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Beta barrell membrane protein

Kornelius Zeth, Ulrich Zachariae
Mitochondria are evolutionarily related to Gram-negative bacteria and both comprise two membrane systems with strongly differing protein composition. The major protein in the outer membrane of mitochondria is the voltage-dependent anion channel (VDAC), which mediates signal transmission across the outer membrane but also the exchange of metabolites, most importantly ADP and ATP. More than 30 years after its discovery three identical high-resolution structures were determined in 2008. These structures show a 19-stranded anti-parallel beta-barrel with an N-terminal helix located inside...
2018: Frontiers in Physiology
Jonathan Shearer, Syma Khalid
We use coarse-grain molecular simulations to investigate the structural and dynamics differences between an asymmetric and a symmetrical membrane, both containing beta barrel transmembrane proteins. We find in where the dynamics of the two leaflets differ greatly, the slowest leaflet dominates the structural effects and importance of protein-lipid interactions.
January 29, 2018: Scientific Reports
Konstantinos D Tsirigos, Sudha Govindarajan, Claudio Bassot, Åke Västermark, John Lamb, Nanjiang Shu, Arne Elofsson
Transmembrane proteins perform a variety of important biological functions necessary for the survival and growth of the cells. Membrane proteins are built up by transmembrane segments that span the lipid bilayer. The segments can either be in the form of hydrophobic alpha-helices or beta-sheets which create a barrel. A fundamental aspect of the structure of transmembrane proteins is the membrane topology, that is, the number of transmembrane segments, their position in the protein sequence and their orientation in the membrane...
October 26, 2017: Current Opinion in Structural Biology
Albert Ng, Dong Si
Cryo-electron microscopy (cryo-EM) is a technique that produces three-dimensional density maps of large protein complexes. This allows for the study of the structure of these proteins. Identifying the secondary structures within proteins is vital to understanding the overall structure and function of the protein. The [Formula: see text]-barrel is one such secondary structure, commonly found in lipocalins and membrane proteins. In this article, we present a novel approach that utilizes genetic algorithms, kd-trees, and ray tracing to automatically detect and extract [Formula: see text]-barrels from cryo-EM density maps...
October 16, 2017: Journal of Computational Biology: a Journal of Computational Molecular Cell Biology
Avinash Kumar Thakur, Motahareh Ghahari Larimi, Kristin Gooden, Liviu Movileanu
There have been only a few studies reporting on the impact of polyhistidine affinity tags on the structure, function, and dynamics of proteins. Because of the relatively short size of the tags, they are often thought to have little or no effect on the conformation or activity of a protein. Here, using membrane protein design and single-molecule electrophysiology, we determined that the presence of a hexahistidine arm at the N-terminus of a truncated FhuA-based protein nanopore, leaving the C-terminus untagged, produces an unusual increase in the unitary conductance to ∼8 nS in 1 M KCl...
September 12, 2017: Biochemistry
Zhen Zhang, Rongxing Tang, Dewu Zhu, Wenfeng Wang, Li Yi, Lixin Ma
Protein secretion in Escherichia coli is usually led by a signal peptide that targets the protein to specific secretory pathways. In this study, we demonstrated that the superfolder green fluorescent protein (sfGFP) could be served as a non-signal peptide to guide protein auto-secretion in E. coli. This auto-secretion was characterized as a three-step process through the sub-cellular localization analysis: inner membrane trans-location followed by anchoring at outer membrane, and then being released into culture media...
August 1, 2017: Scientific Reports
Rebecca S Bamert, Karl Lundquist, Hyea Hwang, Chaille T Webb, Takoya Shiota, Christopher J Stubenrauch, Mathew J Belousoff, Robert J A Goode, Ralf B Schittenhelm, Richard Zimmerman, Martin Jung, James C Gumbart, Trevor Lithgow
The assembly of proteins into bacterial outer membranes is a key cellular process that we are only beginning to understand, mediated by the β-barrel assembly machinery (BAM). Two crucial elements of that machinery are the core BAM complex and the translocation and assembly module (TAM), with each containing a member of the Omp85 superfamily of proteins: BamA in the BAM complex, TamA in the TAM. Here, we used the substrate protein FimD as a model to assess the selectivity of substrate interactions for the TAM relative to those of the BAM complex...
