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1.
Nat Commun ; 13(1): 1278, 2022 03 11.
Artigo em Inglês | MEDLINE | ID: mdl-35277487

RESUMO

Yeast Cadmium Factor 1 (Ycf1) sequesters heavy metals and glutathione into the vacuole to counter cell stress. Ycf1 belongs to the ATP binding cassette C-subfamily (ABCC) of transporters, many of which are regulated by phosphorylation on intrinsically-disordered domains. The regulatory mechanism of phosphorylation is still poorly understood. Here, we report two cryo-EM structures of Ycf1 at 3.4 Å and 4.0 Å resolution in inward-facing open conformations that capture previously unobserved ordered states of the intrinsically disordered regulatory domain (R-domain). R-domain phosphorylation is clearly evident and induces a topology promoting electrostatic and hydrophobic interactions with Nucleotide Binding Domain 1 (NBD1) and the Lasso motif. These interactions stay constant between the structures and are related by rigid body movements of the NBD1/R-domain complex. Biochemical data further show R-domain phosphorylation reorganizes the Ycf1 architecture and is required for maximal ATPase activity. Together, we provide insights into how R-domains control ABCC transporter activity.


Assuntos
Transportadores de Cassetes de Ligação de ATP , Proteínas de Saccharomyces cerevisiae , Transportadores de Cassetes de Ligação de ATP/metabolismo , Cádmio/metabolismo , Proteínas de Membrana Transportadoras , Fosforilação , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo
2.
J Vis Exp ; (177)2021 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-34866621

RESUMO

Electron crystallography is a powerful tool for high-resolution structure determination. Macromolecules such as soluble or membrane proteins can be grown into highly ordered two-dimensional (2D) crystals under favorable conditions. The quality of the grown 2D crystals is crucial to the resolution of the final reconstruction via 2D image processing. Over the years, lipid monolayers have been used as a supporting layer to foster the 2D crystallization of peripheral membrane proteins as well as soluble proteins. This method can also be applied to 2D crystallization of integral membrane proteins but requires more extensive empirical investigation to determine detergent and dialysis conditions to promote partitioning to the monolayer. A lipid monolayer forms at the air-water interface such that the polar lipid head groups remain hydrated in the aqueous phase and the non-polar, acyl chains, tails partition into the air, breaking the surface tension and flattening the water surface. The charged nature or distinctive chemical moieties of the head groups provide affinity for proteins in solution, promoting binding for 2D array formation. A newly formed monolayer with the 2D array can be readily transfer into an electron microscope (EM) on a carbon-coated copper grid used to lift and support the crystalline array. In this work, we describe a lipid monolayer methodology for cryogenic electron microscopic (cryo-EM) imaging.


Assuntos
Elétrons , Diálise Renal , Microscopia Crioeletrônica/métodos , Cristalografia por Raios X , Lipídeos/química , Proteínas de Membrana/química
4.
Sci Adv ; 7(49): eabl8213, 2021 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-34851659

RESUMO

Vaccines derived from chimpanzee adenovirus Y25 (ChAdOx1), human adenovirus type 26 (HAdV-D26), and human adenovirus type 5 (HAdV-C5) are critical in combatting the severe acute respiratory coronavirus 2 (SARS-CoV-2) pandemic. As part of the largest vaccination campaign in history, ultrarare side effects not seen in phase 3 trials, including thrombosis with thrombocytopenia syndrome (TTS), a rare condition resembling heparin-induced thrombocytopenia (HIT), have been observed. This study demonstrates that all three adenoviruses deployed as vaccination vectors versus SARS-CoV-2 bind to platelet factor 4 (PF4), a protein implicated in the pathogenesis of HIT. We have determined the structure of the ChAdOx1 viral vector and used it in state-of-the-art computational simulations to demonstrate an electrostatic interaction mechanism with PF4, which was confirmed experimentally by surface plasmon resonance. These data confirm that PF4 is capable of forming stable complexes with clinically relevant adenoviruses, an important step in unraveling the mechanisms underlying TTS.

