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Qin L, Sharpe MA, Garavito RM, Ferguson-Miller S. Conserved lipid-binding sites in membrane proteins: a focus on cytochrome c oxidase. Curr Opin Struct Biol 2007; 17:444-50. [PMID: 17719219 PMCID: PMC2395296 DOI: 10.1016/j.sbi.2007.07.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2007] [Revised: 07/06/2007] [Accepted: 07/09/2007] [Indexed: 11/24/2022]
Abstract
Specific interactions between lipids and membrane proteins have been observed in recent high-resolution crystal structures of membrane proteins. A number of cytochrome oxidase structures were analyzed, along with many amino acid sequences of membrane-spanning regions aligned according to their location in the membrane. The results reveal conservation of lipid-binding sites and of the residues that form them. These studies imply that bound lipids have important roles that are crucial to the assembly, structure, or activity of the protein. Evidence for some of these roles in subunit interactions, membrane insertion, and protein-protein complex formation is reviewed.
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Affiliation(s)
- Ling Qin
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824-1319, USA
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52
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Hattori M, Tanaka Y, Fukai S, Ishitani R, Nureki O. Crystallization and preliminary X-ray diffraction analysis of the full-length Mg2+ transporter MgtE. Acta Crystallogr Sect F Struct Biol Cryst Commun 2007; 63:682-4. [PMID: 17671367 PMCID: PMC2335169 DOI: 10.1107/s1744309107032332] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Accepted: 07/03/2007] [Indexed: 11/10/2022]
Abstract
The MgtE family of Mg(2+) transporters are ubiquitously conserved in all three domains. The genes encoding full-length MgtE from seven different species were cloned. Three of the seven MgtE transporters were overexpressed and purified for use in crystallization trials. Only Thermus thermophilus MgtE was successfully crystallized using the sitting-drop vapour-diffusion method. Selenomethionine-substituted (SeMet) crystals were obtained by cross-microseeding using the native microcrystals. The SeMet crystals diffracted X-rays to 3.5 A resolution using synchrotron radiation and belong to space group C222(1), with unit-cell parameters a = 118.3, b = 134.9, c = 366.2 A. Structure determination is in progress.
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Affiliation(s)
- Motoyuki Hattori
- Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8501, Japan
| | - Yoshiki Tanaka
- Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8501, Japan
| | - Shuya Fukai
- Center for Biological Resources and Informatics, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8501, Japan
| | - Ryuichiro Ishitani
- Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8501, Japan
| | - Osamu Nureki
- Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8501, Japan
- SORST, JST, Honcho, Kawaguchi-shi, Saitama 332-0012, Japan
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53
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Yamashita E, Zhang H, Cramer WA. Structure of the cytochrome b6f complex: quinone analogue inhibitors as ligands of heme cn. J Mol Biol 2007; 370:39-52. [PMID: 17498743 PMCID: PMC1993820 DOI: 10.1016/j.jmb.2007.04.011] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Revised: 04/01/2007] [Accepted: 04/04/2007] [Indexed: 11/24/2022]
Abstract
A native structure of the cytochrome b(6)f complex with improved resolution was obtained from crystals of the complex grown in the presence of divalent cadmium. Two Cd(2+) binding sites with different occupancy were determined: (i) a higher affinity site, Cd1, which bridges His143 of cytochrome f and the acidic residue, Glu75, of cyt b(6); in addition, Cd1 is coordinated by 1-2 H(2)O or 1-2 Cl(-); (ii) a second site, Cd2, of lower affinity for which three identified ligands are Asp58 (subunit IV), Glu3 (PetG subunit) and Glu4 (PetM subunit). Binding sites of quinone analogue inhibitors were sought to map the pathway of transfer of the lipophilic quinone across the b(6)f complex and to define the function of the novel heme c(n). Two sites were found for the chromone ring of the tridecyl-stigmatellin (TDS) quinone analogue inhibitor, one near the p-side [2Fe-2S] cluster. A second TDS site was found on the n-side of the complex facing the quinone exchange cavity as an axial ligand of heme c(n). A similar binding site proximal to heme c(n) was found for the n-side inhibitor, NQNO. Binding of these inhibitors required their addition to the complex before lipid used to facilitate crystallization. The similar binding of NQNO and TDS as axial ligands to heme c(n) implies that this heme utilizes plastoquinone as a natural ligand, thus defining an electron transfer complex consisting of hemes b(n), c(n), and PQ, and the pathway of n-side reduction of the PQ pool. The NQNO binding site explains several effects associated with its inhibitory action: the negative shift in heme c(n) midpoint potential, the increased amplitude of light-induced heme b(n) reduction, and an altered EPR spectrum attributed to interaction between hemes c(n) and b(n). A decreased extent of heme c(n) reduction by reduced ferredoxin in the presence of NQNO allows observation of the heme c(n) Soret band in a chemical difference spectrum.
