wright DW, Bachmann BO, Murphy ME, Skaar EP. The IsdG-family of haem oxygenases degrades haem to a novel chromophore. Mol Microbiol 2010; 75:1529-38. [PMID: 20180905 DOI: 10.1111/j.1365-2958.2010.07076.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Enzymatic haem catabolism by haem oxygenases is conserved from bacteria to humans and proceeds through a common mechanism leading to the formation of iron, carbon monoxide and biliverdin. The first members of a novel class of haem oxygenases were recently identified in Staphylococcus aureus (IsdG and IsdI) and were termed the IsdG-family of haem oxygenases. Enzymes of the IsdG-family form tertiary structures distinct from those of the canonical haem oxygenase family, suggesting that IsdG-family members degrade haem via a unique reaction mechanism. Herein we report that the IsdG-family of haem oxygenases degrade haem to the oxo-bilirubin chromophore staphylobilin. We also present the crystal structure of haem-bound IsdI in which haem ruffling and constrained binding of oxygen is consistent with cleavage of the porphyrin ring at the beta- or delta-meso carbons. Combined, these data establish that the IsdG-family of haem oxygenases degrades haem to a novel chromophore distinct from biliverdin.
Collapse
Affiliation(s)
- Michelle L Reniere
- Department of Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Matsui T, Unno M, Ikeda-Saito M. Heme oxygenase reveals its strategy for catalyzing three successive oxygenation reactions. Acc Chem Res 2010; 43:240-7. [PMID: 19827796 DOI: 10.1021/ar9001685] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Heme oxygenase (HO) is an enzyme that catalyzes the regiospecific conversion of heme to biliverdin IXalpha, CO, and free iron. In mammals, HO has a variety of physiological functions, including heme catabolism, iron homeostasis, antioxidant defense, cellular signaling, and O(2) sensing. The enzyme is also found in plants (producing light-harvesting pigments) and in some pathogenic bacteria, where it acquires iron from the host heme. The HO-catalyzed heme conversion proceeds through three successive oxygenations, a process that has attracted considerable attention because of its reaction mechanism and physiological importance. The HO reaction is unique in that all three O(2) activations are affected by the substrate itself. The first step is the regiospecific self-hydroxylation of the porphyrin alpha-meso carbon atom. The resulting alpha-meso-hydroxyheme reacts in the second step with another O(2) to yield verdoheme and CO. The third O(2) activation, by verdoheme, cleaves its porphyrin macrocycle to release biliverdin and free ferrous iron. In this Account, we provide an overview of our current understanding of the structural and biochemical properties of the complex self-oxidation reactions in HO catalysis. The first meso-hydroxylation is of particular interest because of its distinct contrast with O(2) activation by cytochrome P450. Although most heme enzymes oxidize exogenous substrates by high-valent oxo intermediates, HO was proposed to utilize the Fe-OOH intermediate for the self-hydroxylation. We have succeeded in preparing and characterizing the Fe-OOH species of HO at low temperature, and an analysis of its reaction, together with mutational and crystallographic studies, reveals that protonation of Fe-OOH by a distal water molecule is critical in promoting the unique self-hydroxylation. The second oxygenation is a rapid, spontaneous auto-oxidation of the reactive alpha-meso-hydroxyheme; its mechanism remains elusive, but the HO enzyme has been shown not to play a critical role in it. Until recently, the means of the third O(2) activation had remained unclear as well, but we have recently untangled its mechanistic outline. Reaction analysis of the verdoheme-HO complex strongly suggests the Fe-OOH species as a key intermediate of the ring-opening reaction. This mechanism is very similar to that of the first meso-hydroxylation, including the critical roles of the distal water molecule. A comprehensive study of the three oxygenations of HO highlights the rational design of the enzyme architecture and its catalytic mechanism. Elucidation of the last oxygenation step has enabled a kinetic analysis of the rate-determining step, making it possible to discuss the HO reaction mechanism in relation to its physiological functions.
