OmpA protein

Figure 2.7. The outer membrane of Gram-negative bacteria. Abbreviations LB, LamB protein LP, lipoprotein O, OmpA protein MP, membrane protein. The peptidoglycan backbone consists of alternating residues of A-acetylglucosamine and /V-acetylmuramic acid, which are cross-linked via short peptides.

About 105 copies per cell of the previously mentioned (Section C,2) larger 325-residue structural protein, OmpA protein,350 after its gene symbol ompA... 

Sugawara, E., and Nikaido, H. (1994). OmpA protein of Escherichia coli outer membrane occurs in open and closed channel forms./ Biol. Chem. 269, 17981-17987. 

Overexpression of apoaequorin (Inouye et al., 1989, 1991). To produce a large quantity of apoaequorin, an apoaequorin expression plasmid piP-HE containing the signal peptide coding sequence of the outer membrane protein A (ompA) of E. coli (Fig. 4.1.12) was constructed and expressed in E. coli. The expressed apoaequorin was secreted into the periplasmic space of bacterial cells and culture medium. The cleaving of ompA took place during secretion thus the... 

E. coli, like other Gram-negative bacteria, has an outer membrane which hampers excretion of proteins to the culture media. Thus, expressed proteins can remain in the cytoplasm or can be directed into the periplasm employing the N-terminus fusion of a signal peptide (e.g. OmpA, pelB, OmpF, PhoA, Tat signal peptides) [30]. 

Requirements for Protein Translocation across a Membrane The secreted bacterial protein OmpA has a precursor, ProOmpA, which has the amino-terminal signal sequence required for secretion. If purified ProOmpA is denatured with 8 M urea and the urea is then removed (such as... 

The most abundant protein in the E. coli outer membrane is OmpA. It appears to form a transmembrane helical bundle. Although it is regarded primarily as a structural protein it too acts, in monomeric form, as an inefficient diffusion pore.350 Mitochondrial outer membranes contain nonspecific pores (mitochondrial porins) that allow passage of sucrose and other saccharides of molecular mass up to 2 to 8 kDa.351 352 Similar pore-forming proteins have been found in plant peroxisomes.353... 

The targeting of antibodies to the periplasm requires the use of signal peptides. The pelB leader of the pectate lyase gene of Erwinia carotovora (56) is commonly used. The gill leader (9), the phoA leader of the E. coli alkaline phosphatase, and the ompA leader of E. coli outer membrane protein OmpA have also been used, being common to many protein expression vectors (57,58). Further examples are the heat-stable enterotoxin II (stll) signal sequence (47) and the bacterial chloramphenicol acetyltransferase (cat) leader (59). 

Figure 6.5 Requirement for the presence of detergent while screening micelle-solubilized membrane proteins. In this series of experiments both the target (KcsA) and the reference (OmpA) were immobilized at a solution equivalent of 150pM. The histogram represents the fractional difference in peak amplitude of a known ligand of KcsA in the presence of KcsA and OmpA. The bar labeled control represents the first application of the ligand. Subsequently three injections of the ligand were performed using buffers that contained no detergent. A further three injections were performed where the buffer used to wash the immobilized samples contained deuterated DPC.

Hobom G, Arnold N, Ruppert A, OmpA fusion proteins for presentation of foreign antigens on the bacterial outer membrane, Dev. Biol. Stand., 84 255-262, 1995. 

Freudl R, MacIntyre S, Degen M, Henning U, Cell surface exposure of the outer membrane protein OmpA of Escherichia coli K-12, J. Mol. Biol., 188 491 494, 1986. 

The vector for protein expression in the periplasmic space of E. coli (3) (Fig. 1) contains a lac promotor, which can be induced with IPTG (Isopropyl-D-thiogalacto-pyranoside). Translation starts with the OmpA signal sequence of the outer membrane protein A of E. coli, followed by the chemokine cDNA. The signal sequence leads to protein secretion into the periplasm, where it is cleaved off by bacterial enzymes. The periplasmic space has an oxidizing milieu, which enables disulfide bond formation and contains molecular chaperones, which inhibit aggregation and support correct folding of proteins (8). The lysis of the periplasmic space is performed by four freeze/thaw cycles,... 

Fig. 1. Vector for protein expression in the periplasmic space of E. coli. Expression is controlled by an IPTG inducable lac promotor. SD is the Shine-Dalgamo sequence, OmpA is the signal sequence of the outer membrane protein A of E. coli followed by the RANTES cDNA.

Fernandez, C., Hilty, C., Bonjour, S., Adeishvili, K., Pervushin, K., and Wuthrich, K. (2001b). Solution NMR studies of the integral membrane proteins OmpX and OmpA from Escherichia coli. FEBS Lett. 504, 173-178. 

Koebnik, R. (1999). Structural and functional roles of the surface-exposed loops of the /3-barrel membrane protein OmpA from Escherichia coli.J. Baderiol. 181, 3688-3694. 

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