scholarly journals Structures of Rhodopseudomonas palustris RC-LH1 complexes with open or closed quinone channels

2021 ◽  
Vol 7 (3) ◽  
pp. eabe2631
Author(s):  
David J. K. Swainsbury ◽  
Pu Qian ◽  
Philip J. Jackson ◽  
Kaitlyn M. Faries ◽  
Dariusz M. Niedzwiedzki ◽  
...  
Keyword(s):  
Binding Sites ◽  
Rhodopseudomonas Palustris ◽  
Ring Closure ◽  
Light Harvesting Complex ◽  
The Core ◽  
Quinone Binding ◽  
Cryo Electron Microscopy ◽  
Unique Protein ◽  
Center Light ◽  
Resolution Structure

The reaction-center light-harvesting complex 1 (RC-LH1) is the core photosynthetic component in purple phototrophic bacteria. We present two cryo–electron microscopy structures of RC-LH1 complexes from Rhodopseudomonas palustris. A 2.65-Å resolution structure of the RC-LH114-W complex consists of an open 14-subunit LH1 ring surrounding the RC interrupted by protein-W, whereas the complex without protein-W at 2.80-Å resolution comprises an RC completely encircled by a closed, 16-subunit LH1 ring. Comparison of these structures provides insights into quinone dynamics within RC-LH1 complexes, including a previously unidentified conformational change upon quinone binding at the RC QB site, and the locations of accessory quinone binding sites that aid their delivery to the RC. The structurally unique protein-W prevents LH1 ring closure, creating a channel for accelerated quinone/quinol exchange.

scholarly journals The Structure of an Injectisome Export Gate Demonstrates Conservation of Architecture in the Core Export Gate between Flagellar and Virulence Type III Secretion Systems

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Steven Johnson ◽  
Lucas Kuhlen ◽  
Justin C. Deme ◽  
Patrizia Abrusci ◽  
Susan M. Lea
Keyword(s):  
Type Iii Secretion ◽  
Complex Analysis ◽  
Secretion Systems ◽  
Core Complex ◽  
Type Iii ◽  
The Core ◽  
Cryo Electron Microscopy ◽  
Type Iii Secretion Systems ◽  
Equivalent Complex ◽  
Resolution Structure

ABSTRACT Export of proteins through type III secretion systems (T3SS) is critical for motility and virulence of many major bacterial pathogens. Proteins are exported through a genetically defined export gate complex consisting of three proteins. We have recently shown at 4.2 Å that the flagellar complex of these three putative membrane proteins (FliPQR in flagellar systems, SctRST in virulence systems) assembles into an extramembrane helical assembly that likely seeds correct assembly of the rod. Here we present the structure of an equivalent complex from the Shigella virulence system at 3.5 Å by cryo-electron microscopy. This higher-resolution structure yields a more precise description of the structure and confirms the prediction of structural conservation in this core complex. Analysis of particle heterogeneity also suggests how the SctS/FliQ subunits sequentially assemble in the complex. IMPORTANCE Although predicted on the basis of sequence conservation, the work presented here formally demonstrates that all classes of type III secretion systems, flagellar or virulence, share the same architecture at the level of the core structures. This absolute conservation of the unusual extramembrane structure of the core export gate complex now allows work to move to focusing on both mechanistic studies of type III but also on fundamental studies of how such a complex is assembled.

scholarly journals The structure of an injectisome export gate demonstrates conservation of architecture in the core export gate between flagellar and virulence type three secretion systems

2019 ◽  
Author(s):  
Steven Johnson ◽  
Lucas Kuhlen ◽  
Justin C. Deme ◽  
Patrizia Abrusci ◽  
Susan M. Lea
Keyword(s):  
Electron Microscopy ◽  
Membrane Proteins ◽  
Complex Analysis ◽  
Secretion Systems ◽  
Core Complex ◽  
The Core ◽  
Cryo Electron Microscopy ◽  
Equivalent Complex ◽  
Type Three Secretion ◽  
Resolution Structure

