Purification and properties of an aminopeptidase fromTreponema phagedenis (Reiter strain)

An aminopeptidase was highly purified from a cellular extract ofTreponema phagedenis (Reiter strain) by ammonium sulfate precipitation and successive chromatography on Sepharose 6B, DEAE-Sepharose CL-6B and CM-Sepharose CL-6B. The molecular weight of the enzyme was 74,500. The enzyme was stable in the pH region 5.0–7.0 and up to 50°C. The optimal pH, ionic strength, and temperature were pH 7.9–8.0,I 0.13, and 37°C, respectively. Co²⁺ was essential for the enzyme activity with an optimal concentration of 0.3 mM, and EDTA and such divalent cations as Hg²⁺, Cu²⁺, Zn²⁺, Pb²⁺, Sn²⁺, and Cd²⁺ were inhibitory against the Co²⁺-activated enzyme. The enzyme exhibited a preference for hydrophobic residues as well as Arg in the N-terminal position and cleaved in the order of Tyr > Trp > Phe > Leu > Arg > Ala His, Met, and Ser, but did not cleave the other amino acids including Pro, Glu, Asp, and Lys.     

Pyruvate oxidation by the Reiter strain of Treponema phagedenis.

Spectrophotometric assays of pyruvate oxidation catalyzed by extracts of the Reiter strain of Treponema phagedenis indicated that viologen dyes, flavin nucleotides, and a ferric iron chelate, but not pyridine nucleotides, were utilized as electron acceptors. Benzyl viologen-linked activity partially sedimented during ultracentrifugation and appeared similar to clostridial pyruvate:ferredoxin oxidoreductase with respect to the spectral properties of the enzyme chromophore. Electron carrier activity in treponemal extracts was quantitated by a metronidazole-linked assay in which the oxidation of pyruvate by carrier-depleted extracts led to the reduction of electron carrier in the crude extracts which then reduced metronidazole. The rate of metronidazole reduction was proportional to the amount of electron carrier present in the assay. Electron carrier activity in Triton X-100-solubilized, crude extracts partially purified by DEAE-cellulose chromatography and gel filtration was attributed to a protein possessing the spectral and physical properties of a ferredoxin. A similar protein appeared to be present in extracts of Treponema denticola ST10.     

Fumarate reduction and product formation by the Reiter strain of Treponema phagedenis.

The catabolic pathways for butyrate, acetate, succinate, and ethanol formation by the Reiter strain of Treponema phagedenis were investigated. Enzyme activities were demonstrated for glucose catabolism to pyruvate by the Embden-Meyerhof-Parnas pathway. Butyrate formation from acetyl-coenzyme A (acetyl-CoA) does not generate ATP by substrate level phosphorylation and involves NAD+-dependent 3-hydroxybutyryl-CoA dehydrogenase and NAD(P)+-independent butyryl-CoA dehydrogenase activities. Butyrate is formed from butyryl-CoA in a CoA transphorase reaction. Phosphate acetyltransferase and acetate kinase activities convert acetyl-CoA to acetate. An NADP+-dependent alcohol dehydrogenase participates in ethanol formation; however, the manner in which acetyl-CoA is reduced to acetaldehyde is unclear. A membrane-associated fumarate reductase was found which utilized reduced ferredoxin or flavin nucleotides as physiological electron donors. Additional electron carriers may also be involved in electron transfer for fumarate reduction. Strains of Treponema denticola, T. vincentii, and T. minutum utilized fumarate without succinate formation, whereas strains of T. phagedenis and T. refringens formed succinate from exogenously supplied fumarate.     

Purification and Characterization of Axial Filaments from Treponema phagedenis Biotype reiterii (the Reiter Treponeme)

Axial filaments have been purified from Treponema phagedenis biotype reiterii (the Reiter treponeme) and partially characterized chemically. The preparations consist largely of protein but also contain small amounts of hexose (3%). Filaments dissociate to subunits in acid, alkali, urea, guanidine, and various detergents. Amino acid analyses show an overall resemblance to other spirochetal axial filaments and to bacterial flagella. Dissociated filaments migrate as a single band upon acrylamide gel electrophoresis at pH 4.3 (in 4 M urea and 10 (3) M ethylenediaminetetraacetate) and at pH 12, but in sodium dodecyl sulfate gels, three bands are obtained under a wide variety of conditions. Two of these bands migrate very close together, with molecular weights of 33,000 +/- 500. The other band has a molecular weight of 36,500 +/- 500. Analysis of axial filaments by the dansyl chloride method yields both methionine and glutamic acid as amino terminal end groups. Sedimentation equilibrium measurements on dissociated axial filaments in 7 M guanidine hydrochloride yield plots of log C against varkappa(2) which vary with the speed and initial protein concentration used. Molecular weight values calculated from these plots are consistent with a model in which axial filament subunits are heterogeneous with respect to molecular weight in the approximate range of 32,000 to 36,000.     