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Abstract
Crystal structures and their implications for function are described for the energy transducing hetero-oligomeric dimeric cytochrome b6f complex of oxygenic photosynthesis from the thermophilic cyanobacterium, Mastigocladus laminosus, and the green alga, Chlamydomonas reinhardtii. The complex has a cytochrome b core and a central quinone exchange cavity, defined by the two monomers that are very similar to those in the respiratory cytochrome bc1 complex. The pathway of quinol/quinone (Q/QH2) transfer emphasizes the labyrinthine internal structure of the complex, including an 11x12 A portal through which Q/QH2, containing a 45-carbon isoprenoid chain, must pass. Three prosthetic groups are present in the b6f complex that are not found in the related bc1 complex: a chlorophyll (Chl) a, a beta-carotene, and a structurally unique covalently bound heme that does not possess amino acid side chains as axial ligands. It is hypothesized that this heme, exposed to the cavity and a neighboring plastoquinone and close to the positive surface potential of the complex, can function in cyclic electron transport via anionic ferredoxin.
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Affiliation(s)
- William A Cramer
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-2054, USA.
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55
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Abstract
Although the examination of the protein data bank reveals an important backlog in the number of three-dimensional structures of membrane proteins, several recent successes are serving as preludes to what will become a very prosperous decade in this field. Systematic investigations of various factors affecting the stability of membrane proteins, as well as their potential to crystallize three dimensionally, have paved the way for such achievements. The importance of the role of detergents both at the level of purification and crystallization is now well established. In addition, the recognition of the protein-detergent complex as the entity to crystallize, as well as the understanding of its physical-chemical properties and discovery of factors affecting these, have permitted the design of better crystallization strategies. As a consequence of the various efforts in the field, new crystallization methods for membrane proteins are being implemented. These have already been successful and are expected to contribute significantly to the future successes. This chapter will review some basic principles in membrane protein crystallization and give an overview of the current state of the art in the field. Some practical guidelines to help the novice approach the problem of membrane protein crystallization from the initial step of protein purification to crystallogenesis will also be given.
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Affiliation(s)
- James Féthière
- European Molecular Biology Laboratory, Heidelberg, Germany
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56
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Structures of the Prokaryotic Mechanosensitive Channels MscL and MscS. CURRENT TOPICS IN MEMBRANES 2007. [DOI: 10.1016/s1063-5823(06)58001-9] [Citation(s) in RCA: 154] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Qin L, Hiser C, Mulichak A, Garavito RM, Ferguson-Miller S. Identification of conserved lipid/detergent-binding sites in a high-resolution structure of the membrane protein cytochrome c oxidase. Proc Natl Acad Sci U S A 2006; 103:16117-22. [PMID: 17050688 PMCID: PMC1616942 DOI: 10.1073/pnas.0606149103] [Citation(s) in RCA: 246] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Well ordered reproducible crystals of cytochrome c oxidase (CcO) from Rhodobacter sphaeroides yield a previously unreported structure at 2.0 A resolution that contains the two catalytic subunits and a number of alkyl chains of lipids and detergents. Comparison with crystal structures of other bacterial and mammalian CcOs reveals that the positions occupied by native membrane lipids and detergent substitutes are highly conserved, along with amino acid residues in their vicinity, suggesting a more prevalent and specific role of lipid in membrane protein structure than often envisioned. Well defined detergent head groups (maltose) are found associated with aromatic residues in a manner similar to phospholipid head groups, likely contributing to the success of alkyl glycoside detergents in supporting membrane protein activity and crystallizability. Other significant features of this structure include the following: finding of a previously unreported crystal contact mediated by cadmium and an engineered histidine tag; documentation of the unique His-Tyr covalent linkage close to the active site; remarkable conservation of a chain of waters in one proton pathway (D-path); and discovery of an inhibitory cadmium-binding site at the entrance to another proton path (K-path). These observations provide important insight into CcO structure and mechanism, as well as the significance of bound lipid in membrane proteins.
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Affiliation(s)
- Ling Qin
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824; and
| | - Carrie Hiser
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824; and
| | - Anne Mulichak
- Industrial Macromolecular Crystallography Association–Collaborative Access Team, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439
| | - R. Michael Garavito
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824; and
| | - Shelagh Ferguson-Miller
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824; and
- To whom correspondence should be addressed. E-mail:
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58
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Sanders CR, Sönnichsen F. Solution NMR of membrane proteins: practice and challenges. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2006; 44 Spec No:S24-40. [PMID: 16826539 DOI: 10.1002/mrc.1816] [Citation(s) in RCA: 183] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
This review focuses upon the application of solution NMR methods to multispan integral membrane proteins, particularly with respect to determination of global folds by this approach. Practical methods are described along with the special difficulties that confront the application of solution NMR to proteins that dwell in the netherworld of the lipid bilayer.
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Affiliation(s)
- Charles R Sanders
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University, Nashville, TN, 37232-8725, USA.
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59
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Zhang H, Cramer WA. Problems in obtaining diffraction-quality crystals of hetero-oligomeric integral membrane proteins. ACTA ACUST UNITED AC 2006; 6:219-23. [PMID: 16211522 DOI: 10.1007/s10969-005-1912-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2004] [Accepted: 01/16/2005] [Indexed: 11/28/2022]
Abstract
The major barrier responsible for the slow pace of structure determination of integral membrane proteins is the difficulty of crystallizing detergent-solubilized hydrophobic proteins, particularly hetero-oligomeric integral membrane proteins. For the latter class of multi-subunit proteins, we have encountered the following problems in addition to the ubiquitous problem of detergent compatibility: (i) instability caused by over-purification that results in delipidation; (ii) protease activity degrading exposed loops and termini of subunits of the complex that could not be inhibited; (iii) poor protein-protein contacts presumably arising from masking by the detergent micelle. Problem (i) could be ameliorated in crystallization of the cytochrome b(6)f complex by augmenting the delipidated complex with synthetic lipid. Problem (ii) has not been solved. Problem (iii) has been solved in other systems by the use of monoclonal antibodies (or other protein ligands) to increase the probability of protein-protein contacts. In the case of the complex formed by the cobalamin and colicin receptor, BtuB, and the receptor binding domain of colicin E3, the latter served as a ligand for protein-protein contacts that facilitated crystallization.