5.
Elife ; 102021 08 26.
Artigo em Inglês | MEDLINE | ID: mdl-34435952

RESUMO

Photosynthetic organisms have adapted to survive a myriad of extreme environments from the earth's deserts to its poles, yet the proteins that carry out the light reactions of photosynthesis are highly conserved from the cyanobacteria to modern day crops. To investigate adaptations of the photosynthetic machinery in cyanobacteria to excessive light stress, we isolated a new strain of cyanobacteria, Cyanobacterium aponinum 0216, from the extreme light environment of the Sonoran Desert. Here we report the biochemical characterization and the 2.7 Å resolution structure of trimeric photosystem I from this high-light-tolerant cyanobacterium. The structure shows a new conformation of the PsaL C-terminus that supports trimer formation of cyanobacterial photosystem I. The spectroscopic analysis of this photosystem I revealed a decrease in far-red absorption, which is attributed to a decrease in the number of long- wavelength chlorophylls. Using these findings, we constructed two chimeric PSIs in Synechocystis sp. PCC 6803 demonstrating how unique structural features in photosynthetic complexes can change spectroscopic properties, allowing organisms to thrive under different environmental stresses.


Assuntos
Cianobactérias/genética , Cianobactérias/fisiologia , Complexo de Proteína do Fotossistema I/química , Complexo de Proteína do Fotossistema I/genética , Aclimatação , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Clorofila , Microscopia Crioeletrônica , Luz , Modelos Moleculares , Fotossíntese , Complexo de Proteína do Fotossistema I/metabolismo , Conformação Proteica , Synechocystis/metabolismo
6.
Int J Mol Sci ; 22(15)2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34360842

RESUMO

IBMPFD/ALS is a genetic disorder caused by a single amino acid mutation on the p97 ATPase, promoting ATPase activity and cofactor dysregulation. The disease mechanism underlying p97 ATPase malfunction remains unclear. To understand how the mutation alters the ATPase regulation, we assembled a full-length p97R155H with its p47 cofactor and first visualized their structures using single-particle cryo-EM. More than one-third of the population was the dodecameric form. Nucleotide presence dissociates the dodecamer into two hexamers for its highly elevated function. The N-domains of the p97R155H mutant all show up configurations in ADP- or ATPγS-bound states. Our functional and structural analyses showed that the p47 binding is likely to impact the p97R155H ATPase activities via changing the conformations of arginine fingers. These functional and structural analyses underline the ATPase dysregulation with the miscommunication between the functional modules of the p97R155H.


Assuntos
Demência Frontotemporal/metabolismo , Modelos Moleculares , Distrofia Muscular do Cíngulo dos Membros/metabolismo , Mutação , Miosite de Corpos de Inclusão/metabolismo , Osteíte Deformante/metabolismo , Proteínas de Ligação a Fator Solúvel Sensível a N-Etilmaleimida/metabolismo , Proteína com Valosina/genética , Demência Frontotemporal/genética , Humanos , Microscopia Eletrônica de Transmissão , Distrofia Muscular do Cíngulo dos Membros/genética , Miosite de Corpos de Inclusão/genética , Osteíte Deformante/genética , Conformação Proteica , Proteína com Valosina/metabolismo
7.
J Am Chem Soc ; 143(23): 8639-8646, 2021 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-34078072

RESUMO

Metal nanostructures of chiral geometry interacting with light via surface plasmon resonances can produce tailorable optical activity with their structural alterations. However, bottom-up fabrication of arbitrary chiral metal nanostructures with precise size and morphology remains a synthetic challenge. Here we develop a DNA origami-enabled aqueous solution metallization strategy to prescribe the chirality of silver nanostructures in three dimensions. We find that diamine silver(I) complexes coordinate with the bases of prescribed single-stranded protruding clustered DNA (pcDNA) on DNA origami via synergetic interactions including coordination, hydrogen bonds, and ion-π interaction, which induce site-specific pcDNA condensation and local enrichment of silver precursors that lowers the activation energy for nucleation. Using tubular DNA origami-based metallization, we obtain helical silver patterns up to a micrometer in length with well-defined chirality and pitches. We further demonstrate tailorable plasmonic optical activity of metallized chiral silver nanostructures. This method opens new pathways to synthesize programmable inorganic materials with arbitrary morphology and chirality.