Collapse
Affiliation(s)
- Toshitaka Matsui
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan
| | - Masaki Unno
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan
| | - Masao Ikeda-Saito
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan
| |
Collapse
|
31
|
Peng D, Ogura H, Zhu W, Ma LH, Evans JP, Ortiz de Montellano PR, La Mar GN. Coupling of the distal hydrogen bond network to the exogenous ligand in substrate-bound, resting state human heme oxygenase. Biochemistry 2009; 48:11231-42. [PMID: 19842713 DOI: 10.1021/bi901216s] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mammalian heme oxygenase (HO) possesses catalytically implicated distal ordered water molecules within an extended H-bond network, with one of the ordered water molecules (#1) providing a bridge between the iron-coordinated ligand and the catalytically critical Asp140, that, in turn, serves as an acceptor for the Tyr58 OH H-bond. The degree of H-bonding by the ligated water molecule and the coupling of this water molecule to the H-bond network are of current interest and are herein investigated by (1)H NMR. Two-dimensional NMR allowed sufficient assignments to provide both the H-bond strength and hyperfine shifts, the latter of which were used to quantify the magnetic anisotropy in both the ferric high-spin aquo and low-spin hydroxo complexes. The anisotropy in the aquo complex indicates that the H-bond donation to water #1 is marginally stronger than in a bacterial HO, while the anisotropy for the hydroxo complex reveals a conventional (d(xz), d(yz))(1) ground state indicative of only moderate to weak H-bond acceptance by the ligated hydroxide. Mapping out the changes of the H-bond strengths in the network during the ligated water --> hydroxide conversion by correcting for the effects of magnetic anisotropy reveals a very substantial change in H-bond strength for Tyr58 OH and lesser effects on nearby H-bonds. The effect of pH on the H-bonding network in human HO is much larger and transmitted much further from the iron than in a pathogenic bacterial HO. The implications for the HO mechanism of the H-bond of Tyr58 to Asp140 are discussed.
Collapse
Affiliation(s)
- Dungeng Peng
- Department of Chemistry, University of California, Davis, California 95616, USA
| | | | | | | | | | | | | |
Collapse
|
32
|
Ogura H, Evans JP, Peng D, Satterlee JD, Ortiz de Montellano PR, La Mar GN. The orbital ground state of the azide-substrate complex of human heme oxygenase is an indicator of distal H-bonding: implications for the enzyme mechanism. Biochemistry 2009; 48:3127-37. [PMID: 19243105 DOI: 10.1021/bi802360g] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The active site electronic structure of the azide complex of substrate-bound human heme oxygenase 1 (hHO) has been investigated by (1)H NMR spectroscopy to shed light on the orbital/spin ground state as an indicator of the unique distal pocket environment of the enzyme. Two-dimensional (1)H NMR assignments of the substrate and substrate-contact residue signals reveal a pattern of substrate methyl contact shifts that places the lone iron pi-spin in the d(xz) orbital, rather than the d(yz) orbital found in the cyanide complex. Comparison of iron spin relaxivity, magnetic anisotropy, and magnetic susceptibilities argues for a low-spin, (d(xy))(2)(d(yz),d(xz))(3), ground state in both azide and cyanide complexes. The switch from singly occupied d(yz) for the cyanide to d(xz) for the azide complex of hHO is shown to be consistent with the orbital hole determined by the azide pi-plane in the latter complex, which is approximately 90 degrees in-plane rotated from that of the imidazole pi-plane. The induction of the altered orbital ground state in the azide relative to the cyanide hHO complex, as well as the mean low-field bias of methyl hyperfine shifts and their paramagnetic relaxivity relative to those in globins, indicates that azide exerts a stronger ligand field in hHO than in the globins, or that the distal H-bonding to azide is weaker in hHO than in globins. The Asp140 --> Ala hHO mutant that abolishes activity retains the unusual WT azide complex spin/orbital ground state. The relevance of our findings for other HO complexes and the HO mechanism is discussed.
Collapse
Affiliation(s)
- Hiroshi Ogura
- Department of Chemistry, University of California, Davis, California 95616, USA
| | | | | | | | | | | |
Collapse
|
33
|
Ma LH, Liu Y, Zhang X, Yoshida T, La Mar GN. 1H NMR study of the effect of variable ligand on heme oxygenase electronic and molecular structure. J Inorg Biochem 2008; 103:10-9. [PMID: 18976815 DOI: 10.1016/j.jinorgbio.2008.08.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 07/16/2008] [Accepted: 08/26/2008] [Indexed: 11/28/2022]
Abstract
Heme oxygenase carries out stereospecific catabolism of protohemin to yield iron, CO and biliverdin. Instability of the physiological oxy complex has necessitated the use of model ligands, of which cyanide and azide are amenable to solution NMR characterization. Since cyanide and azide are contrasting models for bound oxygen, it is of interest to characterize differences in their molecular and/or electronic structures. We report on detailed 2D NMR comparison of the azide and cyanide substrate complexes of heme oxygenase from Neisseria meningitidis, which reveals significant and widespread differences in chemical shifts between the two complexes. To differentiate molecular from electronic structural changes between the two complexes, the anisotropy and orientation of the paramagnetic susceptibility tensor were determined for the azide complex for comparison with those for the cyanide complex. Comparison of the predicted and observed dipolar shifts reveals that shift differences are strongly dominated by differences in electronic structure and do not provide any evidence for detectable differences in molecular structure or hydrogen bonding except in the immediate vicinity of the distal ligand. The readily cleaved C-terminus interacts with the active site and saturation-transfer allows difficult heme assignments in the high-spin aquo complex.
