SDS POLYACRYLAMIDE GEL ELECTROPHORESIS PATTERNS OF THE OUTER MEMBRANE PROTEINS FROM E. COLI STRAINS OF DIFFERENT PATHOGENIC ORIGIN

Outer membrane proteins of bovine Pasteurella multocida serogroup A isolates

The outer membrane proteins (OMPs) of P. multocida serotypes A3 (7 isolates), A4 (2 isolates), A3,4 and A2 (one isolate each) obtained from pneumonic cattle (10 isolates) and from one pig isolate were investigated to identify potential immunogens. SDS-PAGE of P. multocida OM isolated by SDG centrifugation of spheroplasts revealed eight major OMPs. Outer membranes isolated by sarcosyl extraction or SDG had similar protein composition on Coomassie blue-stained SDS-PA gel and on immunoblots. Two major OMPs (M(r)s of 35 and 46 kDa at 100 degrees C) demonstrated heat modifiability with apparent M(r)s of 30 and 34 kDa at 37 degrees C, respectively. The N-terminal aa sequences of these heat modifiable proteins revealed homology with E. coli OmpA and Hib P1 proteins, respectively. Protease treatment of whole cells followed by western immunoblots using bovine convalescent sera identified several immunogenic, surface-exposed and conserved OMPs among the eleven P. multocida isolates examined. The whole organism SDS-PAGE profiles of the eleven P. multocida isolates differed such that six patterns were seen. These patterns could potentially be used as a typing system for P. multocida bovine isolates based on the molecular weights of whole cell proteins. The above observations have potentially important implications relative to the immunity to infection.

Nuclear-magnetic-resonance analysis of the capsular antigen of Actinobacillus pleuropneumoniae serotype 9. Its identity with the capsular antigen of Escherichia coli K62 (K2ab), Neisseria meningitidis serogroup H and Pasteurella haemolytica serotype T15

The specific capsular antigen of Actinobacillus pleuropneumoniae serotype 9 was characterized by one-dimensional and two-dimensional high-field nuclear-magnetic-resonance methods, and by chemical analyses, as a teichoic-acid-type polymer of a repeating unit having the structure [formula: see text] The basic polymer structure is identical to capsular antigens of Neisseria meningitidis group H, Escherichia coli K62 (K2ab) and Pasteurella haemolytica serotype T15.

Outer membrane proteins of E. coli in the host-pathogen interaction in urinary tract infection

Outer membrane protein patterns (Omp) of Escherichia coli obtained directly from the urine of bacteriuric patients without passage on artificial culture media (ACM) were studied by polyacrylamide gel electrophoresis (SDS-PAGE) in an effort to determine whether in vivo conditions of growth affected the expression of these bacterial surface structures. Seventeen strains studied showed two distinct Omp patterns: one protein band appeared at the level of porin proteins (40 kDa) in both patterns, but Omp A protein was at the level of 36 kDa in the first pattern and a new protein was observed at 21.5 kDa in the second pattern suggesting that it is a fragment of Omp A. High molecular weight proteins were also observed in most of the strains and this finding was related to lack of free iron when the same strains were grown under iron restricted conditions in vitro. The same strains grown in pooled urine from normal females showed the first pattern mentioned above. Comparative growth on ACM of urinary strains and E. coli strains isolated from blood, feces and wounds showed an increase in the number of porins expressed (from 1 to 2 or 3, with some variability observed between strains). Differences in osmolality between pooled urine and ACM used, plus in vitro studies varying the osmolality of culture media, showed that osmolality accounted for differences in the number of porins expressed: porin expression decreased in urine the ACM of high osmolality, suggesting that the same phenomena occurred in vivo. It is concluded that host factors including low availability of iron and high osmolality present in the urinary tract influence the expression of several E. coli surface proteins. These proteins may relate to the ability of E. coli to colonize and invade the urinary tract by regulating the physiologic and/or metabolic state of the bacterial cell favoring survival of the organism in a hostile environment. Specific immune responses directed against porins could influence the outcome of this host-parasite interaction.

