Crystal Structure of the Monomeric Porin OmpG

Subbarao, G.V.; Berg, Bert van den

doi:10.1016/j.jmb.2006.05.045

Cited by 102 publications

(113 citation statements)

References 39 publications

Supporting

Mentioning

105

Contrasting

Order By: Relevance

“…This is consistent with the facts that TolC, the OprM homologue of E. coli (7) and most outer membrane porins form a trimer (3,17). However, OmpG, the outer membrane porin of E. coli has been demonstrated to be a monomeric protein (20,22). Therefore, it is anticipated that proteins with different oligomeric states may exist in the outer membrane.…”

Section: Oligomeric Structures Of Oprm Oprj and Oprn Reconstituted supporting

confidence: 86%

Diversity in the Oligomeric Channel Structure of the Multidrug Efflux Pumps in Pseudomonas aeruginosa

Yoshihara

Eda

2007

Microbiology and Immunology

View full text Add to dashboard Cite

MexAB‐OprM, the multidrug efflux pump of Pseudomonas aeruginosa, contributes to the high resistance of this organism to a wide variety of antibiotics. To investigate the structure and function of OprM, the outer membrane channel of MexAB‐OprM, we examined the oligomeric states of OprM and its homologues OprJ and OprN. These proteins were treated with crosslinking reagent after their reconstitution into liposome membranes. The crosslinked products indicated that OprM and OprN formed trimers, while OprJ unexpectedly appeared to form a tetramer. In order to test whether differences in oligomeric structure might be intimately related to channel function, we examined the channel‐forming activity of these proteins by liposome swelling assay. However, no significant differences in channel characteristics were detected among OprM, OprJ, and OprN. We proposed the probable explanation for the diversity in the oligomeric structure of the channel proteins.

show abstract

Section: Oligomeric Structures Of Oprm Oprj and Oprn Reconstituted supporting

confidence: 86%

Diversity in the Oligomeric Channel Structure of the Multidrug Efflux Pumps in Pseudomonas aeruginosa

Yoshihara

Eda

2007

Microbiology and Immunology

View full text Add to dashboard Cite

show abstract

“…The average inclination of the ␤-strands relative to the barrel axis is 37°, varies between 27 and 46°, and forms a barrel of almost circular shape (see Fig. 2F), similar, e.g., to the monomeric porin OmpG (25,26).…”

Section: Resultsmentioning

confidence: 97%

Structure of the human voltage-dependent anion channel

Bayrhuber

Meins

Habeck

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

520

626

View full text Add to dashboard Cite

The voltage-dependent anion channel (VDAC), also known as mitochondrial porin, is the most abundant protein in the mitochondrial outer membrane (MOM). VDAC is the channel known to guide the metabolic flux across the MOM and plays a key role in mitochondrially induced apoptosis. Here, we present the 3D structure of human VDAC1, which was solved conjointly by NMR spectroscopy and x-ray crystallography. Human VDAC1 (hVDAC1) adopts a ␤-barrel architecture composed of 19 ␤-strands with an ␣-helix located horizontally midway within the pore. Bioinformatic analysis indicates that this channel architecture is common to all VDAC proteins and is adopted by the general import pore TOM40 of mammals, which is also located in the MOM.T he outer membrane of mitochondria (MOM) contains three integral membrane protein families, two of which form channels as part of larger protein complexes (for review, see ref. 1). These two MOM complexes, the general import pore TOM and the SAM insertase, allow for the entire translocation and insertion of nearly all newly synthesized proteins destined to the mitochondrial organelle (2, 3). The third protein family of typically high abundance (Ϸ10,000 copies per mitochondrion) is termed voltage-dependent anion channels (VDACs), because of the voltage sensitivity of its open probability (4, 5). Together, this small number of protein families is sufficient for full communication between mitochondria with their cellular environment (1).The VDAC channel was initially described as being reminiscent of bacterial porins and primarily responsible for the exchange of chemical energy equivalents between the cytosol and the mitochondrion (4, 6). Indeed, a variety of structural features (like barrel geometry and dimension) known from the bacterial precursors are maintained (7,8). By contrast, a variety of functions have been ascribed to the VDAC isoforms among which the direct coupling of the mitochondrial matrix to the energy maintenance of the cytosol seems to be the most general function (9). The structure of VDAC is of interest because of a substantial body of evidence connecting VDAC to apoptosis. It is suggested that VDAC is a critical player in the release of apoptogenic factors from mitochondria of mammalian cells, and consequently several hypotheses describing the mechanism of mitochondria-mediated apoptosis involving VDAC have been proposed (for review, see ref. 10). Results and DiscussionStructure Determination of hVDAC1: Combining NMR Spectroscopy and X-Ray Crystallography. In a parallel structural biology approach, we set out to characterize the structure of hVDAC1, the major isoform of this channel in mammalian tissues, by a combination of NMR spectroscopy and x-ray crystallography. The idea behind this project was to gain complementary structural information to have a solid basis for future studies, e.g., analysis of protein heterocomplex formation by NMR and crystal structures as a basis for drug target design. Only information derived from both methods and the application of an iterative s...

