1
|
Prioretti L, D’Ermo G, Infossi P, Kpebe A, Lebrun R, Bauzan M, Lojou E, Guigliarelli B, Giudici-Orticoni MT, Guiral M. Carbon Fixation in the Chemolithoautotrophic Bacterium Aquifex aeolicus Involves Two Low-Potential Ferredoxins as Partners of the PFOR and OGOR Enzymes. Life (Basel) 2023; 13:life13030627. [PMID: 36983784 PMCID: PMC10052474 DOI: 10.3390/life13030627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/21/2023] [Accepted: 02/22/2023] [Indexed: 02/27/2023] Open
Abstract
Aquifex aeolicus is a microaerophilic hydrogen- and sulfur -oxidizing bacterium that assimilates CO2 via the reverse tricarboxylic acid cycle (rTCA). Key enzymes of this pathway are pyruvate:ferredoxin oxidoreductase (PFOR) and 2-oxoglutarate:ferredoxin oxidoreductase (OGOR), which are responsible, respectively, for the reductive carboxylation of acetyl-CoA to pyruvate and of succinyl-CoA to 2-oxoglutarate, two energetically unfavorable reactions that require a strong reduction potential. We have confirmed, by biochemistry and proteomics, that A. aeolicus possesses a pentameric version of these enzyme complexes ((αβγδε)2) and that they are highly abundant in the cell. In addition, we have purified and characterized, from the soluble fraction of A. aeolicus, two low redox potential and oxygen-stable [4Fe-4S] ferredoxins (Fd6 and Fd7, E0 = −440 and −460 mV, respectively) and shown that they can physically interact and exchange electrons with both PFOR and OGOR, suggesting that they could be the physiological electron donors of the system in vivo. Shotgun proteomics indicated that all the enzymes assumed to be involved in the rTCA cycle are produced in the A. aeolicus cells. A number of additional enzymes, previously suggested to be part of a putative partial Wood-Ljungdahl pathway used for the synthesis of serine and glycine from CO2 were identified by mass spectrometry, but their abundance in the cell seems to be much lower than that of the rTCA cycle. Their possible involvement in carbon assimilation is discussed.
Collapse
Affiliation(s)
- Laura Prioretti
- CNRS, Bioénergétique et Ingénierie des Protéines, Aix Marseille Université, IMM, 13009 Marseille, France
| | - Giulia D’Ermo
- CNRS, Bioénergétique et Ingénierie des Protéines, Aix Marseille Université, IMM, 13009 Marseille, France
| | - Pascale Infossi
- CNRS, Bioénergétique et Ingénierie des Protéines, Aix Marseille Université, IMM, 13009 Marseille, France
| | - Arlette Kpebe
- CNRS, Bioénergétique et Ingénierie des Protéines, Aix Marseille Université, IMM, 13009 Marseille, France
| | - Régine Lebrun
- CNRS, Aix Marseille Université, IMM, 13009 Marseille, France
| | - Marielle Bauzan
- CNRS, Aix Marseille Université, IMM, 13009 Marseille, France
| | - Elisabeth Lojou
- CNRS, Bioénergétique et Ingénierie des Protéines, Aix Marseille Université, IMM, 13009 Marseille, France
| | - Bruno Guigliarelli
- CNRS, Bioénergétique et Ingénierie des Protéines, Aix Marseille Université, IMM, 13009 Marseille, France
| | | | - Marianne Guiral
- CNRS, Bioénergétique et Ingénierie des Protéines, Aix Marseille Université, IMM, 13009 Marseille, France
- Correspondence:
| |
Collapse
|
2
|
Szyttenholm J, Chaspoul F, Bauzan M, Ducluzeau AL, Chehade MH, Pierrel F, Denis Y, Nitschke W, Schoepp-Cothenet B. The controversy on the ancestral arsenite oxidizing enzyme; deducing evolutionary histories with phylogeny and thermodynamics. Biochim Biophys Acta Bioenerg 2020; 1861:148252. [PMID: 32569664 DOI: 10.1016/j.bbabio.2020.148252] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 06/07/2020] [Accepted: 06/12/2020] [Indexed: 12/12/2022]
Abstract
The three presently known enzymes responsible for arsenic-using bioenergetic processes are arsenite oxidase (Aio), arsenate reductase (Arr) and alternative arsenite oxidase (Arx), all of which are molybdoenzymes from the vast group referred to as the Mo/W-bisPGD enzyme superfamily. Since arsenite is present in substantial amounts in hydrothermal environments, frequently considered as vestiges of primordial biochemistry, arsenite-based bioenergetics has long been predicted to be ancient. Conflicting scenarios, however, have been put forward proposing either Arr/Arx or Aio as operating in the ancestral metabolism. Phylogenetic data argue in favor of Aio whereas biochemical and physiological data led several authors to propose Arx/Arr as the most ancient anaerobic arsenite metabolizing enzymes. Here we combine phylogenetic approaches with physiological and biochemical experiments to demonstrate that the Arx/Arr enzymes could not have been functional in the Archaean geological eon. We propose that Arr reacts with menaquinones to reduce arsenate whereas Arx reacts with ubiquinone to oxidize arsenite, in line with thermodynamic considerations. The distribution of the quinone biosynthesis pathways, however, clearly indicates that the ubiquinone pathway is recent. An updated phylogeny of Arx furthermore reinforces the hypothesis of a recent emergence of this enzyme. We therefore conclude that anaerobic arsenite redox conversion in the Archaean must have been performed in a metabolism involving Aio.
