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Christoffer C, Harini K, Archit G, Kihara D. Assembly of Protein Complexes in and on the Membrane with Predicted Spatial Arrangement Constraints. J Mol Biol 2024; 436:168486. [PMID: 38336197 PMCID: PMC10942765 DOI: 10.1016/j.jmb.2024.168486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 01/17/2024] [Accepted: 02/05/2024] [Indexed: 02/12/2024]
Abstract
Membrane proteins play crucial roles in various cellular processes, and their interactions with other proteins in and on the membrane are essential for their proper functioning. While an increasing number of structures of more membrane proteins are being determined, the available structure data is still sparse. To gain insights into the mechanisms of membrane protein complexes, computational docking methods are necessary due to the challenge of experimental determination. Here, we introduce Mem-LZerD, a rigid-body membrane docking algorithm designed to take advantage of modern membrane modeling and protein docking techniques to facilitate the docking of membrane protein complexes. Mem-LZerD is based on the LZerD protein docking algorithm, which has been constantly among the top servers in many rounds of CAPRI protein docking assessment. By employing a combination of geometric hashing, newly constrained by the predicted membrane height and tilt angle, and model scoring accounting for the energy of membrane insertion, we demonstrate the capability of Mem-LZerD to model diverse membrane protein-protein complexes. Mem-LZerD successfully performed unbound docking on 13 of 21 (61.9%) transmembrane complexes in an established benchmark, more than shown by previous approaches. It was additionally tested on new datasets of 44 transmembrane complexes and 92 peripheral membrane protein complexes, of which it successfully modeled 35 (79.5%) and 15 (16.3%) complexes respectively. When non-blind orientations of peripheral targets were included, the number of successes increased to 54 (58.7%). We further demonstrate that Mem-LZerD produces complex models which are suitable for molecular dynamics simulation. Mem-LZerD is made available at https://lzerd.kiharalab.org.
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Affiliation(s)
- Charles Christoffer
- Department of Computer Science, Purdue University, West Lafayette, IN 47907, USA
| | - Kannan Harini
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India; Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Gupta Archit
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA; Department of Genetic Engineering, SRM Institute of Science and Technology, Kattankulathur 603203, India
| | - Daisuke Kihara
- Department of Computer Science, Purdue University, West Lafayette, IN 47907, USA; Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA; Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.
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2
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Christoffer C, Harini K, Archit G, Kihara D. Assembly of Protein Complexes In and On the Membrane with Predicted Spatial Arrangement Constraints. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.20.563303. [PMID: 37961264 PMCID: PMC10634698 DOI: 10.1101/2023.10.20.563303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Membrane proteins play crucial roles in various cellular processes, and their interactions with other proteins in and on the membrane are essential for their proper functioning. While an increasing number of structures of more membrane proteins are being determined, the available structure data is still sparse. To gain insights into the mechanisms of membrane protein complexes, computational docking methods are necessary due to the challenge of experimental determination. Here, we introduce Mem-LZerD, a rigid-body membrane docking algorithm designed to take advantage of modern membrane modeling and protein docking techniques to facilitate the docking of membrane protein complexes. Mem-LZerD is based on the LZerD protein docking algorithm, which has been constantly among the top servers in many rounds of CAPRI protein docking assessment. By employing a combination of geometric hashing, newly constrained by the predicted membrane height and tilt angle, and model scoring accounting for the energy of membrane insertion, we demonstrate the capability of Mem-LZerD to model diverse membrane protein-protein complexes. Mem-LZerD successfully performed unbound docking on 13 of 21 (61.9%) transmembrane complexes in an established benchmark, more than shown by previous approaches. It was additionally tested on new datasets of 44 transmembrane complexes and 92 peripheral membrane protein complexes, of which it successfully modeled 35 (79.5%) and 15 (16.3%) complexes respectively. When non-blind orientations of peripheral targets were included, the number of successes increased to 54 (58.7%). We further demonstrate that Mem-LZerD produces complex models which are suitable for molecular dynamics simulation. Mem-LZerD is made available at https://lzerd.kiharalab.org.