Comparative structural elucidation of the K18, K22, and K100 antigens of Escherichia coli as related ribosyl-ribitol phosphates

The structures of the capsular K18, K22, and K100 antigens of E. coli O23:K18:H15, O23:K22:H15, and O75:K100:H5, respectively, were elucidated by determination of composition, 1H-, 13C-, and 31P-n.m.r. spectroscopy, periodate oxidation, alkaline hydrolysis followed by incubation with alkaline phosphatase, and methylation analysis of the polymers and their neutral fragmentation products. The polymers are poly(ribosyl-ribitol phosphates) related to the capsular antigen of H. influenzae (Hib). The K22 antigen has the repeating unit -P-2)-beta-Rib-(1----2)-RibOH-(5-, and the K18 antigen has the same polymer chain with partial 3-O-acetylation of the ribose moiety. The K100 antigen consists of repeating units of -P-3)-beta-Rib-(1----2)-RibOH-(5- and seems to have a secondary structure different from that of the other antigens. Together with the Hib capsular antigens, the structure of which was reported as -P-3)-beta-Rib-(1----1)-RibOH-(5-, these capsular antigens represent a structurally related group of capsular polymers.

Comparison of the exoproducts of gram-negative bacteria by SDS-Page

The protein exoproducts released during exponential growth of Gram-negative bacteria were analysed and compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-Page). The following bacterial strains were tested: Escherichia coli, Klebsiella pneumoniae, Citrobacter freundii, Enterobacter cloacae, Serratia liquefaciens, Serratia rubidaea, Proteus mirabilis, Proteus vulgaris, Salmonella minnesota, Pseudomonas aeruginosa and Pseudomonas fluorescens. It is demonstrated by SDS-Page that members of one species show identical protein pattern, whereas different species show besides comparable protein bands a species characteristic pattern. All members of Enterobacteriaceae were shown to release proteins whose molecular weights fell into the following size regions: Each strain was shown to synthesize a polypeptide of molecular weight 34,000 and one or more polypeptides within the molecular weight range 25,000-29,000. This profile was shown to be clearly different from that of Pseudomonas strains where 20 or more distinct polypeptides ranging from 12,500 to 160,000 Mr were detectable.

Comparison of sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles and antigenic relatedness among outer membrane proteins of 49 Brucella abortus strains

Outer membrane proteins were solubilized from 49 strains of Brucella abortus by sequential extraction of physically disrupted cells with N-lauroylsarcosinate and a dipolar ionic detergent (Verstreate et al., Infect. Immun. 35:979-989, 1982). The strains tested included standard agglutination test strain 1119, virulent strain 2308, and eight reference strains representing each of the biotypes; the remainder were isolates from cattle in North America with natural infections and included biotypes 1, 2, and 4. Three principal protein groups with apparent molecular weights of 88,000 to 94,000 (group 1), 35,000 to 40,000 (group 2, now established as porins [Douglas et al., Infect. Immun. 44:16-21, 1984]), and 25,000 to 30,000 (group 3) were observed in every strain. Some variability in banding patterns occurred among strains, but intrastrain variation was sufficient to preclude the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles of outer membrane proteins for differentiating among strains of B. abortus. One antigen ([b]) was shared among the porin proteins, and three others ([c], ([d], and ([ e]) were shared among the group 3 proteins of all of the strains tested, indicating that these relationships are probably species wide. These results suggest that it may be possible to use outer membrane proteins from a representative strain of B. abortus in a vaccine for species-wide immunization.

Outer membrane protein K of Escherichia coli: purification and pore-forming properties in lipid bilayer membranes

Protein K, a recently described outer membrane protein correlated with encapsulation in Escherichia coli (Paakkanen et al., J. Bacteriol. 139:835-841, 1979), has been purified to apparent homogeneity. Purification was based upon the noncovalent association of protein K with peptidoglycan, and the purified protein was shown to form sodium dodecyl sulfate-resistant oligomers on polyacrylamide gels. Incorporation of small amounts (10(-10) to 10(-11) M) of purified protein K into artificial lipid bilayers resulted in an increase, by many orders of magnitude, in membrane conductance. The increased conductance resulted from the formation of large, water-filled, ion-permeable channels exhibiting single-channel conductance in 1.0 M KCl of 1.83 nS. The membrane conductance showed a linear relationship between current and applied voltage and was not voltage induced or regulated. The channel was permeable to large organic ions (e.g., Tris+ Cl-) and, based upon a pore length of 7.5 nm, a minimum channel diameter of 1.2 nm was estimated; these properties resemble values for other enteric porins. The possible biological role of the pores produced by protein K is discussed.