Assuntos
DNA/química , Nanopartículas Metálicas/química , Prata/química , Ligação de Hidrogênio , Tamanho da Partícula
8.
Structure ; 29(8): 873-885.e5, 2021 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-33784495

RESUMO

Taspase1 is an Ntn-hydrolase overexpressed in primary human cancers, coordinating cancer cell proliferation, invasion, and metastasis. Loss of Taspase1 activity disrupts proliferation of human cancer cells in vitro and in mouse models of glioblastoma. Taspase1 is synthesized as an inactive proenzyme, becoming active upon intramolecular cleavage. The activation process changes the conformation of a long fragment at the C-terminus of the α subunit, for which no full-length structural information exists and whose function is poorly understood. We present a cloning strategy to generate a circularly permuted form of Taspase1 to determine the crystallographic structure of active Taspase1. We discovered that this region forms a long helix and is indispensable for the catalytic activity of Taspase1. Our study highlights the importance of this element for the enzymatic activity of Ntn-hydrolases, suggesting that it could be a potential target for the design of inhibitors with potential to be developed into anticancer therapeutics.


Assuntos
Endopeptidases/química , Endopeptidases/metabolismo , Clonagem Molecular , Cristalografia por Raios X , Difusão Dinâmica da Luz , Endopeptidases/genética , Ativação Enzimática , Humanos , Modelos Moleculares , Domínios Proteicos , Estrutura Secundária de Proteína
9.
J Microsc ; 282(3): 215-223, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33305823

RESUMO

Infrared spectroscopy is a powerful technique for characterising protein structure. It is now possible to record energy losses corresponding to the infrared region in the electron microscope and to avoid damage by positioning the probe in the region adjacent to the structure being studied. Spectra from bacteriorhodopsin, a protein that is predominately a α helix, and OmpF porin, a protein that is mainly ß sheet show significant differences over a spectral range from ∼0.1 to 0.25 eV (∼1000 to 1800 cm-1 ). Although the energy resolution equivalent to 60 cm-1 is inferior to Fourier Transform InfraRed Spectroscopy (FTIR) the spectra are very sensitive to molecular orientation. Polar bonds aligned parallel to the specimen grid make particularly strong contributions to the energy loss spectra. Ultra-high-resolution energy loss spectroscopy in the electron microscope can potentially add useful information to imaging and diffraction for determining the secondary structure misfolding believed to be responsible for dementia diseases such as Alzheimer's.


Proteins are long linear molecular chains that when folded into complex three-dimensional shapes enable them to perform their biological functions. Infrared spectroscopy is a powerful technique for characterising protein folds, especially the proportions of helices and sheets that are significant building blocks in the overall structure. Traditionally, it was only possible to record infrared spectra from large amounts of material. In this paper, we show that it is possible to record the equivalent of the infrared spectrum from regions much smaller than a cell using a high-performance spectrometer coupled to electron microscopy. One great advantage is that the spectroscopic measurements can be combined with the standard high-resolution imaging and other characterisation techniques available in the electron microscope. We believe expansion of this method will impact diseases such as Alzheimer's, which are believed to be the results of an incorrect folding process. Our technique, where we combine infrared spectroscopic measurements with electron microscopy, could be invaluable in characterising the critical early stages of protein misfolding and/or assembly. This information will be invaluable in disease prognosis and the search for potential therapies.


Assuntos
Elétrons , Proteínas , Estrutura Secundária de Proteína , Espectroscopia de Infravermelho com Transformada de Fourier
10.
Nat Commun ; 11(1): 6015, 2020 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-33219216

RESUMO

A Correction to this paper has been published: https://doi.org/10.1038/s41467-020-19953-w.

11.
Nat Commun ; 11(1): 5279, 2020 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-33077842

RESUMO

Photosystem I coordinates more than 90 chlorophylls in its core antenna while achieving near perfect quantum efficiency. Low energy chlorophylls (also known as red chlorophylls) residing in the antenna are important for energy transfer dynamics and yield, however, their precise location remained elusive. Here, we construct a chimeric Photosystem I complex in Synechocystis PCC 6803 that shows enhanced absorption in the red spectral region. We combine Cryo-EM and spectroscopy to determine the structure-function relationship in this red-shifted Photosystem I complex. Determining the structure of this complex reveals the precise architecture of the low energy site as well as large scale structural heterogeneity which is probably universal to all trimeric Photosystem I complexes. Identifying the structural elements that constitute red sites can expand the absorption spectrum of oxygenic photosynthetic and potentially modulate light harvesting efficiency.