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Affiliation(s)
- Charles Christoffer
- Department of Computer Science, Purdue University, West Lafayette, IN, 47907, USA
| | - Kannan Harini
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
| | - Gupta Archit
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
- Department of Genetic Engineering, SRM Institute of Science and Technology, Kattankulathur 603203, India
| | - Daisuke Kihara
- Department of Computer Science, Purdue University, West Lafayette, IN, 47907, USA
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
- Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN, 47907, USA
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3
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Grunow AL, Carroll SC, Kreiman AN, Sutherland MC. Structure-function analysis of the heme-binding WWD domain in the bacterial holocytochrome c synthase, CcmFH. mBio 2023; 14:e0150923. [PMID: 37929956 PMCID: PMC10746174 DOI: 10.1128/mbio.01509-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 09/26/2023] [Indexed: 11/07/2023] Open
Abstract
Heme trafficking is a fundamental biological process, yet its direct study has been hampered due to heme's tight intracellular regulation, heme cytotoxicity, and the transient nature of trafficking. The bacterial System I and System II cytochrome c biogenesis pathways are developing into models to interrogate heme trafficking mechanisms, as they function to transport heme from inside to outside the cell for attachment to apocytochrome c. Cytochromes c require heme for folding and to function in the context of electron transport chains for critical cellular functions, such as respiration. We focus on System I, comprised of eight membrane proteins, CcmABCDEFGH, proposed to function in two steps: CcmABCD mediates the transfer of heme and attachment to CcmE. HoloCcmE chaperones heme to CcmFH for attachment to apocytochrome c. While CcmFH is known to be the holocytochrome c synthase, the mechanism of heme interaction and positioning for attachment to apocytochrome c remains to be elucidated. A comprehensive structure-function analysis of the conserved WWD domain in CcmF was undertaken utilizing alanine-scanning and cysteine-scanning, revealing residues critical for CcmF's synthase function and residues required for interaction with the 2- and 4-vinyls of heme. This analysis demonstrates for the first time that the CcmF WWD domain directly interacts with heme and that heme interactions within this domain are required for attachment to apocytochrome c. This in-depth interrogation of heme binding now allows for comparison across cytochrome c biogenesis proteins CcmF, CcmC, and CcsBA, revealing common mechanisms of heme interaction in these heme trafficking pathways.IMPORTANCEHeme is an essential co-factor for proteins involved with critical cellular functions, such as energy production and oxygen transport. Thus, understanding how heme interacts with proteins and is moved through cells is a fundamental biological question. This work studies the System I cytochrome c biogenesis pathway, which in some species (including Escherichia coli) is composed of eight integral membrane or membrane-associated proteins called CcmA-H that are proposed to function in two steps to transport and attach heme to apocytochrome c. Cytochrome c requires this heme attachment to function in electron transport chains to generate cellular energy. A conserved WWD heme-handling domain in CcmFH is analyzed and residues critical for heme interaction and holocytochrome c synthase activity are identified. CcmFH is the third member of the WWD domain-containing heme-handling protein family to undergo a comprehensive structure-function analysis, allowing for comparison of heme interaction across this protein family.
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Affiliation(s)
- Amber L. Grunow
- Department of Biological Sciences, University of Delaware, Newark, Delaware, USA
| | - Susan C. Carroll
- Department of Biological Sciences, University of Delaware, Newark, Delaware, USA
| | - Alicia N. Kreiman
- Department of Biological Sciences, University of Delaware, Newark, Delaware, USA
| | - Molly C. Sutherland
- Department of Biological Sciences, University of Delaware, Newark, Delaware, USA
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4
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Huynh JQ, Lowder EP, Kranz RG. Structural basis of membrane machines that traffick and attach heme to cytochromes. J Biol Chem 2023; 299:105332. [PMID: 37827288 PMCID: PMC10663686 DOI: 10.1016/j.jbc.2023.105332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 10/04/2023] [Accepted: 10/06/2023] [Indexed: 10/14/2023] Open
Abstract
We evaluate cryoEM and crystal structures of two molecular machines that traffick heme and attach it to cytochrome c (cyt c), the second activity performed by a cyt c synthase. These integral membrane proteins, CcsBA and CcmF/H, both covalently attach heme to cyt c, but carry it out via different mechanisms. A CcsB-CcsA complex transports heme through a channel to its external active site, where it forms two thioethers between reduced (Fe+2) heme and CysXxxXxxCysHis in cyt c. The active site is formed by a periplasmic WWD sequence and two histidines (P-His1 and P-His2). We evaluate each proposed functional domain in CcsBA cryoEM densities, exploring their presence in other CcsB-CcsA proteins from a wide distribution of organisms (e.g., from Gram positive to Gram negative bacteria to chloroplasts.) Two conserved pockets, for the first and second cysteines of CXXCH, explain stereochemical heme attachment. In addition to other universal features, a conserved periplasmic beta stranded structure, called the beta cap, protects the active site when external heme is not present. Analysis of CcmF/H, here called an oxidoreductase and cyt c synthase, addresses mechanisms of heme access and attachment. We provide evidence that CcmF/H receives Fe+3 heme from holoCcmE via a periplasmic entry point in CcmF, whereby heme is inserted directly into a conserved WWD/P-His domain from above. Evidence suggests that CcmF acts as a heme reductase, reducing holoCcmE (to Fe+2) through a transmembrane electron transfer conduit, which initiates a complicated series of events at the active site.