Collapse
Affiliation(s)
- Julie Szyttenholm
- Aix-Marseille Univ., CNRS, BIP UMR 7281, FR 3479, IMM, 13402 Marseille Cedex 20, France
| | - Florence Chaspoul
- Aix Marseille Univ., CNRS, IRD, IMBE UMR 7263, Faculté de Pharmacie, 13005 Marseille, France
| | - Marielle Bauzan
- Aix-Marseille Univ., CNRS, Plateforme Fermentation, FR3479, IMM, 13402 Marseille Cedex 20, France
| | - Anne-Lise Ducluzeau
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775-7220, USA
| | | | - Fabien Pierrel
- Univ. Grenoble Alpes, CNRS, Grenoble INP, TIMC-IMAG, 38000 Grenoble, France
| | - Yann Denis
- Aix-Marseille Univ., CNRS, Plateforme Transcriptomique, FR3479, IMM, 13402 Marseille Cedex 20, France
| | - Wolfgang Nitschke
- Aix-Marseille Univ., CNRS, BIP UMR 7281, FR 3479, IMM, 13402 Marseille Cedex 20, France
| | | |
Collapse
|
3
|
Wang X, Clément R, Roger M, Bauzan M, Mazurenko I, Poulpiquet AD, Ilbert M, Lojou E. Bacterial Respiratory Chain Diversity Reveals a Cytochrome c Oxidase Reducing O 2 at Low Overpotentials. J Am Chem Soc 2019; 141:11093-11102. [PMID: 31274287 DOI: 10.1021/jacs.9b03268] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cytochrome c oxidases (CcOs) are the terminal enzymes in energy-converting chains of microorganisms, where they reduce oxygen into water. Their affinity for O2 makes them attractive biocatalysts for technological devices in which O2 concentration is limited, but the high overpotentials they display on electrodes severely limit their applicative use. Here, the CcO of the acidophilic bacterium Acidithiobacillus ferrooxidans is studied on various carbon materials by direct protein electrochemistry and mediated one with redox mediators either diffusing or co-immobilized at the electrode surface. The entrapment of the CcO in a network of hydrophobic carbon nanofibers permits a direct electrochemical communication between the enzyme and the electrode. We demonstrate that the CcO displays a μM affinity for O2 and reduces O2 at exceptionally high electrode potentials in the range of +700 to +540 mV vs NHE over a pH range of 4-6. The kinetics of interactions between the enzyme and its physiological partners are fully quantified. Based on these results, an electron transfer pathway allowing O2 reduction in the acidic metabolic chain is proposed.