October 2017: Molecular Microbiology
Anna Konovalova
Surface-exposed proteins of Gram-negative bacteria are represented by integral outer membrane beta-barrel proteins and lipoproteins. No computational methods exist for predicting surface-exposed lipoproteins, and therefore lipoprotein topology must be experimentally tested. This chapter describes three distinct but complementary methods for the detection of surface-exposed proteins: cell surface protein labeling, accessibility to extracellular protease and antibodies.
2017: Methods in Molecular Biology
Yogesh Hooda, Christine C L Lai, Trevor F Moraes
The surfaces of many Gram-negative bacteria are decorated with soluble proteins anchored to the outer membrane via an acylated N-terminus; these proteins are referred to as surface lipoproteins or SLPs. In Neisseria meningitidis , SLPs such as transferrin-binding protein B (TbpB) and factor-H binding protein (fHbp) are essential for host colonization and infection because of their essential roles in iron acquisition and immune evasion, respectively. Recently, we identified a family of outer membrane proteins called Slam (Surface lipoprotein assembly modulator) that are essential for surface display of neisserial SLPs...
2017: Frontiers in Cellular and Infection Microbiology
Simona Reina, Vito De Pinto
BACKGROUND: VDAC (Voltage-Dependent Anion selective Channel) is a small family of abundant pore-forming proteins located in the outer mitochondrial membrane. Their role range from the most intuitive, the formation of a hydrophilic conduit through the membrane thanks to its beta-barrel structure, to less understood functions that make them essential actors in the cross-talk between the bioenergetics metabolism and the cytosol components. Due to this localization, VDAC1, in particular, has been reported to be involved in apoptosis, Hexokinase and tubulin binding, and in the Warburg effect...
2017: Current Medicinal Chemistry
Max J Temple, Fiona Cuskin, Arnaud Baslé, Niall Hickey, Gaetano Speciale, Spencer J Williams, Harry J Gilbert, Elisabeth C Lowe
Glycans are major nutrients available to the human gut microbiota. The Bacteroides are generalist glycan degraders, and this function is mediated largely by polysaccharide utilization loci (PULs). The genomes of several Bacteroides species contain a PUL, PUL1,6-β-glucan , that was predicted to target mixed linked plant 1,3;1,4-β-glucans. To test this hypothesis we characterized the proteins encoded by this locus in Bacteroides thetaiotaomicron , a member of the human gut microbiota. We show here that PUL1,6-β-glucan does not orchestrate the degradation of a plant polysaccharide but targets a fungal cell wall glycan, 1,6-β-glucan, which is a growth substrate for the bacterium...
June 23, 2017: Journal of Biological Chemistry
Mahnoush Babaei, Isaac C Jones, Kaushik Dayal, Meagan S Mauter
The behavior of large, complex molecules in the presence of magnetic fields is experimentally challenging to measure and computationally intensive to predict. This work proposes a novel, mixed-methods approach for efficiently computing the principal magnetic susceptibilities and diamagnetic anisotropy of membrane proteins. The hierarchical primary (amino acid), secondary (α helical and β sheet), and tertiary (α helix and β barrel) structure of transmembrane proteins enables analysis of a complex molecule using discrete subunits of varying size and resolution...
June 13, 2017: Journal of Chemical Theory and Computation
Abigail I Fish, Sean P Riley, Birendra Singh, Kristian Riesbeck, Juan J Martinez
Spotted fever group (SFG) Rickettsia species are inoculated into the mammalian bloodstream by hematophagous arthropods. Once in the bloodstream and during dissemination, the survival of these pathogens is dependent upon the ability of these bacteria to evade serum-borne host defenses until a proper cellular host is reached. Rickettsia conorii expresses an outer membrane protein, Adr1, which binds the complement inhibitory protein vitronectin to promote resistance to the anti-bacterial effects of the terminal complement complex...
2017: Frontiers in Cellular and Infection Microbiology
Michael G Gresock, Kathleen Postle
In Gram-negative bacteria, the cytoplasmic membrane protein TonB transmits energy derived from proton motive force to energize transport of important nutrients through TonB-dependent transporters in the outer membrane. Each transporter consists of a beta barrel domain and a lumen-occluding cork domain containing an essential sequence called the TonB box. To date, the only identified site of transporter-TonB interaction is between the TonB box and residues ∼158 to 162 of TonB. While the mechanism of ligand transport is a mystery, a current model based on site-directed spin labeling and molecular dynamics simulations is that, following ligand binding, the otherwise-sequestered TonB box extends into the periplasm for recognition by TonB, which mediates transport by pulling or twisting the cork...