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Affiliation(s)
- Jonathan Q Huynh
- Department of Biology, Washington University, St. Louis, Missouri, USA
| | - Ethan P Lowder
- Department of Biology, Washington University, St. Louis, Missouri, USA
| | - Robert G Kranz
- Department of Biology, Washington University, St. Louis, Missouri, USA.
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5
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Li J, Zheng W, Gu M, Han L, Luo Y, Yu K, Sun M, Zong Y, Ma X, Liu B, Lowder EP, Mendez DL, Kranz RG, Zhang K, Zhu J. Structures of the CcmABCD heme release complex at multiple states. Nat Commun 2022; 13:6422. [PMID: 36307425 PMCID: PMC9616876 DOI: 10.1038/s41467-022-34136-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 10/14/2022] [Indexed: 12/25/2022] Open
Abstract
Cytochromes c use heme as a cofactor to carry electrons in respiration and photosynthesis. The cytochrome c maturation system I, consisting of eight membrane proteins (CcmABCDEFGH), results in the attachment of heme to cysteine residues of cytochrome c proteins. Since all c-type cytochromes are periplasmic, heme is first transported to a periplasmic heme chaperone, CcmE. A large membrane complex, CcmABCD has been proposed to carry out this transport and linkage to CcmE, yet the structural basis and mechanisms underlying the process are unknown. We describe high resolution cryo-EM structures of CcmABCD in an unbound form, in complex with inhibitor AMP-PNP, and in complex with ATP and heme. We locate the ATP-binding site in CcmA and the heme-binding site in CcmC. Based on our structures combined with functional studies, we propose a hypothetic model of heme trafficking, heme transfer to CcmE, and ATP-dependent release of holoCcmE from CcmABCD. CcmABCD represents an ABC transporter complex using the energy of ATP hydrolysis for the transfer of heme from one binding partner (CcmC) to another (CcmE).
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Affiliation(s)
- Jiao Li
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China ,grid.47100.320000000419368710Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511 USA
| | - Wan Zheng
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
| | - Ming Gu
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
| | - Long Han
- grid.47100.320000000419368710Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511 USA
| | - Yanmei Luo
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
| | - Koukou Yu
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
| | - Mengxin Sun
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
| | - Yuliang Zong
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
| | - Xiuxiu Ma
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
| | - Bing Liu
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
| | - Ethan P. Lowder
- grid.4367.60000 0001 2355 7002Department of Biology, Washington University in St. Louis, CB 1137, One Brookings Drive, St. Louis, MO 63130-4899 USA
| | - Deanna L. Mendez
- grid.4367.60000 0001 2355 7002Department of Biology, Washington University in St. Louis, CB 1137, One Brookings Drive, St. Louis, MO 63130-4899 USA
| | - Robert G. Kranz
- grid.4367.60000 0001 2355 7002Department of Biology, Washington University in St. Louis, CB 1137, One Brookings Drive, St. Louis, MO 63130-4899 USA
| | - Kai Zhang
- grid.47100.320000000419368710Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511 USA
| | - Jiapeng Zhu
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
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6
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Gao M, Nakajima An D, Parks JM, Skolnick J. AF2Complex predicts direct physical interactions in multimeric proteins with deep learning. Nat Commun 2022; 13:1744. [PMID: 35365655 PMCID: PMC8975832 DOI: 10.1038/s41467-022-29394-2] [Citation(s) in RCA: 103] [Impact Index Per Article: 51.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 03/15/2022] [Indexed: 12/20/2022] Open
Abstract
Accurate descriptions of protein-protein interactions are essential for understanding biological systems. Remarkably accurate atomic structures have been recently computed for individual proteins by AlphaFold2 (AF2). Here, we demonstrate that the same neural network models from AF2 developed for single protein sequences can be adapted to predict the structures of multimeric protein complexes without retraining. In contrast to common approaches, our method, AF2Complex, does not require paired multiple sequence alignments. It achieves higher accuracy than some complex protein-protein docking strategies and provides a significant improvement over AF-Multimer, a development of AlphaFold for multimeric proteins. Moreover, we introduce metrics for predicting direct protein-protein interactions between arbitrary protein pairs and validate AF2Complex on some challenging benchmark sets and the E. coli proteome. Lastly, using the cytochrome c biogenesis system I as an example, we present high-confidence models of three sought-after assemblies formed by eight members of this system. Accurate descriptions of protein-protein interactions are essential for understanding biological systems. Here the authors present AF2Complex and show that application to the E. coli cytochrome biogenesis system I yields confident computational models for three sought-after assemblies.