Collapse
Affiliation(s)
- Xie Wang
- Aix-Marseille Univ , CNRS, BIP UMR 7281, 31 Chemin Aiguier , CS 70071, 13402 Marseille Cedex 09 , France
| | - Romain Clément
- Aix-Marseille Univ , CNRS, BIP UMR 7281, 31 Chemin Aiguier , CS 70071, 13402 Marseille Cedex 09 , France
| | - Magali Roger
- School of Natural and Environmental Sciences , Newcastle University , Devonshire Building , NE1 7RX , Newcastle upon Tyne , England
| | - Marielle Bauzan
- Aix-Marseille Univ , CNRS, IMM FR 3479, 31 Chemin Aiguier , 13009 Marseille , France
| | - Ievgen Mazurenko
- Aix-Marseille Univ , CNRS, BIP UMR 7281, 31 Chemin Aiguier , CS 70071, 13402 Marseille Cedex 09 , France
| | - Anne de Poulpiquet
- Aix-Marseille Univ , CNRS, BIP UMR 7281, 31 Chemin Aiguier , CS 70071, 13402 Marseille Cedex 09 , France
| | - Marianne Ilbert
- Aix-Marseille Univ , CNRS, BIP UMR 7281, 31 Chemin Aiguier , CS 70071, 13402 Marseille Cedex 09 , France
| | - Elisabeth Lojou
- Aix-Marseille Univ , CNRS, BIP UMR 7281, 31 Chemin Aiguier , CS 70071, 13402 Marseille Cedex 09 , France
| |
Collapse
|
4
|
Roger M, Sciara G, Biaso F, Lojou E, Wang X, Bauzan M, Giudici-Orticoni MT, Vila AJ, Ilbert M. Impact of copper ligand mutations on a cupredoxin with a green copper center. Biochimica et Biophysica Acta (BBA) - Bioenergetics 2017; 1858:351-359. [DOI: 10.1016/j.bbabio.2017.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/10/2017] [Accepted: 02/14/2017] [Indexed: 11/26/2022]
|
5
|
Barca C, Ranava D, Bauzan M, Ferrasse JH, Giudici-Orticoni MT, Soric A. Fermentative hydrogen production in an up-flow anaerobic biofilm reactor inoculated with a co-culture of Clostridium acetobutylicum and Desulfovibrio vulgaris. Bioresour Technol 2016; 221:526-533. [PMID: 27686721 DOI: 10.1016/j.biortech.2016.09.072] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/15/2016] [Accepted: 09/16/2016] [Indexed: 06/06/2023]
Abstract
Dark fermentation systems often show low H2 yields and unstable H2 production, as the result of the variability of microbial dynamics and metabolic pathways. Recent batch investigations have demonstrated that an artificial consortium of two anaerobic bacteria, Clostridium acetobutylicum and Desulfovibrio vulgaris Hildenborough, may redirect metabolic fluxes and improve H2 yields. This study aimed at evaluating the scale-up from batch to continuous H2 production in an up-flow anaerobic packed-bed reactor (APBR) continuously fed with a glucose-medium. The effects of various parameters, including void hydraulic retention time (HRTv), pH, and alkalinity, on H2 production performances and metabolic pathways were investigated. The results demonstrated that a stable H2 production was reached after 3-4days of operation. H2 production rates increased significantly with decreasing HRTv from 4 to 2h. Instead, H2 yields remained almost stable despite the change in HRTv, indicating that the decrease in HRTv did not affect the global metabolism.
Collapse
Affiliation(s)
- Cristian Barca
- Aix Marseille Univ, CNRS, Centrale Marseille, M2P2, Marseille, France
| | - David Ranava
- CNRS, Aix Marseille Univ, BIP, Marseille, France
| | | | | | | | - Audrey Soric
- Aix Marseille Univ, CNRS, Centrale Marseille, M2P2, Marseille, France; CNRS, Aix Marseille Univ, BIP, Marseille, France.
| |
Collapse
|
6
|
Boughanemi S, Lyonnet J, Infossi P, Bauzan M, Kosta A, Lignon S, Giudici-Orticoni MT, Guiral M. Microbial oxidative sulfur metabolism: biochemical evidence of the membrane-bound heterodisulfide reductase-like complex of the bacteriumAquifex aeolicus. FEMS Microbiol Lett 2016; 363:fnw156. [DOI: 10.1093/femsle/fnw156] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/06/2016] [Indexed: 11/13/2022] Open
|
7
|
Castelle CJ, Roger M, Bauzan M, Brugna M, Lignon S, Nimtz M, Golyshina OV, Giudici-Orticoni MT, Guiral M. The aerobic respiratory chain of the acidophilic archaeon Ferroplasma acidiphilum: A membrane-bound complex oxidizing ferrous iron. Biochim Biophys Acta 2015; 1847:717-28. [PMID: 25896560 DOI: 10.1016/j.bbabio.2015.04.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 04/07/2015] [Accepted: 04/12/2015] [Indexed: 10/23/2022]
Abstract
The extremely acidophilic archaeon Ferroplasma acidiphilum is found in iron-rich biomining environments and is an important micro-organism in naturally occurring microbial communities in acid mine drainage. F. acidiphilum is an iron oxidizer that belongs to the order Thermoplasmatales (Euryarchaeota), which harbors the most extremely acidophilic micro-organisms known so far. At present, little is known about the nature or the structural and functional organization of the proteins in F. acidiphilum that impact the iron biogeochemical cycle. We combine here biochemical and biophysical techniques such as enzyme purification, activity measurements, proteomics and spectroscopy to characterize the iron oxidation pathway(s) in F. acidiphilum. We isolated two respiratory membrane protein complexes: a 850 kDa complex containing an aa3-type cytochrome oxidase and a blue copper protein, which directly oxidizes ferrous iron and reduces molecular oxygen, and a 150 kDa cytochrome ba complex likely composed of a di-heme cytochrome and a Rieske protein. We tentatively propose that both of these complexes are involved in iron oxidation respiratory chains, functioning in the so-called uphill and downhill electron flow pathways, consistent with autotrophic life. The cytochrome ba complex could possibly play a role in regenerating reducing equivalents by a reverse ('uphill') electron flow. This study constitutes the first detailed biochemical investigation of the metalloproteins that are potentially directly involved in iron-mediated energy conservation in a member of the acidophilic archaea of the genus Ferroplasma.