12.
Commun Biol ; 3(1): 482, 2020 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-32879423

RESUMO

In higher plants, chloroplast ATP synthase has a unique redox switch on its γ subunit that modulates enzyme activity to limit ATP hydrolysis at night. To understand the molecular details of the redox modulation, we used single-particle cryo-EM to determine the structures of spinach chloroplast ATP synthase in both reduced and oxidized states. The disulfide linkage of the oxidized γ subunit introduces a torsional constraint to stabilize the two ß hairpin structures. Once reduced, free cysteines alleviate this constraint, resulting in a concerted motion of the enzyme complex and a smooth transition between rotary states to facilitate the ATP synthesis. We added an uncompetitive inhibitor, tentoxin, in the reduced sample to limit the flexibility of the enzyme and obtained high-resolution details. Our cryo-EM structures provide mechanistic insight into the redox modulation of the energy regulation activity of chloroplast ATP synthase.


Assuntos
ATPases de Cloroplastos Translocadoras de Prótons/química , ATPases de Cloroplastos Translocadoras de Prótons/metabolismo , Spinacia oleracea/enzimologia , Biocatálise , ATPases de Cloroplastos Translocadoras de Prótons/ultraestrutura , Microscopia Crioeletrônica , Luz , Modelos Biológicos , Modelos Moleculares , Nucleotídeos/metabolismo , Oxirredução , Domínios Proteicos , Subunidades Proteicas/química , Estatística como Assunto , Relação Estrutura-Atividade
13.
Mol Cell ; 80(1): 59-71.e4, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-32818430

RESUMO

Cardiac disease remains the leading cause of morbidity and mortality worldwide. The ß1-adrenergic receptor (ß1-AR) is a major regulator of cardiac functions and is downregulated in the majority of heart failure cases. A key physiological process is the activation of heterotrimeric G-protein Gs by ß1-ARs, leading to increased heart rate and contractility. Here, we use cryo-electron microscopy and functional studies to investigate the molecular mechanism by which ß1-AR activates Gs. We find that the tilting of α5-helix breaks a hydrogen bond between the sidechain of His373 in the C-terminal α5-helix and the backbone carbonyl of Arg38 in the N-terminal αN-helix of Gαs. Together with the disruption of another interacting network involving Gln59 in the α1-helix, Ala352 in the ß6-α5 loop, and Thr355 in the α5-helix, these conformational changes might lead to the deformation of the GDP-binding pocket. Our data provide molecular insights into the activation of G-proteins by G-protein-coupled receptors.


Assuntos
Subunidades alfa Gs de Proteínas de Ligação ao GTP/química , Subunidades alfa Gs de Proteínas de Ligação ao GTP/metabolismo , Isoproterenol/metabolismo , Receptores Adrenérgicos beta 1/química , Receptores Adrenérgicos beta 1/metabolismo , Animais , Sítios de Ligação , Bovinos , Linhagem Celular , Guanosina Difosfato/metabolismo , Guanosina Trifosfato/metabolismo , Modelos Moleculares , Ligação Proteica , Domínios Proteicos , Estrutura Secundária de Proteína
14.
Structure ; 28(11): 1206-1217.e4, 2020 11 03.
Artigo em Inglês | MEDLINE | ID: mdl-32783951

RESUMO

The 26S proteasome is specialized for regulated protein degradation and formed by a dynamic regulatory particle (RP) that caps a hollow cylindrical core particle (CP) where substrates are proteolyzed. Its diverse substrates unify as proteasome targets by ubiquitination. We used cryogenic electron microscopy (cryo-EM) to study how human 26S proteasome interacts with M1-linked hexaubiquitin (M1-Ub6) unanchored to a substrate and E3 ubiquitin ligase E6AP/UBE3A. Proteasome structures are available with model substrates extending through the RP ATPase ring and substrate-conjugated K63-linked ubiquitin chains present at inhibited deubiquitinating enzyme hRpn11 and the nearby ATPase hRpt4/hRpt5 coiled coil. In this study, we find M1-Ub6 at the hRpn11 site despite the absence of conjugated substrate, indicating that ubiquitin binding at this location does not require substrate interaction with the RP. Moreover, unanchored M1-Ub6 binds to this hRpn11 site of the proteasome with the CP gating residues in both the closed and opened conformational states.