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Affiliation(s)
- Mu Gao
- Center for the Study of Systems Biology, School of Biological Sciences, Atlanta, GA, USA.
| | - Davi Nakajima An
- School of Computer Science, Georgia Institute of Technology, Atlanta, GA, USA
| | - Jerry M Parks
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Jeffrey Skolnick
- Center for the Study of Systems Biology, School of Biological Sciences, Atlanta, GA, USA.
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7
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Mendez DL, Lowder EP, Tillman DE, Sutherland MC, Collier AL, Rau MJ, Fitzpatrick JA, Kranz RG. Cryo-EM of CcsBA reveals the basis for cytochrome c biogenesis and heme transport. Nat Chem Biol 2022; 18:101-108. [PMID: 34931065 PMCID: PMC8712405 DOI: 10.1038/s41589-021-00935-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 10/22/2021] [Indexed: 01/09/2023]
Abstract
Although the individual structures and respiratory functions of cytochromes are well studied, the structural basis for their assembly, including transport of heme for attachment, are unknown. We describe cryo-electron microscopy (cryo-EM) structures of CcsBA, a bifunctional heme transporter and cytochrome c (cyt c) synthase. Models built from the cryo-EM densities show that CcsBA is trapped with heme in two conformations, herein termed the closed and open states. The closed state has heme located solely at a transmembrane (TM) site, with a large periplasmic domain oriented such that access of heme to the cytochrome acceptor is denied. The open conformation contains two heme moieties, one in the TM-heme site and another in an external site (P-heme site). The presence of heme in the periplasmic site at the base of a chamber induces a large conformational shift that exposes the heme for reaction with apocytochrome c (apocyt c). Consistent with these structures, in vivo and in vitro cyt c synthase studies suggest a mechanism for transfer of the periplasmic heme to cytochrome.
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Affiliation(s)
- Deanna L. Mendez
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Ethan P. Lowder
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Dustin E. Tillman
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Molly C. Sutherland
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Andrea L. Collier
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Michael J. Rau
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - James A.J. Fitzpatrick
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO 63110, USA.,Departments of Cell Biology & Physiology and Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA.,Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Robert G. Kranz
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA,Corresponding author is Robert G. Kranz:
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8
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Sutherland MC, Mendez DL, Babbitt SE, Tillman DE, Melnikov O, Tran NL, Prizant NT, Collier AL, Kranz RG. In vitro reconstitution reveals major differences between human and bacterial cytochrome c synthases. eLife 2021; 10:64891. [PMID: 33973521 PMCID: PMC8112865 DOI: 10.7554/elife.64891] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 03/23/2021] [Indexed: 11/25/2022] Open
Abstract
Cytochromes c are ubiquitous heme proteins in mitochondria and bacteria, all possessing a CXXCH (CysXxxXxxCysHis) motif with covalently attached heme. We describe the first in vitro reconstitution of cytochrome c biogenesis using purified mitochondrial (HCCS) and bacterial (CcsBA) cytochrome c synthases. We employ apocytochrome c and peptide analogs containing CXXCH as substrates, examining recognition determinants, thioether attachment, and subsequent release and folding of cytochrome c. Peptide analogs reveal very different recognition requirements between HCCS and CcsBA. For HCCS, a minimal 16-mer peptide is required, comprised of CXXCH and adjacent alpha helix 1, yet neither thiol is critical for recognition. For bacterial CcsBA, both thiols and histidine are required, but not alpha helix 1. Heme attached peptide analogs are not released from the HCCS active site; thus, folding is important in the release mechanism. Peptide analogs behave as inhibitors of cytochrome c biogenesis, paving the way for targeted control. From tiny bacteria to the tallest trees, most life on Earth carries a protein called cytochrome c, which helps to create the energy that powers up cells. Cytochrome c does so thanks to its heme, a