AbstractExport of proteins through type three secretion systems (T3SS) is critical for motility and virulence of many major bacterial pathogens. Proteins are exported though a genetically defined export gate complex consisting of three proteins. We have recently shown at 4.2 Å that the flagellar complex of these three putative membrane proteins (FliPQR in flagellar systems, SctRST in virulence systems) assemble into an extra-membrane helical assembly that likely seeds correct assembly of the rod above. Here we present the structure of an equivalent complex from the more fragile Shigella virulence system at 3.5 Å by cryo-electron microscopy. This higher resolution structure reveals further detail and confirms the prediction of structural conservation in this core complex. Analysis of particle heterogeneity also reveals details of how the SctS/FliQ subunits sequentially assemble in the complex.

scholarly journals Flaviviruses have imperfect icosahedral symmetry

2018 ◽  
Vol 115 (45) ◽  
pp. 11608-11612 ◽  
Author(s):  
Matthew D. Therkelsen ◽  
Thomas Klose ◽  
Frank Vago ◽  
Wen Jiang ◽  
Michael G. Rossmann ◽  
...  
Keyword(s):  
Lipid Membrane ◽  
Viral Assembly ◽  
Icosahedral Symmetry ◽  
Proximal Pole ◽  
The Core ◽  
Cryo Electron Microscopy ◽  
Symmetry Constraints ◽  
Conformational Rearrangements ◽  
Mature Virus ◽  
Concentric Organization

Flaviviruses assemble initially in an immature, noninfectious state and undergo extensive conformational rearrangements to generate mature virus. Previous cryo-electron microscopy (cryo-EM) structural studies of flaviviruses assumed icosahedral symmetry and showed the concentric organization of the external glycoprotein shell, the lipid membrane, and the internal nucleocapsid core. We show here that when icosahedral symmetry constraints were excluded in calculating the cryo-EM reconstruction of an immature flavivirus, the nucleocapsid core was positioned asymmetrically with respect to the glycoprotein shell. The core was positioned closer to the lipid membrane at the proximal pole, and at the distal pole, the outer glycoprotein spikes and inner membrane leaflet were either perturbed or missing. In contrast, in the asymmetric reconstruction of a mature flavivirus, the core was positioned concentric with the glycoprotein shell. The deviations from icosahedral symmetry demonstrated that the core and glycoproteins have varied interactions, which likely promotes viral assembly and budding.

scholarly journals A resolution record for cryoEM

2021 ◽  
Vol 10 ◽  
Author(s):  
Jonathan Ashmore ◽  
Bridget Carragher ◽  
Peter B Rosenthal ◽  
William Weis
Keyword(s):  
Electron Microscopy ◽  
Image Analysis ◽  
Structure Determination ◽  
Test Specimen ◽  
Structural Information ◽  
Atomic Resolution ◽  
Fast Growing ◽  
Cryo Electron Microscopy ◽  
New Instrument ◽  
Resolution Structure

Cryo electron microscopy (cryoEM) is a fast-growing technique for structure determination. Two recent papers report the first atomic resolution structure of a protein obtained by averaging images of frozen-hydrated biomolecules. They both describe maps of symmetric apoferritin assemblies, a common test specimen, in unprecedented detail. New instrument improvements, different in the two studies, have contributed better images, and image analysis can extract structural information sufficient to resolve individual atomic positions. While true atomic resolution maps will not be routine for most proteins, the studies suggest structures determined by cryoEM will continue to improve, increasing their impact on biology and medicine.

scholarly journals Rapid high-resolution structure analysis of small, biotechnologically relevant enzymes by cryo-electron microscopy

2021 ◽  
Author(s):  
Nicole Dimos ◽  
Carl P.O. Helmer ◽  
Andrea M. Chanique ◽  
Markus C. Wahl ◽  
Robert Kourist ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Structural Biology ◽  
Structure Analysis ◽  
Cryo Electron Microscopy ◽  
High Resolution Structure ◽  
Fast Development ◽  
Pharmaceutical Industries ◽  
Exquisite Specificity ◽  
Resolution Structure