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Affiliation(s)
- Huamin Zhang
- Department of Biological Sciences, Lilly Hall of Life Sciences, Purdue University, West Lafayette, IN 47907-2054, USA.
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60
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Cramer WA, Zhang H. Consequences of the structure of the cytochrome b6f complex for its charge transfer pathways. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:339-45. [PMID: 16787635 DOI: 10.1016/j.bbabio.2006.04.020] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2006] [Revised: 03/30/2006] [Accepted: 04/24/2006] [Indexed: 11/17/2022]
Abstract
At least two features of the crystal structures of the cytochrome b6f complex from the thermophilic cyanobacterium, Mastigocladus laminosus and a green alga, Chlamydomonas reinhardtii, have implications for the pathways and mechanism of charge (electron/proton) transfer in the complex: (i) The narrow 11 x 12 A portal between the p-side of the quinone exchange cavity and p-side plastoquinone/quinol binding niche, through which all Q/QH2 must pass, is smaller in the b6f than in the bc1 complex because of its partial occlusion by the phytyl chain of the one bound chlorophyll a molecule in the b6f complex. Thus, the pathway for trans-membrane passage of the lipophilic quinone is even more labyrinthine in the b6f than in the bc1 complex. (ii) A unique covalently bound heme, heme cn, in close proximity to the n-side b heme, is present in the b6f complex. The b6f structure implies that a Q cycle mechanism must be modified to include heme cn as an intermediate between heme bn and plastoquinone bound at a different site than in the bc1 complex. In addition, it is likely that the heme bn-cn couple participates in photosytem I-linked cyclic electron transport that requires ferredoxin and the ferredoxin: NADP+ reductase. This pathway through the n-side of the b6f complex could overlap with the n-side of the Q cycle pathway. Thus, either regulation is required at the level of the redox state of the hemes that would allow them to be shared by the two pathways, and/or the two different pathways are segregated in the membrane.
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Affiliation(s)
- William A Cramer
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA.
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61
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Guan L, Smirnova IN, Verner G, Nagamori S, Kaback HR. Manipulating phospholipids for crystallization of a membrane transport protein. Proc Natl Acad Sci U S A 2006; 103:1723-6. [PMID: 16446422 PMCID: PMC1413674 DOI: 10.1073/pnas.0510922103] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Crystallization is a major bottleneck to obtaining x-ray structures of membrane proteins. By applying an established crystallization protocol for the lactose permease (LacY) of Escherichia coli, a systematic study of the effect of phospholipids (PL) on crystallization of LacY was undertaken. We observe three different crystal forms that diffract to increasingly better resolution in a manner that correlates with the concentration of copurified PL. Consistently, progressive addition of E. coli PL to delipidated LacY leads to different crystal forms. Tetragonal crystals are obtained with improved diffraction quality for a stable mutant by carefully adjusting PL content. Furthermore, crystals of good quality from wild-type LacY, a particularly difficult protein, were also obtained by using same approach. Thus, it is likely that manipulation of PL is a good strategy for predominantly hydrophobic membrane proteins like LacY.
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Affiliation(s)
| | | | | | | | - H. Ronald Kaback
- Departments of *Physiology, and
- Microbiology, Immunology, and Molecular Genetics, and
- Molecular Biology Institute, University of California, Los Angeles, CA 90095-1662
- To whom correspondence should be addressed at:
675 Charles East Young Drive South, 6720 Macdonald Research Laboratories, Los Angeles, CA 90095-7327. E-mail:
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62
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Yan J, Kurisu G, Cramer WA. Intraprotein transfer of the quinone analogue inhibitor 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone in the cytochrome b6f complex. Proc Natl Acad Sci U S A 2005; 103:69-74. [PMID: 16371475 PMCID: PMC1324977 DOI: 10.1073/pnas.0504909102] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Details are presented of the structural analysis of the cytochrome b(6)f complex from the thermophilic cyanobacterium, Mastigocladus laminosus, in the presence of the electrochemically positive (p)-side quinone analogue inhibitor, 2,5-dibromo-3-methyl-6-isopropylbenzoquinone (DBMIB). One DBMIB binding site was found. This site is peripheral to the quinone binding space defined by the binding sites of other p-side inhibitors previously resolved in cytochrome bc(1)/b(6)f complexes. This high-affinity site resides in a p-side interfacial niche bounded by cytochrome f, subunit IV, and cytochrome b(6), is close (8 A) to the p-side heme b, but distant (19 A) from the [2Fe-2S] cluster. No significant electron density associated with the DBMIB was found elsewhere in the structure. However, the site at which DBMIB can inhibit light-induced redox turnover is within a few A of the [2Fe-2S] cluster, as shown by the absence of inhibition in mutants of Synechococcus sp. PCC 7002 at iron sulfur protein-Leu-111 near the cluster. The ability of a minimum amount of initially oxidized DBMIB to inhibit turnover of WT complex after a second light flash implies that there is a light-activated movement of DBMIB from the distal peripheral site to an inhibitory site proximal to the [2Fe-2S] cluster. Together with the necessary passage of quinone/quinol through the small Q(p) portal in the complex, it is seen that transmembrane traffic of quinone-like molecules through the core of cytochrome bc complexes can be labyrinthine.