Collapse
Affiliation(s)
- Cindy J Castelle
- CNRS, Aix Marseille Université, BIP UMR 7281, FR 3479, 13402 Marseille, France
| | - Magali Roger
- CNRS, Aix Marseille Université, BIP UMR 7281, FR 3479, 13402 Marseille, France
| | - Marielle Bauzan
- CNRS, Aix Marseille Université, Unité de Fermentation, FR 3479, 13402 Marseille, France
| | - Myriam Brugna
- CNRS, Aix Marseille Université, BIP UMR 7281, FR 3479, 13402 Marseille, France
| | - Sabrina Lignon
- CNRS, Aix Marseille Université, Plate-forme Protéomique MaP IBiSA, FR 3479, 13402 Marseille, France
| | - Manfred Nimtz
- Helmholtz Centre for Infection Research, 7 Inhoffen Strasse, 38124 Braunschweig, Germany
| | - Olga V Golyshina
- Helmholtz Centre for Infection Research, 7 Inhoffen Strasse, 38124 Braunschweig, Germany; School of Biological Sciences, Deiniol Road, LL57 2UW, Bangor, UK
| | | | - Marianne Guiral
- CNRS, Aix Marseille Université, BIP UMR 7281, FR 3479, 13402 Marseille, France.
| |
Collapse
|
8
|
Roger M, Biaso F, Castelle CJ, Bauzan M, Chaspoul F, Lojou E, Sciara G, Caffarri S, Giudici-Orticoni MT, Ilbert M. Spectroscopic characterization of a green copper site in a single-domain cupredoxin. PLoS One 2014; 9:e98941. [PMID: 24932914 PMCID: PMC4059628 DOI: 10.1371/journal.pone.0098941] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 05/09/2014] [Indexed: 12/13/2022] Open
Abstract
Cupredoxins are widespread copper-binding proteins, mainly involved in electron transfer pathways. They display a typical rigid greek key motif consisting of an eight stranded β-sandwich. A fascinating feature of cupredoxins is the natural diversity of their copper center geometry. These geometry variations give rise to drastic changes in their color, such as blue, green, red or purple. Based on several spectroscopic and structural analyses, a connection between the geometry of their copper-binding site and their color has been proposed. However, little is known about the relationship between such diversity of copper center geometry in cupredoxins and possible implications for function. This has been difficult to assess, as only a few naturally occurring green and red copper sites have been described so far. We report herein the spectrocopic characterization of a novel kind of single domain cupredoxin of green color, involved in a respiratory pathway of the acidophilic organism Acidithiobacillus ferrooxidans. Biochemical and spectroscopic characterization coupled to bioinformatics analysis reveal the existence of some unusual features for this novel member of the green cupredoxin sub-family. This protein has the highest redox potential reported to date for a green-type cupredoxin. It has a constrained green copper site insensitive to pH or temperature variations. It is a green-type cupredoxin found for the first time in a respiratory pathway. These unique properties might be explained by a region of unknown function never found in other cupredoxins, and by an unusual length of the loop between the second and the fourth copper ligands. These discoveries will impact our knowledge on non-engineered green copper sites, whose involvement in respiratory chains seems more widespread than initially thought.
