scholarly journals Biochemical Analysis of Interactions between Outer Membrane Proteins That Contribute to Starch Utilization byBacteroides thetaiotaomicron

2001 ◽  
Vol 183 (24) ◽  
pp. 7224-7230 ◽  
Author(s):  
Kyu Hong Cho ◽  
Abigail A. Salyers
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Gel Electrophoresis ◽  
Biochemical Analysis ◽  
Outer Membrane Proteins ◽  
Proteinase K ◽  
Cross Linking ◽  
Early Step ◽  
Bacterial Surface ◽  
Starch Utilization

ABSTRACT An early step in the utilization of starch by Bacteroides thetaiotaomicron is the binding of starch to the bacterial surface. Four starch-associated outer membrane proteins of B. thetaiotaomicron that have no starch-degrading activity have been identified. Two of these, SusC and SusD, have been shown by genetic analysis to be required for starch binding. In this study, we provide the first biochemical evidence that these two proteins interact physically with each other. Both formaldehyde cross-linking and nondenaturing gel electrophoresis experiments showed that SusC and SusD interact to form a complex. Two other proteins encoded by genes in the same operon, SusE and SusF, proved not to be essential for starch utilization and actually decreased starch binding when they were present along with SusC and SusD. Consistent with this, nondenaturing gel analysis revealed that in a strain producing SusC, SusD, and SusE, the SusCD complex was partially destabilized. The strain producing SusC, SusD, and SusE also grew more slowly on starch than a strain producing SusC, SusD, SusE, and SusF (μmax, 0.29 and 0.37/h, respectively). Thus, SusE appears to interact with the SusCD complex. SusE also interacts with SusF, because SusE was less susceptible to proteinase K digestion when SusF was present, and nondenaturing gel analysis detected a complex formed by these two proteins. Our results indicate that SusC, SusD, SusE, and SusF form a protein complex in the outer membrane but that SusE and SusF are dispensable members of this complex.

Outer membrane proteins from Serratia marcescens

1993 ◽  
Vol 39 (1) ◽  
pp. 108-111 ◽  
Author(s):  
Marta Puig ◽  
Carme Fusté ◽  
Miquel Viñas
Keyword(s):  
Membrane Proteins ◽  
Serratia Marcescens ◽  
Outer Membrane ◽  
Nutrient Availability ◽  
Sodium Dodecyl Sulphate ◽  
Gel Electrophoresis ◽  
Outer Membrane Proteins ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Cultural Conditions

The outer membrane proteins (OMPs) of several strains of Serratia marcescens have been studied by sodium dodecyl sulphate – urea – polyacrylamide gel electrophoresis. Four major OMPs, named Omp1, Omp2, Omp3, and OmpA (42, 40, 39, and 37 kDa, respectively), have been visualized. The relative proportions of Omp2 and Omp3 depend on cultural conditions (temperature of incubation, osmolarity, and nutrient availability).Key words: Serratia marcescens, outer membrane proteins, porin.

Identification of Campylobacter jejuni and C. coli by gel electrophoresis of the outer membrane proteins.

1989 ◽  
Vol 27 (5) ◽  
pp. 1072-1076 ◽  
Author(s):  
I Derclaye ◽  
I Delor ◽  
M Van Bouchaute ◽  
P Moureau ◽  
G Wauters ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Campylobacter Jejuni ◽  
Gel Electrophoresis ◽  
Outer Membrane Proteins

scholarly journals Surface Immunolabeling and Consensus Computational Framework To Identify Candidate Rare Outer Membrane Proteins of Treponema pallidum

2010 ◽  
Vol 78 (12) ◽  
pp. 5178-5194 ◽  
Author(s):  
David L. Cox ◽  
Amit Luthra ◽  
Star Dunham-Ems ◽  
Daniel C. Desrosiers ◽  
Juan C. Salazar ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Treponema Pallidum ◽  
Immunoblot Analysis ◽  
Proteinase K ◽  
Membrane Proteome ◽  
Computational Framework ◽  
Shifting Balance ◽  
Dual Label

ABSTRACT Treponema pallidum reacts poorly with the antibodies present in rabbit and human syphilitic sera, a property attributed to the paucity of proteins in its outer membrane. To better understand the basis for the syphilis spirochete's “stealth pathogenicity,” we used a dual-label, 3-step amplified assay in which treponemes encapsulated in gel microdroplets were probed with syphilitic sera in parallel with anti-FlaA antibodies. A small (approximately 5 to 10%) but reproducible fraction of intact treponemes bound IgG and/or IgM antibodies. Three lines of evidence supported the notion that the surface antigens were likely β-barrel-forming outer membrane proteins (OMPs): (i) surface labeling with anti-lipoidal (VDRL) antibodies was not observed, (ii) immunoblot analysis confirmed prior results showing that T. pallidum glycolipids are not immunoreactive, and (iii) labeling of intact organisms was not appreciably affected by proteinase K (PK) treatment. With this method, we also demonstrate that TprK (TP0897), an extensively studied candidate OMP, and TP0136, a lipoprotein recently reported to be surface exposed, are both periplasmic. Consistent with the immunolabeling studies, TprK was also found to lack amphiphilicity, a characteristic property of β-barrel-forming proteins. Using a consensus computational framework that combined subcellular localization and β-barrel structural prediction tools, we generated ranked groups of candidate rare OMPs, the predicted T. pallidum outer membrane proteome (OMPeome), which we postulate includes the surface-exposed molecules detected by our enhanced gel microdroplet assay. In addition to underscoring the syphilis spirochete's remarkably poor surface antigenicity, our findings help to explain the complex and shifting balance between pathogen and host defenses that characterizes syphilitic infection.

scholarly journals Assembly of TolC, a Structurally Unique and Multifunctional Outer Membrane Protein of Escherichia coli K-12

2003 ◽  
Vol 185 (22) ◽  
pp. 6540-6547 ◽  
Author(s):  
John Werner ◽  
Anne Marie Augustus ◽  
Rajeev Misra
Keyword(s):  
Escherichia Coli ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Outer Membrane Proteins ◽  
The Other ◽  
Proteinase K ◽  
Folded Structure ◽  
K 12

ABSTRACT TolC is a multifunctional outer membrane protein of Escherichia coli that folds into a novel α-β-barrel conformation absent in the other model outer membrane proteins used in assembly studies. The data presented in this work show that the unique folded structure of TolC reflects a unique assembly pathway. During its assembly, the newly translocated nascent TolC monomers are released in the periplasm. Maturation of these nascent monomers, and possibly their oligomerization, in the periplasm precedes their insertion in the outer membrane. The completion of the assembly process is signaled by the development of a characteristic proteinase K-resistant fragment generated by cleavage at a single, periplasmically exposed, protease-sensitive site of the membrane-anchored trimer. None of the assembly steps of TolC is affected by known folding factors, such as SurA, Skp, and lipopolysaccharide, which have profound effects on the assembly of other model trimeric outer membrane proteins. Two assembly-defective TolC mutants were isolated and characterized. One of the mutants (TolCI106N) was defective in the folding of nascent monomers, while the other (TolCS350F) was impaired in steps involving trimerization and membrane insertion of folded monomers.

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