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Affiliation(s)
- Jiusheng Yan
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
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63
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Binding sites of lipophilic quinone and quinone analogue inhibitors in the cytochrome b6f complex of oxygenic photosynthesis. Biochem Soc Trans 2005. [DOI: 10.1042/bst0330921] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The main structural features of the cytochrome b6f complex, solved to 3.0–3.1 Å (1 Å=10−10 m) in the cyanobacterium Mastigocladus laminosus and the green alga Chlamydomonas reinhardtii are discussed. The discussion is focused on the binding sites of plastoquinone and quinone analogue inhibitors discerned in the structure. These sites mark the pathway(s) of quinone translocation across the complex.
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64
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Kim H, Dashdorj N, Zhang H, Yan J, Cramer WA, Savikhin S. An anomalous distance dependence of intraprotein chlorophyll-carotenoid triplet energy transfer. Biophys J 2005; 89:L28-30. [PMID: 16055550 PMCID: PMC1366788 DOI: 10.1529/biophysj.105.069609] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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65
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Katsaras J, Harroun TA, Pencer J, Nieh MP. “Bicellar” Lipid Mixtures as used in Biochemical and Biophysical Studies. Naturwissenschaften 2005; 92:355-66. [PMID: 16021408 DOI: 10.1007/s00114-005-0641-1] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Over the past decade "bicellar" lipid mixtures composed of the long-chain dimyristoyl phosphatidylcholine (DMPC) and the short-chain dihexanoyl PC (DHPC) molecules have emerged as a powerful medium for studying membrane associated, biologically relevant macromolecules and assemblies. Depending on temperature, lipid concentration and composition these lipid mixtures can assume a variety of morphologies, some of them alignable in the presence of a magnetic field. This article will examine the biophysical studies that have elucidated the various morphologies assumed by these lipid mixtures, and their use in the biochemical studies of biomolecules.
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Affiliation(s)
- John Katsaras
- National Research Council, Chalk River Laboratories, Chalk River, Ontario, Canada.
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66
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Reyes CL, Chang G. Lipopolysaccharide stabilizes the crystal packing of the ABC transporter MsbA. Acta Crystallogr Sect F Struct Biol Cryst Commun 2005; 61:655-8. [PMID: 16511120 PMCID: PMC1952464 DOI: 10.1107/s1744309105016969] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Accepted: 05/27/2005] [Indexed: 11/10/2022]
Abstract
The ABC transporter MsbA is an integral membrane protein involved in the transport of lipid A and lipopolysaccharides to the outer leaflet of the inner membrane in bacteria. Here, the critical role of the natural substrate lipopolysaccharide in the crystallization and diffraction quality of MsbA crystals is reported. Initial crystals grown in complex with ATP-vanadate alone diffracted to approximately 9 A. Screening of the natural substrate lipopolysaccharides led to the crystallization of MsbA in complex with ADP-vanadate and Ra lipopolysaccharide. The increased order within the crystal lattice allowed structure determination to 4.2 A.
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Affiliation(s)
- Christopher L. Reyes
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road CB105, La Jolla, CA 92137, USA
| | - Geoffrey Chang
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road CB105, La Jolla, CA 92137, USA
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67
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Dashdorj N, Zhang H, Kim H, Yan J, Cramer WA, Savikhin S. The single chlorophyll a molecule in the cytochrome b6f complex: unusual optical properties protect the complex against singlet oxygen. Biophys J 2005; 88:4178-87. [PMID: 15778449 PMCID: PMC1305648 DOI: 10.1529/biophysj.104.058693] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2004] [Accepted: 03/16/2005] [Indexed: 11/18/2022] Open
Abstract
The cytochrome b(6)f complex of oxygenic photosynthesis mediates electron transfer between the reaction centers of photosystems I and II and facilitates coupled proton translocation across the membrane. High-resolution x-ray crystallographic structures (Kurisu et al., 2003; Stroebel et al., 2003) of the cytochrome b(6)f complex unambiguously show that a Chl a molecule is an intrinsic component of the cytochrome b(6)f complex. Although the functional role of this Chl a is presently unclear (Kuhlbrandt, 2003), an excited Chl a molecule is known to produce toxic singlet oxygen as the result of energy transfer from the excited triplet state of the Chl a to oxygen molecules. To prevent singlet oxygen formation in light-harvesting complexes, a carotenoid is typically positioned within approximately 4 A of the Chl a molecule, effectively quenching the triplet excited state of the Chl a. However, in the cytochrome b(6)f complex, the beta-carotene is too far (> or =14 Angstroms) from the Chl a for effective quenching of the Chl a triplet excited state. In this study, we propose that in this complex, the protection is at least partly realized through special arrangement of the local protein structure, which shortens the singlet excited state lifetime of the Chl a by a factor of 20-25 and thus significantly reduces the formation of the Chl a triplet state. Based on optical ultrafast absorption difference experiments and structure-based calculations, it is proposed that the Chl a singlet excited state lifetime is shortened due to electron exchange transfer with the nearby tyrosine residue. To our knowledge, this kind of protection mechanism against singlet oxygen has not yet been reported for any other chlorophyll-containing protein complex. It is also reported that the Chl a molecule in the cytochrome b(6)f complex does not change orientation in its excited state.