Collapse
Affiliation(s)
- Li-Hua Ma
- Department of Chemistry, University of California, Davis, CA 95616, United States
| | | | | | | | | |
Collapse
|
34
|
Chen H, Moreau Y, Derat E, Shaik S. Quantum Mechanical/Molecular Mechanical Study of Mechanisms of Heme Degradation by the Enzyme Heme Oxygenase: The Strategic Function of the Water Cluster. J Am Chem Soc 2008; 130:1953-65. [DOI: 10.1021/ja076679p] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Hui Chen
- Department of Organic Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel
| | - Yohann Moreau
- Department of Organic Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel
| | - Etienne Derat
- Department of Organic Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel
| | - Sason Shaik
- Department of Organic Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel
| |
Collapse
|
35
|
Gherardini PF, Wass MN, Helmer-Citterich M, Sternberg MJE. Convergent Evolution of Enzyme Active Sites Is not a Rare Phenomenon. J Mol Biol 2007; 372:817-45. [PMID: 17681532 DOI: 10.1016/j.jmb.2007.06.017] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2006] [Revised: 05/14/2007] [Accepted: 06/08/2007] [Indexed: 02/03/2023]
Abstract
Since convergent evolution of enzyme active sites was first identified in serine proteases, other individual instances of this phenomenon have been documented. However, a systematic analysis assessing the frequency of this phenomenon across enzyme space is still lacking. This work uses the Query3d structural comparison algorithm to integrate for the first time detailed knowledge about catalytic residues, available through the Catalytic Site Atlas (CSA), with the evolutionary information provided by the Structural Classification of Proteins (SCOP) database. This study considers two modes of convergent evolution: (i) mechanistic analogues which are enzymes that use the same mechanism to perform related, but possibly different, reactions (considered here as sharing the first three digits of the EC number); and (ii) transformational analogues which catalyse exactly the same reaction (identical EC numbers), but may use different mechanisms. Mechanistic analogues were identified in 15% (26 out of 169) of the three-digit EC groups considered, showing that this phenomenon is not rare. Furthermore 11 of these groups also contain transformational analogues. The catalytic triad is the most widespread active site; the results of the structural comparison show that this mechanism, or variations thereof, is present in 23 superfamilies. Transformational analogues were identified for 45 of the 951 four-digit EC numbers present within the CSA and about half of these were also mechanistic analogues exhibiting convergence of their active sites. This analysis has also been extended to the whole Protein Data Bank to provide a complete and manually curated list of the all the transformational analogues whose structure is classified in SCOP. The results of this work show that the phenomenon of convergent evolution is not rare, especially when considering large enzymatic families.
Collapse
Affiliation(s)
- Pier Federico Gherardini
- Biochemistry Building, Division of Molecular Biosciences, Imperial College London, London SW7 2AZ, UK
| | | | | | | |
Collapse
|
36
|
Affiliation(s)
- Stephen W Ragsdale
- Department of Biochemistry, Beadle Center, University of Nebraska, Lincoln, Nebraska 68588-0664, USA.