Collapse
Affiliation(s)
- Magali Roger
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
| | - Frédéric Biaso
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
| | - Cindy J. Castelle
- Department of Earth and Planetary Science, University of California, Berkeley, California, United States of America
| | - Marielle Bauzan
- Unité de Fermentation, Institut de Microbiologie de la Méditerranée, CNRS-FR 3479, Aix Marseille Université, Marseille, France
| | - Florence Chaspoul
- Unité Chimie Physique, Prévention des Risques et Nuisances Technologiques, Faculté de Pharmacie, CNRS-UMR 7263, Aix-Marseille Université, Marseille, France
| | - Elisabeth Lojou
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
| | - Giuliano Sciara
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
| | - Stefano Caffarri
- Unité de Biologie Végétale et Microbiologie Environnementales, CNRS-UMR 7265, CEA, Aix Marseille Université, Marseille, France
| | - Marie-Thérèse Giudici-Orticoni
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
| | - Marianne Ilbert
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
- * E-mail:
| |
Collapse
|
9
|
Le Laz S, Kpebe A, Bauzan M, Lignon S, Rousset M, Brugna M. A biochemical approach to study the role of the terminal oxidases in aerobic respiration in Shewanella oneidensis MR-1. PLoS One 2014; 9:e86343. [PMID: 24466040 PMCID: PMC3899249 DOI: 10.1371/journal.pone.0086343] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 12/11/2013] [Indexed: 11/19/2022] Open
Abstract
The genome of the facultative anaerobic γ-proteobacterium Shewanella oneidensis MR-1 encodes for three terminal oxidases: a bd-type quinol oxidase and two heme-copper oxidases, a A-type cytochrome c oxidase and a cbb3-type oxidase. In this study, we used a biochemical approach and directly measured oxidase activities coupled to mass-spectrometry analysis to investigate the physiological role of the three terminal oxidases under aerobic and microaerobic conditions. Our data revealed that the cbb3-type oxidase is the major terminal oxidase under aerobic conditions while both cbb3-type and bd-type oxidases are involved in respiration at low-O2 tensions. On the contrary, the low O2-affinity A-type cytochrome c oxidase was not detected in our experimental conditions even under aerobic conditions and would therefore not be required for aerobic respiration in S. oneidensis MR-1. In addition, the deduced amino acid sequence suggests that the A-type cytochrome c oxidase is a ccaa3-type oxidase since an uncommon extra-C terminal domain contains two c-type heme binding motifs. The particularity of the aerobic respiratory pathway and the physiological implication of the presence of a ccaa3-type oxidase in S. oneidensis MR-1 are discussed.
Collapse
Affiliation(s)
- Sébastien Le Laz
- CNRS, Aix-Marseille Université, Laboratoire de Bioénergétique et Ingénierie des Protéines, UMR 7281, IMM, Marseille, France
| | - Arlette Kpebe
- CNRS, Aix-Marseille Université, Laboratoire de Bioénergétique et Ingénierie des Protéines, UMR 7281, IMM, Marseille, France
| | - Marielle Bauzan
- CNRS, Aix-Marseille Université, Unité de fermentation, FR3479, IMM, Marseille, France
| | - Sabrina Lignon
- CNRS, Aix-Marseille Université, Plate-forme Protéomique, FR3479, IMM, MaP IBiSA, Marseille, France
| | - Marc Rousset
- CNRS, Aix-Marseille Université, Laboratoire de Bioénergétique et Ingénierie des Protéines, UMR 7281, IMM, Marseille, France
| | - Myriam Brugna
- CNRS, Aix-Marseille Université, Laboratoire de Bioénergétique et Ingénierie des Protéines, UMR 7281, IMM, Marseille, France
- * E-mail:
| |
Collapse
|
10
|
Lieutaud C, Alric J, Bauzan M, Nitschke W, Schoepp-Cothenet B. Study of the high-potential iron sulfur protein in Halorhodospira halophila confirms that it is distinct from cytochrome c as electron carrier. Proc Natl Acad Sci U S A 2005; 102:3260-5. [PMID: 15728382 PMCID: PMC552902 DOI: 10.1073/pnas.0407768102] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2004] [Accepted: 01/14/2005] [Indexed: 11/18/2022] Open
Abstract
The role of high-potential iron sulfur protein (HiPIP) in donating electrons to the photosynthetic reaction center in the halophilic gamma-proteobacterium Halorhodospira halophila was studied by EPR and time-resolved optical spectroscopy. A tight complex between HiPIP and the reaction center was observed. The EPR spectrum of HiPIP in this complex was drastically different from that of the purified protein and provides an analytical tool for the detection and characterization of the complexed form in samples ranging from whole cells to partially purified protein. The bound HiPIP was identified as iso-HiPIP II. Its Em value at pH 7 in the form bound to the reaction center was approximately 100 mV higher (+140 +/- 20 mV) than that of the purified protein. EPR on oriented samples showed HiPIP II to be bound in a well defined geometry, indicating the presence of specific protein-protein interactions at the docking site. At moderately reducing conditions, the bound HiPIP II donates electrons to the cytochrome subunit bound to the reaction center with a half-time of < or =11 micros. This donation reaction was analyzed by using Marcus's outer-sphere electron-transfer theory and compared with those observed in other HiPIP-containing purple bacteria. The results indicate substantial differences between the HiPIP- and the cytochrome c2-mediated re-reduction of the reaction center.