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68
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Venzke D, Domgall I, Köcher T, Féthière J, Fischer S, Böttcher B. Elucidation of the Stator Organization in the V-ATPase of Neurospora crassa. J Mol Biol 2005; 349:659-69. [PMID: 15890365 DOI: 10.1016/j.jmb.2005.04.033] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2005] [Revised: 04/13/2005] [Accepted: 04/15/2005] [Indexed: 11/27/2022]
Abstract
V-ATPases are membrane protein complexes that pump protons in the lumen of various subcellular compartments at the expense of ATP. Proton pumping is done by a rotary mechanism that requires a static connection between the membrane pumping domain (V(0)) and the extrinsic catalytic head (V(1)). This static connection is composed of several known subunits of the V-ATPase, but their location and topological relationships are still a matter of controversy. Here, we propose a model for the V-ATPase of Neurospora crassa on the basis of single-particle analysis by electron microscopy. Comparison of the resulting map to that of the A-ATPase from Thermus thermophilus allows the positioning of two subunits in the static connecting region that are unique to eukaryotic V-ATPases (C and H). These two subunits seem to be located on opposite sides of a semicircular arrangement of the peripheral connecting elements, suggesting a role in stabilizing the stator in V-ATPases.
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Affiliation(s)
- David Venzke
- EMBL-Heidelberg Meyerhofstrasse 1, 69117 Heidelberg, Germany
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69
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Berger BW, García RY, Lenhoff AM, Kaler EW, Robinson CR. Relating surfactant properties to activity and solubilization of the human adenosine a3 receptor. Biophys J 2005; 89:452-64. [PMID: 15849244 PMCID: PMC1366546 DOI: 10.1529/biophysj.104.051417] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The effects of various surfactants on the activity and stability of the human adenosine A3 receptor (A3) were investigated. The receptor was expressed using stably transfected HEK293 cells at a concentration of 44 pmol functional receptor per milligram membrane protein and purified using over 50 different nonionic surfactants. A strong correlation was observed between a surfactant's ability to remove A3 from the membrane and the ability of the surfactant to remove A3 selectively relative to other membrane proteins. The activity of A3 once purified also correlates well with the selectivity of the surfactant used. The effects of varying the surfactant were much stronger than those achieved by including A3 ligands in the purification scheme. Notably, all surfactants that gave high efficiency, selectivity and activity fall within a narrow range of hydrophile-lipophile balance values. This effect may reflect the ability of the surfactant to pack effectively at the hydrophobic transmembrane interface. These findings emphasize the importance of identifying appropriate surfactants for a particular membrane protein, and offer promise for the development of rapid, efficient, and systematic methods to facilitate membrane protein purification.
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Affiliation(s)
- Bryan W Berger
- Department of Chemical Engineering, University of Delaware, Newark, Delaware 19716, USA
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Cohen E, Goldshleger R, Shainskaya A, Tal DM, Ebel C, le Maire M, Karlish SJD. Purification of Na+,K+-ATPase Expressed in Pichia pastoris Reveals an Essential Role of Phospholipid-Protein Interactions. J Biol Chem 2005; 280:16610-8. [PMID: 15708860 DOI: 10.1074/jbc.m414290200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Na+,K+-ATPase (porcine alpha/his10-beta) has been expressed in Pichia Pastoris, solubilized in n-dodecyl-beta-maltoside and purified to 70-80% purity by nickel-nitrilotriacetic acid chromatography combined with size exclusion chromatography. The recombinant protein is inactive if the purification is done without added phospholipids. The neutral phospholipid, dioleoylphosphatidylcholine, preserves Na+,K+-ATPase activity of protein prepared in a Na+-containing medium, but activity is lost in a K+-containing medium. By contrast, the acid phospholipid, dioleoylphosphatidylserine, preserves activity in either Na+- or K+-containing media. In optimal conditions activity is preserved for about 2 weeks at 0 degrees C. Both recombinant Na+,K+-ATPase and native pig kidney Na+,K+-ATPase, dissolved in n-dodecyl-beta-maltoside, appear to be mainly stable monomers (alpha/beta) as judged by size exclusion chromatography and sedimentation velocity. Na+,K+-ATPase activities at 37 degrees C of the size exclusion chromatography-purified recombinant and renal Na+,K+-ATPase are comparable but are lower than that of membrane-bound renal Na+,K+-ATPase. The beta subunit is expressed in Pichia Pastoris as two lightly glycosylated polypeptides and is quantitatively deglycosylated by endoglycosidase-H at 0 degrees C, to a single polypeptide. Deglycosylation inactivates Na+,K+-ATPase prepared with dioleoylphosphatidylcholine, whereas dioleoylphosphatidylserine protects after deglycosylation, and Na+,K+-ATPase activity is preserved. This work demonstrates an essential role of phospholipid interactions with Na+,K+-ATPase, including a direct interaction of dioleoylphosphatidylserine, and possibly another interaction of either the neutral or acid phospholipid. Additional lipid effects are likely. A role for the beta subunit in stabilizing conformations of Na+,K+-ATPase (or H+,K+-ATPase) with occluded K+ ions can also be inferred. Purified recombinant Na+,K+-ATPase could become an important experimental tool for various purposes, including, hopefully, structural work.