molecule that enables the chemical reactions required for the energy-creating process. Despite both relying on cytochrome c, animals and bacteria differ in the enzyme they use to attach the heme to the cytochrome. Spotting variations in how this ‘cytochrome c synthase’ works would help to find compounds that deactivate the enzyme in bacteria, but not in humans. However, studying cytochrome c synthase in living cells is challenging. To bypass this issue, Sutherland, Mendez, Babbitt et al. successfully reconstituted cytochrome c synthases from humans and bacteria in test tubes. This allowed them to examine in detail which structures the enzymes recognize to spot where to attach the heme onto their target. The experiments revealed that human and bacterial synthases actually rely on different parts of the cytochrome c to orient themselves. Different short compounds could also block either the human or bacterial enzyme. Variations between human and bacterial cytochrome c synthase could lead to new antibiotics which deactivate the cytochrome and kill bacteria while sparing patients. The next step is to identify molecules that specifically interfere with cytochrome c synthase in bacteria, and could be tested in clinical trials.
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Affiliation(s)
- Molly C Sutherland
- Department of Biology, Washington University in St. Louis, St. Louis, United States.,Department of Biological Sciences, University of Delaware, Newark, United States
| | - Deanna L Mendez
- Department of Biology, Washington University in St. Louis, St. Louis, United States
| | - Shalon E Babbitt
- Department of Biology, Washington University in St. Louis, St. Louis, United States
| | - Dustin E Tillman
- Department of Biology, Washington University in St. Louis, St. Louis, United States
| | - Olga Melnikov
- Department of Biology, Washington University in St. Louis, St. Louis, United States
| | - Nathan L Tran
- Department of Biology, Washington University in St. Louis, St. Louis, United States
| | - Noah T Prizant
- Department of Biology, Washington University in St. Louis, St. Louis, United States
| | - Andrea L Collier
- Department of Biology, Washington University in St. Louis, St. Louis, United States
| | - Robert G Kranz
- Department of Biology, Washington University in St. Louis, St. Louis, United States
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9
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Kolli R, Engstler C, Akbaş Ş, Mower JP, Soll J, Carrie C. The OXA2a Insertase of Arabidopsis Is Required for Cytochrome c Maturation. PLANT PHYSIOLOGY 2020; 184:1042-1055. [PMID: 32759271 PMCID: PMC7536658 DOI: 10.1104/pp.19.01248] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 07/28/2020] [Indexed: 06/02/2023]
Abstract
In yeast (Saccharomyces cerevisiae) and human (Homo sapiens) mitochondria, Oxidase assembly protein1 (Oxa1) is the general insertase for protein insertion from the matrix side into the inner membrane while Cytochrome c oxidase assembly protein18 (Cox18/Oxa2) is specifically involved in the topogenesis of the complex IV subunit, Cox2. Arabidopsis (Arabidopsis thaliana) mitochondria contain four OXA homologs: OXA1a, OXA1b, OXA2a, and OXA2b. OXA2a and OXA2b are unique members of the Oxa1 superfamily, in that they possess a tetratricopeptide repeat (TPR) domain at their C termini. Here, we determined the role of OXA2a by studying viable mutant plants generated by partial complementation of homozygous lethal OXA2a transfer-DNA insertional mutants using the developmentally regulated ABSCISIC ACID INSENSITIVE3 (ABI3) promoter. The ABI3p:OXA2a plants displayed growth retardation due to a reduction in the steady-state abundances of both c-type cytochromes, cytochrome c 1 and cytochrome c The observed reduction in the steady-state abundance of complex III could be attributed to cytochrome c 1 being one of its subunits. Expression of a soluble heme lyase from an organism with cytochrome c maturation system III could functionally complement the lack of OXA2a. This implies that OXA2a is required for the system I cytochrome c maturation of Arabidopsis. Due to the interaction of OXA2a with Cytochrome c maturation protein CcmF C-terminal-like protein (CCMFC) in a yeast split-ubiquitin based interaction assay, we propose that OXA2a aids in the membrane insertion of CCMFC, which is presumed to form the heme lyase component of the cytochrome c maturation pathway. In contrast with the crucial role played by the TPR domain of OXA2b, the TPR domain of OXA2a is not essential for its functionality.