| |
Collapse
|
37
|
Unno M, Matsui T, Ikeda-Saito M. Structure and catalytic mechanism of heme oxygenase. Nat Prod Rep 2007; 24:553-70. [PMID: 17534530 DOI: 10.1039/b604180a] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Masaki Unno
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
| | | | | |
Collapse
|
38
|
Garcia-Serres R, Davydov RM, Matsui T, Ikeda-Saito M, Hoffman BM, Huynh BH. Distinct reaction pathways followed upon reduction of oxy-heme oxygenase and oxy-myoglobin as characterized by Mössbauer spectroscopy. J Am Chem Soc 2007; 129:1402-12. [PMID: 17263425 PMCID: PMC2519892 DOI: 10.1021/ja067209i] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Activation of O(2) by heme-containing monooxygenases generally commences with the common initial steps of reduction to the ferrous heme and binding of O(2) followed by a one-electron reduction of the O(2)-bound heme. Subsequent steps that generate reactive oxygen intermediates diverge and reflect the effects of protein control on the reaction pathway. In this study, Mössbauer and EPR spectroscopies were used to characterize the electronic states and reaction pathways of reactive oxygen intermediates generated by 77 K radiolytic cryoreduction and subsequent annealing of oxy-heme oxygenase (HO) and oxy-myoglobin (Mb). The results confirm that one-electron reduction of (Fe(II)-O(2))HO is accompanied by protonation of the bound O(2) to generate a low-spin (Fe(III)-O(2)H(-))HO that undergoes self-hydroxylation to form the alpha-meso-hydroxyhemin-HO product. In contrast, one-electron reduction of (Fe(II)-O(2))Mb yields a low-spin (Fe(III)-O(2)(2-))Mb. Protonation of this intermediate generates (Fe(III)-O(2)H(-))Mb, which then decays to a ferryl complex, (Fe(IV)=O(2-))Mb, that exhibits magnetic properties characteristic of the compound II species generated in the reactions of peroxide with heme peroxidases and with Mb. Generation of reactive high-valent states with ferryl species via hydroperoxo intermediates is believed to be the key oxygen-activation steps involved in the catalytic cycles of P450-type monooxygenases. The Mössbauer data presented here provide direct spectroscopic evidence supporting the idea that ferric-hydroperoxo hemes are indeed the precursors of the reactive ferryl intermediates. The fact that a ferryl intermediate does not accumulate in HO underscores the determining role played by protein structure in controlling the reactivity of reaction intermediates.
Collapse
Affiliation(s)
| | | | | | - Masao Ikeda-Saito
- *To whom correspondence should be addressed. B.H.H: telephone, 404-727-4295; fax, 404-727-0873; email, . B.M.H., telephone, 847-491-3104; fax: 847-491-7713; email, . M.I.S.: telephone, +81-22-217-5116; fax, +81-22-217-5118; email,
| | - Brian M. Hoffman
- *To whom correspondence should be addressed. B.H.H: telephone, 404-727-4295; fax, 404-727-0873; email, . B.M.H., telephone, 847-491-3104; fax: 847-491-7713; email, . M.I.S.: telephone, +81-22-217-5116; fax, +81-22-217-5118; email,
| | - Boi Hanh Huynh
- *To whom correspondence should be addressed. B.H.H: telephone, 404-727-4295; fax, 404-727-0873; email, . B.M.H., telephone, 847-491-3104; fax: 847-491-7713; email, . M.I.S.: telephone, +81-22-217-5116; fax, +81-22-217-5118; email,
| |
Collapse
|
39
|
|
40
|
Abstract
Inorganic chemistry and biology can benefit greatly from each other. Although synthetic and physical inorganic chemistry have been greatly successful in clarifying the role of metal ions in biological systems, the time may now be right to utilize biological systems to advance coordination chemistry. One such example is the use of small, stable, easy-to-make, and well-characterized proteins as ligands to synthesize novel inorganic compounds. This biosynthetic inorganic chemistry is possible thanks to a number of developments in biology. This review summarizes the progress in the synthesis of close models of complex metalloproteins, followed by a description of recent advances in using the approach for making novel compounds that are unprecedented in either inorganic chemistry or biology. The focus is mainly on synthetic "tricks" learned from biology, as well as novel structures and insights obtained. The advantages and disadvantages of this biosynthetic approach are discussed.
Collapse
Affiliation(s)
- Yi Lu
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| |
Collapse
|
41
|
Terner J, Palaniappan V, Gold A, Weiss R, Fitzgerald MM, Sullivan AM, Hosten CM. Resonance Raman spectroscopy of oxoiron(IV) porphyrin π-cation radical and oxoiron(IV) hemes in peroxidase intermediates. J Inorg Biochem 2006; 100:480-501. [PMID: 16513173 DOI: 10.1016/j.jinorgbio.2006.01.008] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Accepted: 01/04/2006] [Indexed: 11/15/2022]
Abstract
The catalytic cycle intermediates of heme peroxidases, known as compounds I and II, have been of long standing interest as models for intermediates of heme proteins, such as the terminal oxidases and cytochrome P450 enzymes, and for non-heme iron enzymes as well. Reports of resonance Raman signals for compound I intermediates of the oxo-iron(IV) porphyrin pi-cation radical type have been sometimes contradictory due to complications arising from photolability, causing compound I signals to appear similar to those of compound II or other forms. However, studies of synthetic systems indicated that protein based compound I intermediates of the oxoiron(IV) porphyrin pi-cation radical type should exhibit vibrational signatures that are different from the non-radical forms. The compound I intermediates of horseradish peroxidase (HRP), and chloroperoxidase (CPO) from Caldariomyces fumago do in fact exhibit unique and characteristic vibrational spectra. The nature of the putative oxoiron(IV) bond in peroxidase intermediates has been under discussion in the recent literature, with suggestions that the Fe(IV)O unit might be better described as Fe(IV)-OH. The generally low Fe(IV)O stretching frequencies observed for proteins have been difficult to mimic in synthetic ferryl porphyrins via electron donation from trans axial ligands alone. Resonance Raman studies of iron-oxygen vibrations within protein species that are sensitive to pH, deuteration, and solvent oxygen exchange, indicate that hydrogen bonding to the oxoiron(IV) group within the protein environment contributes to substantial lowering of Fe(IV)O frequencies relative to those of synthetic model compounds.