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Affiliation(s)
- Eytan Cohen
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovoth, Israel
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71
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Li B, Mao D, Liu Y, Li L, Kuang T. Characterization of the cytochrome b(6)f complex from marine green alga, Bryopsis corticulans. PHOTOSYNTHESIS RESEARCH 2005; 83:297-305. [PMID: 16143919 DOI: 10.1007/s11120-004-6555-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2004] [Accepted: 11/22/2004] [Indexed: 05/04/2023]
Abstract
A pure, active cytochrome b(6)f was isolated from the chloroplasts of the marine green alga, Bryopsis corticulans. To investigate and characterize this cytochrome b(6)f complex, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), absorption spectra measurement and HPLC were employed. It was shown that this purified complex contained four large subunits with apparent molecular masses of 34.8, 24, 18.7 and 16.7 kD. The ratio of Cyt (6) to Cyt f was 2.01 : 1. The cytochrome b(6) f was shown to catalyze the transfer of 73 electrons from decylplastoquinol to plastocyanin-ferricyanide per Cyt f per second. alpha-Carotene, one kind of carotenoid that has not been found to present in cytochrome b(6)f complex, was discovered in this preparation by reversed phase HPLC. It was different from beta-carotene usually found in cytochrome b(6)f complex. The configuration of the major alpha-carotene component was assigned to be 9-cis by resonance Raman spectroscopy. Different from the previous reports, the configuration of this alpha-carotene in dissociated state was determined to be all-trans. Besides this carotene, chlorophyll a was also found in this complex. It was shown that the molecular ratios of chlorophyll a, cis and all-trans-alpha-carotene to Cyt f in this complex were 1.2, 0.7 and 0.2, respectively.
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Affiliation(s)
- Binxing Li
- Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing.
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72
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Cramer WA, Yan J, Zhang H, Kurisu G, Smith JL. Structure of the cytochrome b6f complex: new prosthetic groups, Q-space, and the 'hors d'oeuvres hypothesis' for assembly of the complex. PHOTOSYNTHESIS RESEARCH 2005; 85:133-43. [PMID: 15977064 DOI: 10.1007/s11120-004-2149-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2004] [Accepted: 08/13/2004] [Indexed: 05/03/2023]
Abstract
3-A crystal structures of the cytochrome b6f complex have provided a structural framework for the photosynthetic electron transport chain. The structures of the 220,000 molecular weight dimeric cytochrome b6f complex from the thermophilic cyanobacterium, Mastigocladis laminosus (Kurisu et al. 2003, Science 302: 1009-1014), and the green alga, Chlamydomonas reinhardtii (Stroebel et al. 2003, Nature 426: 413-418), are very similar. The latter is the first structure of a integral membrane photosynthetic electron transport complex from a eukaryotic source. The M. laminosus and C. reinhardtii structures have provided structural information and experimental insights to the properties and functions of three native and novel prosthetic groups, a chlorophyll a, a beta-carotene, and a unique heme x, one copy of which is found in each monomer of the cytochrome b6f complex, but not the cytochrome bc1 complex from the mitochondrial respiratory chain of animals and yeast. Several functional insights have emerged from the structures including the function of the dimer; the properties of heme x; the function of the inter-monomer quinone-exchange cavity; a quinone diffusion pathway through relatively narrow crevices or portals; a modified reaction scheme for n-side quinone redox reactions; a necessarily novel mechanism for quenching of the bound chlorophyll triplet state; a possible role for the bound chlorophyll a in activation of the LHC kinase; and a structural and assembly role for the four small PetG, L, M, and N subunits. An 'hors d'oeuvres hypothesis' for assembly of the complex is proposed for the small 'hydrophobic stick' or 'picket fence' polypeptides at the periphery of the complex, based on the cis-positive orientation of the small hydrophobic subunits and the 'toothpick' binding mode of the beta-carotene.
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Affiliation(s)
- William A Cramer
- Department of Biological Sciences, Lilly Hall of Life Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907-2054, USA
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73
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daCosta CJB, Kaiser DEE, Baenziger JE. Role of glycosylation and membrane environment in nicotinic acetylcholine receptor stability. Biophys J 2004; 88:1755-64. [PMID: 15626708 PMCID: PMC1305231 DOI: 10.1529/biophysj.104.052944] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The effects of glycosylation and membrane environment on the structural stability of the nicotinic acetylcholine receptor (nAChR) from Torpedo have been investigated to improve our understanding of factors that influence eukaryotic membrane protein crystallization. Gel shift assays and carbohydrate-specific staining show that the deglycosylation enzyme, Endo F1, removes at least 50% of membrane-reconstituted nAChR glycosylation. The extent of deglycosylation with Endo F1 increases upon detergent solubilization. Removal of between 60-100% of high mannose moieties from the nAChR has no effect on nAChR secondary structure, stability, or flexibility. Deglycosylation does not influence either agonist binding or the ability of the nAChR to undergo agonist-induced conformational change. In contrast, nAChR structural stability, flexibility, and function are all negatively influenced by simple changes in reconstituted membrane lipid composition. Our results suggest that deglycosylation may represent a feasible approach for enhancing the crystallizability of the nAChR. Our data also demonstrate that the dependence of nAChR structural stability on lipid environment may represent a significant obstacle to nAChR crystallization. Some membrane proteins may have evolved complex interactions with their lipid environments. Understanding the complexity of these interactions may be essential for devising an appropriate strategy for the crystallization of some membrane proteins.