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Affiliation(s)
- Renuka Kolli
- Department Biologie I - Botanik, Ludwig-Maximilians-Universität München, Planegg-Martinsried, 82152, Germany
| | - Carina Engstler
- Department Biologie I - Botanik, Ludwig-Maximilians-Universität München, Planegg-Martinsried, 82152, Germany
| | - Şebnem Akbaş
- Department Biologie I - Botanik, Ludwig-Maximilians-Universität München, Planegg-Martinsried, 82152, Germany
| | - Jeffrey P Mower
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska 68588
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska 68583
| | - Jürgen Soll
- Department Biologie I - Botanik, Ludwig-Maximilians-Universität München, Planegg-Martinsried, 82152, Germany
- Munich Centre for Integrated Protein Science, CIPSM, Ludwig-Maximilians-Universität München, Munich, 81377, Germany
| | - Chris Carrie
- Department Biologie I - Botanik, Ludwig-Maximilians-Universität München, Planegg-Martinsried, 82152, Germany
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10
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Abriata LA, Dal Peraro M. State-of-the-art web services for de novo protein structure prediction. Brief Bioinform 2020; 22:5870389. [PMID: 34020540 DOI: 10.1093/bib/bbaa139] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 06/04/2020] [Accepted: 06/05/2020] [Indexed: 02/06/2023] Open
Abstract
Residue coevolution estimations coupled to machine learning methods are revolutionizing the ability of protein structure prediction approaches to model proteins that lack clear homologous templates in the Protein Data Bank (PDB). This has been patent in the last round of the Critical Assessment of Structure Prediction (CASP), which presented several very good models for the hardest targets. Unfortunately, literature reporting on these advances often lacks digests tailored to lay end users; moreover, some of the top-ranking predictors do not provide webservers that can be used by nonexperts. How can then end users benefit from these advances and correctly interpret the predicted models? Here we review the web resources that biologists can use today to take advantage of these state-of-the-art methods in their research, including not only the best de novo modeling servers but also datasets of models precomputed by experts for structurally uncharacterized protein families. We highlight their features, advantages and pitfalls for predicting structures of proteins without clear templates. We present a broad number of applications that span from driving forward biochemical investigations that lack experimental structures to actually assisting experimental structure determination in X-ray diffraction, cryo-EM and other forms of integrative modeling. We also discuss issues that must be considered by users yet still require further developments, such as global and residue-wise model quality estimates and sources of residue coevolution other than monomeric tertiary structure.
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Affiliation(s)
- Luciano A Abriata
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Matteo Dal Peraro
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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Paquete CM, Rusconi G, Silva AV, Soares R, Louro RO. A brief survey of the "cytochromome". Adv Microb Physiol 2019; 75:69-135. [PMID: 31655743 DOI: 10.1016/bs.ampbs.2019.07.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Multihaem cytochromes c are widespread in nature where they perform numerous roles in diverse anaerobic metabolic pathways. This is achieved in two ways: multihaem cytochromes c display a remarkable diversity of ways to organize multiple hemes within the protein frame; and the hemes possess an intrinsic reactive versatility derived from diverse spin, redox and coordination states. Here we provide a brief survey of multihaem cytochromes c that have been characterized in the context of their metabolic role. The contribution of multihaem cytochromes c to dissimilatory pathways handling metallic minerals, nitrogen compounds, sulfur compounds, organic compounds and phototrophism are described. This aims to set the stage for the further exploration of the vast unknown "cytochromome" that can be anticipated from genomic databases.
