Faculty Opinions recommendation of Identification of an outer membrane protein required for the transport of lipopolysaccharide to the bacterial cell surface.

2004 ◽  
Author(s):  
Tracy Raivio
Keyword(s):  
Membrane Protein ◽  
Cell Surface ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Bacterial Cell ◽  
Bacterial Cell Surface

scholarly journals Activation of the Complement Classical Pathway (C1q Binding) by Mesophilic Aeromonas hydrophila Outer Membrane Protein

1998 ◽  
Vol 66 (8) ◽  
pp. 3825-3831 ◽  
Author(s):  
Susana Merino ◽  
Maria Mercedes Nogueras ◽  
Alicia Aguilar ◽  
Xavier Rubires ◽  
Sebastian Albertí ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Cell Surface ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Hemolytic Activity ◽  
Aeromonas Hydrophila ◽  
Bacterial Cell ◽  
Classical Pathway ◽  
Independent Manner ◽  
Bacterial Outer Membrane

ABSTRACT The mechanism of killing of Aeromonas hydrophilaserum-sensitive strains in nonimmune serum by the complement classical pathway has been studied. The bacterial cell surface component that binds C1q more efficiently was identified as a major outer membrane protein of 39 kDa, presumably the porin II described by D. Jeanteur, N. Gletsu, F. Pattus, and J. T. Buckley (Mol. Microbiol. 6:3355–3363, 1992), of these microorganisms. We have demonstrated that the purified form of porin II binds C1q and activates the classical pathway in an antibody-independent manner, with the subsequent consumption of C4 and reduction of the serum total hemolytic activity. Activation of the classical pathway has been observed in human nonimmune serum and agammaglobulinemic serum (both depleted of factor D). Binding of C1q to other components of the bacterial outer membrane, in particular to rough lipopolysaccharide, could not be demonstrated. Activation of the classical pathway by this lipopolysaccharide was also much less efficient than activation by the outer membrane protein. The strains possessing O-antigen lipopolysaccharide bind less C1q than the serum-sensitive strains, because the outer membrane protein is less accessible, and are resistant to complement-mediated killing. Finally, a similar or identical outer membrane protein (presumably porin II) that binds C1q was shown to be present in strains from the most common mesophilic Aeromonas O serogroups.

scholarly journals Physiological Characterization of SusG, an Outer Membrane Protein Essential for Starch Utilization byBacteroides thetaiotaomicron

1999 ◽  
Vol 181 (23) ◽  
pp. 7206-7211 ◽  
Author(s):  
Joseph A. Shipman ◽  
Kyu Hong Cho ◽  
Hilary A. Siegel ◽  
Abigail A. Salyers
Keyword(s):  
Membrane Protein ◽  
Cell Surface ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Main Role ◽  
Binding Assays ◽  
Bacterial Surface ◽  
Physiological Characterization ◽  
Starch Utilization

ABSTRACT Results from previous studies had suggested that Bacteroides thetaiotaomicron utilizes starch by binding the polysaccharide to the bacterial surface and subsequently degrading the polymer by using cell-associated enzymes. Most of the starch-degrading activity was localized to the periplasm, but a portion appeared to be membrane associated. This raised the possibility that some breakdown might occur in the outer membrane prior to exposure of the polysaccharide to the periplasmic polysaccharide-degrading enzymes. In this study, we show that SusG, an outer membrane protein which has been shown genetically to be essential for starch utilization, has enzymatic activity. Results of protease accessibility experiments support the hypothesis that SusG is exposed on the cell surface. Results of [14C]starch binding assays, however, show that SusG plays a negligible role in binding of starch to the cell surface. Consistent with this, SusG has a relatively high Km for starch and by itself is not sufficient to allow cells to grow on starch or to bind starch. Hence, the main role of SusG is to hydrolyze starch, but the binding of starch to the cell surface is evidently mediated by other proteins presumably interacting with SusG.

scholarly journals Structural Characterization of the Lactoferrin Receptor from Neisseria meningitidis

1999 ◽  
Vol 181 (14) ◽  
pp. 4417-4419 ◽  
Author(s):  
Thorsten Prinz ◽  
Markus Meyer ◽  
Annika Pettersson ◽  
Jan Tommassen
Keyword(s):  
Membrane Protein ◽  
Cell Surface ◽  
Neisseria Meningitidis ◽  
Outer Membrane ◽  
Structural Characterization ◽  
Outer Membrane Protein ◽  
Lactoferrin Receptor ◽  
Topology Model

ABSTRACT The meningococcal lactoferrin receptor is composed of the integral outer membrane protein LbpA and the peripheral lipoprotein LbpB. Homooligomeric complexes of LbpA and heterooligomers consisting of LbpA and LbpB were identified. Furthermore, five cell surface-exposed loops of LbpA were identified, which partially confirms a previously proposed topology model.

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