Enzyme catalysis has emerged as a key technology for developing efficient, sustainable processes in the chemical, biotechnological and pharmaceutical industries. Plants provide large and diverse pools of biosynthetic enzymes that facilitate complex reactions, such as the formation of intricate terpene carbon skeletons, with exquisite specificity. High-resolution structural analysis of these enzymes is crucial to understand their mechanisms and modulate their properties by targeted engineering. Although cryo-electron microscopy (cryo-EM) has revolutionized structural biology, its applicability to high-resolution structure analysis of comparatively small enzymes is so far largely unexplored. Here, we show that cryo-EM can reveal the structures of ~120 kDa plant borneol dehydrogenases at or below 2 Å resolution, paving the way for the fast development of new biocatalysts that provide access to bioactive terpenes and terpenoids.

scholarly journals Assisted assembly of bacteriophage T7 core components for genome translocation across the bacterial envelope

2021 ◽  
Vol 118 (34) ◽  
pp. e2026719118
Author(s):  
Mar Pérez-Ruiz ◽  
Mar Pulido-Cid ◽  
Juan Román Luque-Ortega ◽  
José María Valpuesta ◽  
Ana Cuervo ◽  
...  
Keyword(s):  
Bacteriophage T7 ◽  
Dna Translocation ◽  
Oligomeric State ◽  
Viral Dna ◽  
The Core ◽  
Cryo Electron Microscopy ◽  
Core Proteins ◽  
Core Components ◽  
Bacterial Cytoplasm ◽  
Bacterial Peptidoglycan

In most bacteriophages, genome transport across bacterial envelopes is carried out by the tail machinery. In viruses of the Podoviridae family, in which the tail is not long enough to traverse the bacterial wall, it has been postulated that viral core proteins assembled inside the viral head are translocated and reassembled into a tube within the periplasm that extends the tail channel. Bacteriophage T7 infects Escherichia coli, and despite extensive studies, the precise mechanism by which its genome is translocated remains unknown. Using cryo-electron microscopy, we have resolved the structure of two different assemblies of the T7 DNA translocation complex composed of the core proteins gp15 and gp16. Gp15 alone forms a partially folded hexamer, which is further assembled upon interaction with gp16 into a tubular structure, forming a channel that could allow DNA passage. The structure of the gp15–gp16 complex also shows the location within gp16 of a canonical transglycosylase motif involved in the degradation of the bacterial peptidoglycan layer. This complex docks well in the tail extension structure found in the periplasm of T7-infected bacteria and matches the sixfold symmetry of the phage tail. In such cases, gp15 and gp16 that are initially present in the T7 capsid eightfold-symmetric core would change their oligomeric state upon reassembly in the periplasm. Altogether, these results allow us to propose a model for the assembly of the core translocation complex in the periplasm, which furthers understanding of the molecular mechanism involved in the release of T7 viral DNA into the bacterial cytoplasm.

scholarly journals Myosin MyTH4-FERM structures highlight important principles of convergent evolution

2016 ◽  
Vol 113 (21) ◽  
pp. E2906-E2915 ◽  
Author(s):  
Vicente José Planelles-Herrero ◽  
Florian Blanc ◽  
Serena Sirigu ◽  
Helena Sirkia ◽  
Jeffrey Clause ◽  
...  
Keyword(s):  
Binding Sites ◽  
Convergent Evolution ◽  
Tail Domain ◽  
The Core ◽  
Binding Partners ◽  
The Social ◽  
Wide Range ◽  
Membrane Protrusions ◽  
Characteristic Features ◽  
Multifunctional Platform