Collapse
Affiliation(s)
- James Terner
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284-2006, USA.
| | | | | | | | | | | | | |
Collapse
|
42
|
|
43
|
Kikuchi G, Yoshida T, Noguchi M. Heme oxygenase and heme degradation. Biochem Biophys Res Commun 2005; 338:558-67. [PMID: 16115609 DOI: 10.1016/j.bbrc.2005.08.020] [Citation(s) in RCA: 300] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2005] [Accepted: 08/03/2005] [Indexed: 01/05/2023]
Abstract
The microsomal heme oxygenase system consists of heme oxygenase (HO) and NADPH-cytochrome P450 reductase, and plays a key role in the physiological catabolism of heme which yields biliverdin, carbon monoxide, and iron as the final products. Heme degradation proceeds essentially as a series of autocatalytic oxidation reactions involving heme bound to HO. Large amounts of HO proteins from human and rat can now be prepared in truncated soluble form, and the crystal structures of some HO proteins have been determined. These advances have greatly facilitated the understanding of the mechanisms of individual steps of the HO reaction. HO can be induced in animals by the administration of heme or several other substances; the induction is shown to involve Bach1, a translational repressor. The induced HO is assumed to have cytoprotective effects. An uninducible HO isozyme, HO-2, has been identified, so the authentic HO is now called HO-1. HOs are also widely distributed in invertebrates, higher plants, algae, and bacteria, and function in various ways according to the needs of individual species.
Collapse
Affiliation(s)
- Goro Kikuchi
- Tohoku University School of Medicine, Sendai, Japan
| | | | | |
Collapse
|
44
|
Matsui T, Nakajima A, Fujii H, Matera KM, Migita CT, Yoshida T, Ikeda-Saito M. O(2)- and H(2)O(2)-dependent verdoheme degradation by heme oxygenase: reaction mechanisms and potential physiological roles of the dual pathway degradation. J Biol Chem 2005; 280:36833-40. [PMID: 16115896 DOI: 10.1074/jbc.m503529200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Heme oxygenase (HO) catalyzes the catabolism of heme to biliverdin, CO, and a free iron through three successive oxygenation steps. The third oxygenation, oxidative degradation of verdoheme to biliverdin, has been the least understood step despite its importance in regulating HO activity. We have examined in detail the degradation of a synthetic verdoheme IXalpha complexed with rat HO-1. Our findings include: 1) HO degrades verdoheme through a dual pathway using either O(2) or H(2)O(2); 2) the verdoheme reactivity with O(2) is the lowest among the three O(2) reactions in the HO catalysis, and the newly found H(2)O(2) pathway is approximately 40-fold faster than the O(2)-dependent verdoheme degradation; 3) both reactions are initiated by the binding of O(2) or H(2)O(2) to allow the first direct observation of degradation intermediates of verdoheme; and 4) Asp(140) in HO-1 is critical for the verdoheme degradation regardless of the oxygen source. On the basis of these findings, we propose that the HO enzyme activates O(2) and H(2)O(2) on the verdoheme iron with the aid of a nearby water molecule linked with Asp(140). These mechanisms are similar to the well established mechanism of the first oxygenation, meso-hydroxylation of heme, and thus, HO can utilize a common architecture to promote the first and third oxygenation steps of the heme catabolism. In addition, our results infer the possible involvement of the H(2)O(2)-dependent verdoheme degradation in vivo, and potential roles of the dual pathway reaction of HO against oxidative stress are proposed.
Collapse
Affiliation(s)
- Toshitaka Matsui
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan
| | | | | | | | | | | | | |
Collapse
|