Assuntos
Adenosina Trifosfatases/química , Poliubiquitina/química , Complexo de Endopeptidases do Proteassoma/química , Transativadores/química , Ubiquitina-Proteína Ligases/química , Ubiquitina/química , Adenosina Trifosfatases/genética , Adenosina Trifosfatases/metabolismo , Sítios de Ligação , Microscopia Crioeletrônica , Expressão Gênica , Humanos , Simulação de Acoplamento Molecular , Poliubiquitina/genética , Poliubiquitina/metabolismo , Complexo de Endopeptidases do Proteassoma/genética , Complexo de Endopeptidases do Proteassoma/metabolismo , Ligação Proteica , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , Proteólise , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Especificidade por Substrato , Transativadores/genética , Transativadores/metabolismo , Ubiquitina/genética , Ubiquitina/metabolismo , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitinação
15.
Ultramicroscopy ; 216: 113048, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32570132

RESUMO

Analysis of metal-organic framework (MOF) structure by electron microscopy and electron diffraction offers an alternative to growing large single crystals for high-resolution X-ray diffraction. However, many MOFs are electron beam-sensitive, which can make structural analysis using high-resolution electron microscopy difficult. In this work we use the microcrystal electron diffraction (MicroED) method to collect high-resolution electron diffraction data from a model beam-sensitive MOF, ZIF-8. The diffraction data could be used to determine the structure of ZIF-8 to 0.87 Å from a single ZIF-8 nanocrystal, and this refined structure compares well with previously published structures of ZIF-8 determined by X-ray crystallography. This demonstrates that MicroED can be a valuable tool for the analysis of beam-sensitive MOF structures directly from nano and microcrystalline material.

16.
Nanoscale ; 12(9): 5363-5367, 2020 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-32100774

RESUMO

Nanodiamonds are increasingly used in many areas of science and technology, yet, their colloidal properties remain poorly understood. Here we use direct imaging as well as light and X-ray scattering reveal that purified detonation nanodiamond (DND) particles in an aqueous environment exhibit a self-assembled lace-like network, even without additional surface modification. Such behaviour is previously unknown and contradicts the current consensus that DND exists as mono-dispersed single particles. With the aid of mesoscale simulations, we show that the lace network is likely the result of competition between a short-ranged electrostatic attraction between faceted particles and a longer-ranged repulsion arising from the interaction between the surface functional groups and the surrounding water molecules which prevents complete flocculation. Our findings have significant implications for applications of DND where control of the aggregation behaviour is critical to performance.

17.
Sci Adv ; 6(6): eaay6415, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32076649

RESUMO

Phototrophic organisms are superbly adapted to different light environments but often must acclimate to challenging competition for visible light wavelengths in their niches. Some cyanobacteria overcome this challenge by expressing paralogous photosynthetic proteins and by synthesizing and incorporating ~8% chlorophyll f into their Photosystem I (PSI) complexes, enabling them to grow under far-red light (FRL). We solved the structure of FRL-acclimated PSI from the cyanobacterium Fischerella thermalis PCC 7521 by single-particle, cryo-electron microscopy to understand its structural and functional differences. Four binding sites occupied by chlorophyll f are proposed. Subtle structural changes enable FRL-adapted PSI to extend light utilization for oxygenic photosynthesis to nearly 800 nm. This structure provides a platform for understanding FRL-driven photosynthesis and illustrates the robustness of adaptive and acclimation mechanisms in nature.