Collapse
Affiliation(s)
- Clément Lieutaud
- Laboratoire de Bioénergétique et Ingénierie des Protéines, Unité Propre de Recherche 9036, Institut de Biologie Structurale et Microbiologie, Centre National de la Recherche Scientifique, 13402 Marseille Cedex 20, France
| | | | | | | | | |
Collapse
|
11
|
Serin G, Joseph G, Ghisolfi L, Bauzan M, Erard M, Amalric F, Bouvet P. Two RNA-binding domains determine the RNA-binding specificity of nucleolin. J Biol Chem 1997; 272:13109-16. [PMID: 9148924 DOI: 10.1074/jbc.272.20.13109] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Nucleolin is an abundant nucleolar RNA-binding protein that seems to be involved in many aspects of ribosome biogenesis. Nucleolin contains four copies of a consensus RNA-binding domain (CS-RBD) found in several other proteins. In vitro RNA-binding studies previously determined that nucleolin interacts specifically with a short RNA stem-loop structure. Taken individually, none of the four CS-RBDs interacts significantly with the RNA target, but a peptide that contains the first two adjacent CS-RBDs (R12) is sufficient to account for nucleolin RNA-binding specificity and affinity. The full integrity of these two domains is required, since N- or C-terminal deletion abolishes the specific interaction with the RNA. Mutation of conserved amino acids within the RNP-1 sequence of CS-RBD 1 or 2 drastically reduces the interaction with the RNA, whereas mutation of the analogous residues in CS-RBDs 3 and 4 has no effect in the context of the R1234G protein (which corresponds to the C-terminal end of nucleolin). Our results demonstrate that nucleolin RNA-binding specificity is the result of a cooperation between two CS-RBDs (RBDs 1 and 2) and also suggests a direct or indirect involvement of the RNP-1 consensus sequence of both CS-RBDs in the recognition of the RNA target.
Collapse
Affiliation(s)
- G Serin
- Laboratoire de Biologie Moléculaire Eucaryote, Institut de Biologie Cellulaire et de Génétique du CNRS, UPR 9006, 118 route de Narbonne, 31062 Toulouse Cedex, France
| | | | | | | | | | | | | |
Collapse
|
12
|
Barras F, Bortoli-German I, Bauzan M, Rouvier J, Gey C, Heyraud A, Henrissat B. Stereochemistry of the hydrolysis reaction catalyzed by endoglucanase Z from Erwinia chrysanthemi. FEBS Lett 1992; 300:145-8. [PMID: 1563515 DOI: 10.1016/0014-5793(92)80183-h] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Endoglucanase Z from the phytopathogenic bacterium Erwinia chrysanthemi (strain 3937) was purified by affinity chromatography on microcrystalline cellulose Avicel PH101. A kinetic characterization using p-nitrophenyl beta-D-cellobioside and p-nitrophenyl beta-D-lactosde as substrates was conducted: endoglucanase Z exhibited Km values of 3 mM and 7.5 mM and Vm values of 129 and 40 nmol.min-1.mg-1 towards p-nitrophenyl beta-D-cellobioside (kcat = 0.1 s-1) and p-nitrophenyl beta-D-lactoside (kcat = 0.03 s-1), respectively). The hydrolysis of cellotetraitol by endoglucanase Z was followed by HPLC and 1H NMR. Results show that cellobiitol and beta-cellobiose are initially formed, demonstrating that the enzyme is acting by a molecular mechanism retaining the anomeric configuration. This suggests the involvement of a glycosyl-enzyme intermediate.
Collapse
Affiliation(s)
- F Barras
- Laboratoire de Chimie Bactérienne, CNRS, Marseille, France
| | | | | | | | | | | | | |
Collapse
|