show abstract

“…To date, there are six NMR solution structures of b-barrel membrane proteins [1][2][3][4][5][6] (compared to the 89 unique b-barrel structures deposited in the Protein Data Bank), all except for OprH have corresponding X-ray crystal structures. [7][8][9][10][11][12] The first b-barrel membrane protein structure determined with solution NMR was in 2001 4 and the latest structure was determined in 2011 3 yielding an average of 0.6 structures a year. The dearth of solution NMR membrane protein structures is likely due to the difficulty of obtaining quality NMR spectra, which interferes with assigning the resonances and obtaining quality structural restraints.…”

Section: Introductionmentioning

confidence: 99%

Solution NMR resonance assignment strategies for β‐barrel membrane proteins

Fox

Columbus

2013

Protein Science

View full text Add to dashboard Cite

Membrane proteins in detergent micelles are large and dynamic complexes that present challenges for solution NMR investigations such as spectral overlap and line broadening. In this study, multiple methods are introduced to facilitate resonance assignment of b-barrel membrane proteins using Opa 60 from Neisseria gonorrhoeae as a model system. Opa 60 is an eight-stranded b-barrel with long extracellular loops (~63% of the protein) that engage host receptors and induce engulfment of the bacterium. The NMR spectra of Opa 60 in detergent micelles exhibits significant spectral overlap and resonances corresponding to the loop regions had variable line widths, which interfered with a complete assignment of the protein. To assign the b-barrel residues, trypsin cleavage was used to remove much of the extracellular loops while preserving the detergent solubilized b-barrel. The removal of the loop resonances significantly improved the assignment of the Opa 60 b-barrel region (97% of the resonances corresponding to the b-barrel and periplasmic turns were assigned). For the loop resonance assignments, two strategies were implemented; modulating temperature and synthetic peptides. Lowering the temperature broadened many peaks beyond detection and simplified the spectra to only the most dynamic regions of the loops facilitating 27 loop resonances to be assigned. To further assign functionally important and unstructured regions of the extracellular loops, a synthetic 20 amino acid peptide was synthesized and had nearly complete spectral overlap with the full-length protein allowing 17 loop resonances to be assigned. Collectively, these strategies are effective tools that may accelerate solution NMR structure determination of b-barrel membrane proteins.

show abstract

Crystal Structure of the Monomeric Porin OmpG

Cited by 102 publications

References 39 publications

Diversity in the Oligomeric Channel Structure of the Multidrug Efflux Pumps in Pseudomonas aeruginosa

Diversity in the Oligomeric Channel Structure of the Multidrug Efflux Pumps in Pseudomonas aeruginosa

Structure of the human voltage-dependent anion channel

Solution NMR resonance assignment strategies for β‐barrel membrane proteins

Contact Info

Product

Resources

About