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Significance of MccR, MccC, MccD, MccL and 8-methylmenaquinone in sulfite respiration of Wolinella succinogenes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:12-21. [DOI: 10.1016/j.bbabio.2018.10.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 09/26/2018] [Accepted: 10/13/2018] [Indexed: 11/17/2022]
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Abstract
The movement or trafficking of heme is critical for cellular functions (e.g., oxygen transport and energy production); however, intracellular heme is tightly regulated due to its inherent cytotoxicity. These factors, combined with the transient nature of transport, have resulted in a lack of direct knowledge on the mechanisms of heme binding and trafficking. Here, we used the cytochrome c biogenesis system II pathway as a model to study heme trafficking. System II is composed of two integral membrane proteins (CcsBA) which function to transport heme across the membrane and stereospecifically position it for covalent attachment to apocytochrome c. We mapped two heme binding domains in CcsBA and suggest a path for heme trafficking. These data, in combination with metagenomic coevolution data, are used to determine a structural model of CcsBA, leading to increased understanding of the mechanisms for heme transport and the cytochrome c synthetase function of CcsBA. Although intracellular heme trafficking must occur for heme protein assembly, only a few heme transporters have been unequivocally discovered and nothing is known about their structure or mechanisms. Cytochrome c biogenesis in prokaryotes requires the transport of heme from inside to outside for stereospecific attachment to cytochrome c via two thioether bonds (at CXXCH). The CcsBA integral membrane protein was shown to transport and attach heme (and thus is a cytochrome c synthetase), but the structure and mechanisms underlying these two activities are poorly understood. We employed a new cysteine/heme crosslinking tool that traps endogenous heme in heme binding sites. We combined these data with a comprehensive imidazole correction approach (for heme ligand interrogation) to map heme binding sites. Results illuminate the process of heme transfer through the membrane to an external binding site (called the WWD domain). Using meta-genomic data (GREMLIN) and Rosetta modeling programs, a structural model of the transmembrane (TM) regions in CcsBA were determined. The heme mapping data were then incorporated to model the TM heme binding site (with TM-His1 and TM-His2 as ligands) and the external heme binding WWD domain (with P-His1 and P-His2 as ligands). Other periplasmic structure/function studies facilitated modeling of the full CcsBA protein as a framework for understanding the mechanisms. Mechanisms are proposed for heme transport from TM-His to WWD/P-His and subsequent stereospecific attachment of heme. A ligand exchange of the P-His1 for histidine of CXXCH at the synthetase active site is suggested.
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Shevket SH, Gonzalez D, Cartwright JL, Kleanthous C, Ferguson SJ, Redfield C, Mavridou DAI. The CcmC-CcmE interaction during cytochrome c maturation by System I is driven by protein-protein and not protein-heme contacts. J Biol Chem 2018; 293:16778-16790. [PMID: 30206118 PMCID: PMC6204919 DOI: 10.1074/jbc.ra118.005024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 09/07/2018] [Indexed: 12/30/2022] Open
Abstract
Cytochromes c are ubiquitous proteins, essential for life in most organisms. Their distinctive characteristic is the covalent attachment of heme to their polypeptide chain. This post-translational modification is performed by a dedicated protein system, which in many Gram-negative bacteria and plant mitochondria is a nine-protein apparatus (CcmA-I) called System I. Despite decades of study, mechanistic understanding of the protein-protein interactions in this highly complex maturation machinery is still lacking. Here, we focused on the interaction of CcmC, the protein that sources the heme cofactor, with CcmE, the pivotal component of System I responsible for the transfer of the heme to the apocytochrome. Using in silico analyses, we identified a putative interaction site between these two proteins (residues Asp47, Gln50, and Arg55 on CcmC; Arg73, Asp101, and Glu105 on CcmE), and we validated our findings by in vivo experiments in Escherichia coli Moreover, employing NMR spectroscopy, we examined whether a heme-binding site on CcmE contributes to this interaction and found that CcmC and CcmE associate via protein-protein rather than protein-heme contacts. The combination of in vivo site-directed mutagenesis studies and high-resolution structural techniques enabled us to determine at the residue level the mechanism for the formation of one of the key protein complexes for cytochrome c maturation by System I.
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Affiliation(s)
- Shevket H Shevket
- the Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Diego Gonzalez
- the Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Quartier UNIL/Sorge, Lausanne, Switzerland
| | - Jared L Cartwright
- the Bioscience Technology Facility, Department of Biology, University of York, Wentworth Way, York YO10 5DD, United Kingdom
| | - Colin Kleanthous
- the Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Stuart J Ferguson
- the Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom,
| | - Christina Redfield
- the Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom,
| | - Despoina A I Mavridou
- From the MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, Kensington, London SW7 2DD, United Kingdom,
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