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Affiliation(s)
- Corrie J B daCosta
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, 451 Smyth Rd., Ottawa, Ontario, ON K1H 8M5, Canada
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74
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Palsdottir H, Hunte C. Lipids in membrane protein structures. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2004; 1666:2-18. [PMID: 15519305 DOI: 10.1016/j.bbamem.2004.06.012] [Citation(s) in RCA: 319] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2004] [Revised: 06/11/2004] [Accepted: 06/23/2004] [Indexed: 10/26/2022]
Abstract
This review describes the recent knowledge about tightly bound lipids in membrane protein structures and deduces general principles of the binding interactions. Bound lipids are grouped in annular, nonannular, and integral protein lipids. The importance of lipid binding for vertical positioning and tight integration of proteins in the membrane, for assembly and stabilization of oligomeric and multisubunit complexes, for supercomplexes, as well as their functional roles are pointed out. Lipid binding is stabilized by multiple noncovalent interactions from protein residues to lipid head groups and hydrophobic tails. Based on analysis of lipids with refined head groups in membrane protein structures, distinct motifs were identified for stabilizing interactions between the phosphodiester moieties and side chains of amino acid residues. Differences between binding at the electropositive and electronegative membrane side, as well as a preferential binding to the latter, are observed. A first attempt to identify lipid head group specific binding motifs is made. A newly identified cardiolipin binding site in the yeast cytochrome bc(1) complex is described. Assignment of unsaturated lipid chains and evolutionary aspects of lipid binding are discussed.
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Affiliation(s)
- Hildur Palsdottir
- Department of Molecular Membrane Biology, Max-Planck-Institute of Biophysics, Marie-Curie-Strasse 15, D-60439 Frankfurt, Germany
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75
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Nollert P. Membrane protein crystallization in amphiphile phases: practical and theoretical considerations. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2004; 88:339-57. [PMID: 15652249 PMCID: PMC2748814 DOI: 10.1016/j.pbiomolbio.2004.07.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Integral membrane proteins are amphiphilic molecules. In order to enable chromatographic purification and crystallization, a complementary amphiphilic microenvironment must be created and maintained. Various types of amphiphilic phases have been employed in crystallizations and intricate amphiphilic microenvironmental structures have resulted from these and are found inside membrane protein crystals. In this review the process of crystallization is put into the context of amphiphile phase transitions. Finally, practical factors are considered and a pragmatic way is suggested to pursue membrane protein crystallization trials.
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Affiliation(s)
- Peter Nollert
- deCODE BioStructures, 7869 NE Day Rd. W, Bainbridge Island, WA 98110, USA.
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76
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Abstract
The bc1 complexes are intrinsic membrane proteins that catalyze the oxidation of ubihydroquinone and the reduction of cytochrome c in mitochondrial respiratory chains and bacterial photosynthetic and respiratory chains. The bc1 complex operates through a Q-cycle mechanism that couples electron transfer to generation of the proton gradient that drives ATP synthesis. Genetic defects leading to mutations in proteins of the respiratory chain, including the subunits of the bc1 complex, result in mitochondrial myopathies, many of which are a direct result of dysfunction at catalytic sites. Some myopathies, especially those in the cytochrome b subunit, exacerbate free-radical damage by enhancing superoxide production at the ubihydroquinone oxidation site. This bypass reaction appears to be an unavoidable feature of the reaction mechanism. Cellular aging is largely attributable to damage to DNA and proteins from the reactive oxygen species arising from superoxide and is a major contributing factor in many diseases of old age. An understanding of the mechanism of the bc1 complex is therefore central to our understanding of the aging process. In addition, a wide range of inhibitors that mimic the quinone substrates are finding important applications in clinical therapy and agronomy. Recent structural studies have shown how many of these inhibitors bind, and have provided important clues to the mechanism of action and the basis of resistance through mutation. This paper reviews recent advances in our understanding of the mechanism of the bc1 complex and their relation to these physiologically important issues in the context of the structural information available.
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Affiliation(s)
- Antony R Crofts
- Department of Biochemistry, and Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
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77
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Cramer WA. Ironies in photosynthetic electron transport: a personal perspective. PHOTOSYNTHESIS RESEARCH 2004; 80:293-305. [PMID: 16328827 DOI: 10.1023/b:pres.0000030600.28313.58] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
In this brief personal perspective, studies, mainly in my laboratory, directed toward understanding of the structure and function of the Fe-metalloprotein electron transport carriers of oxygenic photosynthesis are discussed. This level of understanding and the description of the events that led to this level are inevitably incomplete. The Fe-proteins considered are those, cytochromes b-559 (560), f, b (6), and x, and the Rieske [2Fe-2S] iron-sulfur protein, which have now been placed in a structural context as a result of X-ray diffraction analysis of crystals of Photosystem II and the cytochrome b (6) f complex and the Photosystem II reaction center.