Assuntos
Luz , Modelos Moleculares , Fotossíntese , Complexo de Proteína do Fotossistema I/química , Complexo de Proteína do Fotossistema I/metabolismo , Sequência de Aminoácidos , Sítios de Ligação , Microscopia Crioeletrônica , Pigmentos Biológicos/química , Ligação Proteica , Conformação Proteica , Relação Estrutura-Atividade
18.
Cell ; 180(4): 633-644.e12, 2020 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-32032505

RESUMO

Tau aggregation into insoluble filaments is the defining pathological hallmark of tauopathies. However, it is not known what controls the formation and templated seeding of strain-specific structures associated with individual tauopathies. Here, we use cryo-electron microscopy (cryo-EM) to determine the structures of tau filaments from corticobasal degeneration (CBD) human brain tissue. Cryo-EM and mass spectrometry of tau filaments from CBD reveal that this conformer is heavily decorated with posttranslational modifications (PTMs), enabling us to map PTMs directly onto the structures. By comparing the structures and PTMs of tau filaments from CBD and Alzheimer's disease, it is found that ubiquitination of tau can mediate inter-protofilament interfaces. We propose a structure-based model in which cross-talk between PTMs influences tau filament structure, contributing to the structural diversity of tauopathy strains. Our approach establishes a framework for further elucidating the relationship between the structures of polymorphic fibrils, including their PTMs, and neurodegenerative disease.


Assuntos
Processamento de Proteína Pós-Traducional , Tauopatias/metabolismo , Proteínas tau/química , Idoso , Microscopia Crioeletrônica , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Agregação Patológica de Proteínas/metabolismo , Agregação Patológica de Proteínas/patologia , Tauopatias/patologia , Proteínas tau/metabolismo
19.
Nat Mater ; 19(7): 781-788, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-31873228

RESUMO

Nature has evolved strategies to encode information within a single biopolymer to program biomolecular interactions with characteristic stoichiometry, orthogonality and reconfigurability. Nevertheless, synthetic approaches for programming molecular reactions or assembly generally rely on the use of multiple polymer chains (for example, patchy particles). Here we demonstrate a method for patterning colloidal gold nanoparticles with valence bond analogues using single-stranded DNA encoders containing polyadenine (polyA). By programming the order, length and sequence of each encoder with alternating polyA/non-polyA domains, we synthesize programmable atom-like nanoparticles (PANs) with n-valence that can be used to assemble a spectrum of low-coordination colloidal molecules with different composition, size, chirality and linearity. Moreover, by exploiting the reconfigurability of PANs, we demonstrate dynamic colloidal bond-breaking and bond-formation reactions, structural rearrangement and even the implementation of Boolean logic operations. This approach may be useful for generating responsive functional materials for distinct technological applications.


Assuntos
Engenharia Química , DNA de Cadeia Simples/química , Nanopartículas Metálicas/química , Coloides/química , Ouro/química
20.
Nat Struct Mol Biol ; 26(6): 443-449, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31133699

RESUMO

Photochemical conversion in oxygenic photosynthesis takes place in two large protein-pigment complexes named photosystem II and photosystem I (PSII and PSI, respectively). Photosystems associate with antennae in vivo to increase the size of photosynthetic units to hundreds or thousands of pigments. Regulation of the interactions between antennae and photosystems allows photosynthetic organisms to adapt to their environment. In low-iron environments, cyanobacteria express IsiA, a PSI antenna, critical to their survival. Here we describe the structure of the PSI-IsiA complex isolated from the mesophilic cyanobacterium Synechocystis sp. PCC 6803. This 2-MDa photosystem-antenna supercomplex structure reveals more than 700 pigments coordinated by 51 subunits, as well as the mechanisms facilitating the self-assembly and association of IsiA with multiple PSI assemblies.


Assuntos
Proteínas de Bactérias/química , Complexos de Proteínas Captadores de Luz/química , Complexo de Proteína do Fotossistema I/química , Synechocystis/química , Proteínas de Bactérias/ultraestrutura , Microscopia Crioeletrônica , Complexos de Proteínas Captadores de Luz/ultraestrutura , Modelos Moleculares , Complexo de Proteína do Fotossistema I/ultraestrutura , Conformação Proteica , Multimerização Proteica , Subunidades Proteicas/química
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