Myosins containing MyTH4-FERM (myosin tail homology 4-band 4.1, ezrin, radixin, moesin, or MF) domains in their tails are found in a wide range of phylogenetically divergent organisms, such as humans and the social amoeba Dictyostelium (Dd). Interestingly, evolutionarily distant MF myosins have similar roles in the extension of actin-filled membrane protrusions such as filopodia and bind to microtubules (MT), suggesting that the core functions of these MF myosins have been highly conserved over evolution. The structures of two DdMyo7 signature MF domains have been determined and comparison with mammalian MF structures reveals that characteristic features of MF domains are conserved. However, across millions of years of evolution conserved class-specific insertions are seen to alter the surfaces and the orientation of subdomains with respect to each other, likely resulting in new sites for binding partners. The MyTH4 domains of Myo10 and DdMyo7 bind to MT with micromolar affinity but, surprisingly, their MT binding sites are on opposite surfaces of the MyTH4 domain. The structural analysis in combination with comparison of diverse MF myosin sequences provides evidence that myosin tail domain features can be maintained without strict conservation of motifs. The results illustrate how tuning of existing features can give rise to new structures while preserving the general properties necessary for myosin tails. Thus, tinkering with the MF domain enables it to serve as a multifunctional platform for cooperative recruitment of various partners, allowing common properties such as autoinhibition of the motor and microtubule binding to arise through convergent evolution.

Structure of the maize photosystem I supercomplex with light-harvesting complexes I and II

Science ◽  
2018 ◽  
Vol 360 (6393) ◽  
pp. 1109-1113 ◽  
Author(s):  
Xiaowei Pan ◽  
Jun Ma ◽  
Xiaodong Su ◽  
Peng Cao ◽  
Wenrui Chang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Energy Transfer ◽  
Complex I ◽  
Light Harvesting ◽  
Light Conditions ◽  
Light Harvesting Complexes ◽  
Light Harvesting Complex ◽  
Cryo Electron Microscopy ◽  
Photosystems I And Ii ◽  
Light Harvesting Complex Ii

Plants regulate photosynthetic light harvesting to maintain balanced energy flux into photosystems I and II (PSI and PSII). Under light conditions favoring PSII excitation, the PSII antenna, light-harvesting complex II (LHCII), is phosphorylated and forms a supercomplex with PSI core and the PSI antenna, light-harvesting complex I (LHCI). Both LHCI and LHCII then transfer excitation energy to the PSI core. We report the structure of maize PSI-LHCI-LHCII solved by cryo–electron microscopy, revealing the recognition site between LHCII and PSI. The PSI subunits PsaN and PsaO are observed at the PSI-LHCI interface and the PSI-LHCII interface, respectively. Each subunit relays excitation to PSI core through a pair of chlorophyll molecules, thus revealing previously unseen paths for energy transfer between the antennas and the PSI core.

Plant and Algal PSII–LHCII Supercomplexes: Structure, Evolution and Energy Transfer

2021 ◽  
Author(s):  
Xin Sheng ◽  
Zhenfeng Liu ◽  
Eunchul Kim ◽  
Jun Minagawa
Keyword(s):  
Energy Transfer ◽  
Light Harvesting ◽  
Chemical Form ◽  
Structure Evolution ◽  
Light Harvesting Complex ◽  
Green Algal ◽  
Cryo Electron Microscopy ◽  
Light Harvesting Complex Ii ◽  
Overall Efficiency ◽  
Psii Subunits

Abstract Photosynthesis is the process conducted by plants and algae to capture photons and store their energy into a chemical form. The light-harvesting, excitation transfer, charge separation, and electron transfer in photosystem II (PSII) are the critical initial reactions of photosynthesis and thereby largely determine its overall efficiency. In this review, we outline the rapidly accumulating knowledges about the architectures and assemblies of plant and green algal PSII–light harvesting complex II (LHCII) supercomplexes with a particular focus on new insights provided by the recent high-resolution cryo-electron microscopy (cryo-EM) map of the supercomplexes from a green alga Chlamydomonas reinhardtii. We make pair-wise comparative analyses between the supercomplexes from plants and green algae to gain insights about the evolution of the PSII–LHCII supercomplexes involving the peripheral small PSII subunits that might have been acquired during the evolution, and about the energy transfer pathways that define their light-harvesting and photoprotective properties.

Sign in / Sign up

Export Citation Format

Share Document