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Affiliation(s)
- William A Cramer
- Department of Biological Sciences, Purdue University, Lilly Hall of Life Sciences, 915 West State Street, West Lafayette, IN, 47906-2054, USA,
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78
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Darrouzet E, Cooley JW, Daldal F. The Cytochrome bc (1) Complex and its Homologue the b (6) f Complex: Similarities and Differences. PHOTOSYNTHESIS RESEARCH 2004; 79:25-44. [PMID: 16228398 DOI: 10.1023/b:pres.0000011926.47778.4e] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The ubihydroquinone:cytochrome c oxidoreductase (also called complex III, or bc (1) complex), is a multi subunit enzyme encountered in a very broad variety of organisms including uni- and multi-cellular eukaryotes, plants (in their mitochondria) and bacteria. Most bacteria and mitochondria harbor various forms of the bc (1) complex, while plant and algal chloroplasts as well as cyanobacteria contain a homologous protein complex called plastohydroquinone:plastocyanin oxidoreductase or b (6) f complex. Together, these enzyme complexes constitute the superfamily of the bc complexes. Depending on the physiology of the organisms, they often play critical roles in respiratory and photosynthetic electron transfer events, and always contribute to the generation of the proton motive force subsequently used by the ATP synthase. Primarily, this review is focused on comparing the 'mitochondrial-type' bc (1) complex and the 'chloroplast-type' b (6) f complex both in terms of structure and function. Specifically, subunit composition, cofactor content and assembly, inhibitor sensitivity, proton pumping, concerted electron transfer and Fe-S subunit large-scale domain movement of these complexes are discussed. This is a timely undertaking in light of the structural information that is emerging for the b (6) f complex.
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79
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Stroebel D, Choquet Y, Popot JL, Picot D. An atypical haem in the cytochrome b6f complex. Nature 2003; 426:413-8. [PMID: 14647374 DOI: 10.1038/nature02155] [Citation(s) in RCA: 534] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2003] [Accepted: 10/28/2003] [Indexed: 11/09/2022]
Abstract
Photosystems I and II (PSI and II) are reaction centres that capture light energy in order to drive oxygenic photosynthesis; however, they can only do so by interacting with the multisubunit cytochrome b(6)f complex. This complex receives electrons from PSII and passes them to PSI, pumping protons across the membrane and powering the Q-cycle. Unlike the mitochondrial and bacterial homologue cytochrome bc(1), cytochrome b(6)f can switch to a cyclic mode of electron transfer around PSI using an unknown pathway. Here we present the X-ray structure at 3.1 A of cytochrome b(6)f from the alga Chlamydomonas reinhardtii. The structure bears similarities to cytochrome bc(1) but also exhibits some unique features, such as binding chlorophyll, beta-carotene and an unexpected haem sharing a quinone site. This haem is atypical as it is covalently bound by one thioether linkage and has no axial amino acid ligand. This haem may be the missing link in oxygenic photosynthesis.
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Affiliation(s)
- David Stroebel
- Laboratoire de Physico-Chimie Moléculaire des Membranes Biologiques, CNRS/Université Paris 7, UMR 7099, France
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80
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81
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Kurisu G, Zhang H, Smith JL, Cramer WA. Structure of the cytochrome b6f complex of oxygenic photosynthesis: tuning the cavity. Science 2003; 302:1009-14. [PMID: 14526088 DOI: 10.1126/science.1090165] [Citation(s) in RCA: 497] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The cytochrome b6f complex provides the electronic connection between the photosystem I and photosystem II reaction centers of oxygenic photosynthesis and generates a transmembrane electrochemical proton gradient for adenosine triphosphate synthesis. A 3.0 angstrom crystal structure of the dimeric b6f complex from the thermophilic cyanobacterium Mastigocladus laminosus reveals a large quinone exchange cavity, stabilized by lipid, in which plastoquinone, a quinone-analog inhibitor, and a novel heme are bound. The core of the b6f complex is similar to the analogous respiratory cytochrome bc1 complex, but the domain arrangement outside the core and the complement of prosthetic groups are strikingly different. The motion of the Rieske iron-sulfur protein extrinsic domain, essential for electron transfer, must also be different in the b6f complex.
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Affiliation(s)
- Genji Kurisu
- Department of Biological Sciences, 915 West State Street, Purdue University, West Lafayette, IN 47907-2054, USA
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82
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Abstract
Currently, relatively few proteomics studies of chloroplast have been published, but the field has just started emerging and is likely to develop more rapidly in the future. While the complex membrane structure of the chloroplast makes it difficult to study its entire proteome by global approaches, proteomics has considerably increased our knowledge of the proteins of single compartments such as, for instance, the envelope and the thylakoid lumen. Proteomics has also succeeded in the subunit characterisation of select protein complexes such as the ribosomes and the cytochrome b (6)f complex. In addition, proteomics was successfully applied to find new potential target pathways for thioredoxin-mediated signal transduction. In this review, we present an overview of the latest developments in the field of chloroplast proteomics and discuss their impact on photosynthesis research. In addition, we summarise the current state of research in proteomics of the photosynthetic cyanobactrium Synechocystis sp. PCC 6803.
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Affiliation(s)
- Wolfgang P Schröder
- Departments of Chemistry and Biochemistry, Umeå University, 901 87, Umeå, Sweden
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