May 15, 2017: Journal of Bacteriology
Georgios N Tsaousis, Stavros J Hamodrakas, Pantelis G Bagos
Transmembrane beta-barrels (TMBBs) constitute an important structural class of membrane proteins located in the outer membrane of gram-negative bacteria, and in the outer membrane of chloroplasts and mitochondria. They are involved in a wide variety of cellular functions and the prediction of their transmembrane topology, as well as their discrimination in newly sequenced genomes is of great importance as they are promising targets for antimicrobial drugs and vaccines. Several methods have been applied for the prediction of the transmembrane segments and the topology of beta barrel transmembrane proteins utilizing different algorithmic techniques...
2017: Methods in Molecular Biology
Wei Tian, Meishan Lin, Hammad Naveed, Jie Liang
Motivation: Transmembrane beta-barrel proteins (TMBs) serve a multitude of essential cellular functions in Gram-negative bacteria, mitochondria and chloroplasts. Transfer free energies (TFEs) of residues in the transmembrane (TM) region provides fundamental quantifications of thermodynamic stabilities of TMBs, which are important for the folding and the membrane insertion processes, and may help in understanding the structure-function relationship. However, experimental measurement of TFEs of TMBs is challenging...
June 1, 2017: Bioinformatics
Yoriko Lill, Lorne D Jordan, Chuck R Smallwood, Salete M Newton, Markus A Lill, Phillip E Klebba, Ken Ritchie
The important process of nutrient uptake in Escherichia coli, in many cases, involves transit of the nutrient through a class of beta-barrel proteins in the outer membrane known as TonB-dependent transporters (TBDTs) and requires interaction with the inner membrane protein TonB. Here we have imaged the mobility of the ferric enterobactin transporter FepA and TonB by tracking them in the membranes of live E. coli with single-molecule resolution at time-scales ranging from milliseconds to seconds. We employed simple simulations to model/analyze the lateral diffusion in the membranes of E...
2016: PloS One
Konstantinos D Tsirigos, Arne Elofsson, Pantelis G Bagos
MOTIVATION: The PRED-TMBB method is based on Hidden Markov Models and is capable of predicting the topology of beta-barrel outer membrane proteins and discriminate them from water-soluble ones. Here, we present an updated version of the method, PRED-TMBB2, with several newly developed features that improve its performance. The inclusion of a properly defined end state allows for better modeling of the beta-barrel domain, while different emission probabilities for the adjacent residues in strands are used to incorporate knowledge concerning the asymmetric amino acid distribution occurring there...
September 1, 2016: Bioinformatics
Martin Bommer, Ana-Nicoleta Bondar, Athina Zouni, Holger Dobbek, Holger Dau
In all organisms that employ oxygenic photosynthesis, the membrane-extrinsic PsbO protein is a functionally important component of photosystem II. To study the previously proposed proton antenna function of carboxylate clusters at the protein-water interface, we combined crystallography and simulations of a truncated cyanobacterial (Thermosynechococcus elongatus) PsbO without peripheral loops. We expressed the PsbO β-barrel heterologously and determined crystal structures at resolutions of 1.15-1.5 Å at 100 K at various pH values and at 297 K and pH 6...
August 23, 2016: Biochemistry
Leonie van 't Hag, Hsin-Hui Shen, Tsung-Wu Lin, Sally L Gras, Calum J Drummond, Charlotte E Conn
A fundamental understanding of the effect of amphiphilic protein encapsulation on the nanostructure of the bicontinuous cubic phase is crucial to progressing biomedical and biological applications of these hybrid protein-lipid materials, including as drug delivery vehicles, as biosensors, biofuel cells and for in meso crystallization. The relationship between the lipid nanomaterial and the encapsulated protein, however, remains poorly understood. In this study, we investigated the effect of incorporating the five transmembrane and lipo-proteins which make up the β-barrel assembly machinery from Gram-negative bacteria within a series of bicontinuous cubic phases...
November 29, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
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