Correlation of treponemicidal activity in normal human serum with the presence of IgG antibody directed against polypeptides of Treponema phagedenis biotype Reiter and Treponema pallidum, Nichols strain

Normal human serum (NHS) was shown to have complement-dependent treponemicidal activity against both Treponema pallidum and Treponema phagedenis biotype Reiter (TPR) by employing in vitro-in vivo neutralization and TPR plaque assays, respectively. The molecular basis of NHS treponemicidal activity was studied by immunoblot analysis in conjunction with treponemicidal assays. Five major T. pallidum polypeptide bands (47kDa, 35kDa, 33kDa doublet, and 30 kDa) and three major TPR polypeptide bands (47kDa and 33kDa doublet) bound IgG present in NHS. Absorption of NHS with TPR completely removed both TPR and T. pallidum treponemicidal activity; corresponding immunoblots demonstrated a significant removal of IgG antibody against all three TPR polypeptide bands as well as four T. pallidum polypeptide bands (30kDa, 33kDa doublet, and 35kDa). In contrast, T. pallidum absorption of NHS was found to remove treponemicidal activity against T. pallidum but not TPR; corresponding Western blots showed the complete removal of IgG antibody against all but one T. pallidum polypeptide band (47kDa) but no detectable loss in IgG antibody against the TPR polypeptides. These results suggest that antibody in NHS generated against nonpathogenic, indigenous treponemes is responsible for the T. pallidum treponemicidal activity. Furthermore, the treponemicidal activity against T. pallidum correlated with the presence of IgG antibody against T. pallidum polypeptides of 30kDa, 35kDa, and a 33kDa doublet.     

The antigenic interrelationship between the endoflagella of Treponema phagedenis biotype Reiter and Treponema pallidum Nichols strain. I. Treponemicidal activity of cross-reactive endoflagellar antibodies against T. pallidum

Treponemicidal activity against Treponema pallidum, Nichols strain, by anti-endoflagellar antibodies and the presence of antigenic interrelationships between the endoflagella of Treponema phagedenis biotype Reiter (TPR) and T. pallidum have been demonstrated. SDS-PAGE profiles of purified endoflagella from both organisms were similar, identifying five polypeptide bands for TPR (37,000, 33,000 doublet, 30,000, and 27,000 daltons) and five polypeptide bands for T. pallidum (35,000, 33,000 doublet, 30,000, and 27,000 daltons). Antiserum against TPR endoflagella identified identical bands on Western blots of TPR, T. pallidum, and the respective endoflagellar preparations. Western blots confirmed the presence of antibodies in normal human serum (NHS) against the 33,000 dalton treponemal endoflagellar proteins. The complement-dependent treponemicidal activity of NHS against T. pallidum was completely removed by absorption with purified TPR endoflagella. Furthermore, rabbit antisera against TPR endoflagella were reactive in the Treponema pallidum immobilization (TPI) test. These findings demonstrate that anti-endoflagellar antibodies are treponemicidal against T. pallidum. A possible mechanism for this activity is discussed in relation to the subsurface location of endoflagella.     

Bactericidal/permeability-increasing protein has endotoxin-neutralizing activity

Neutrophil granules contain proteins important in host defense against bacterial pathogens. Granule proteins released from activated neutrophils facilitate opsonization, phagocytosis, tissue digestion, and antimicrobial activity. Three similar, if not identical, neutrophil proteins, bactericidal/permeability-increasing protein (BPI), 57,000 m.w. cationic antimicrobial protein, and bactericidal protein have been described that specifically kill gram negative bacteria. Since LPS is a structure common to all gram-negative bacteria, we investigated whether the microbicidal protein BPI affects biologic activity of LPS in vitro. Human neutrophils can be activated both in vitro and in vivo by LPS. Upon stimulation, surface expression of CR1 and CR3 increases markedly. Using flow microfluorimetry, we analyzed surface expression of CR1 and CR3 as a measure of neutrophil stimulation in response to LPS. CR up-regulation on neutrophils was TNF independent, suggesting direct LPS stimulation of neutrophils in this system. Purified BPI completely inhibited CR up-regulation on neutrophils stimulated with both rough and smooth LPS chemotypes at 1.8 to 3.6 nM (100 to 200 ng/ml). By comparison, the polypeptide antibiotic polymyxin B completely inhibited the same dose of LPS at 0.4 nM. The inhibitory activity of BPI appeared to be specific for LPS because neutrophil stimulation by formylated peptide or TNF was unaffected. The specificity of BPI for LPS was further demonstrated by inhibition of LPS activity in the limulus amebocyte lysate assay. Therefore, the role of BPI in infection may not be limited to its microbicidal activity, but it may also regulate the neutrophil response to LPS.     

Inactivation of the vascular permeability-increasing activity of bradykinin by mycoplasmas

Mycoplasma pneumoniae, M. genitalium, M. fermentans, M. hominis, M. salivarium, M. orale, Ureaplasma urealyticum and Acholeplasma laidlawii inactivated the vascular permeability-increasing activity of bradykinin when the mixture of bradykinin and mycoplasma cells was injected after incubation at 37 degrees C for 1 h. Cell components responsible for inactivation of the activity of bradykinin were found to be arginine-specific aminopeptidase and carboxypeptidase.     

Purification of erythropoiesis-stimulating activity (ESA) from one Actinomycetes strain

An Actinomycetes strain was found to produce a protein which stimulated the growth of murine erythroid progenitors in vitro. The protein was purified to homogeneity and was named Erythropoiesis-Stimulating Activity (ESA). ESA was an acidic glycoprotein with a molecular weight around 80,000. When mouse bone marrow cells were cultured in methylcellulose medium containing physiological concentrations of erythropoietin (0.048 units/ml), addition of ESA stimulated the growth of colony forming unit-erythroid (CFU-E) up to three-fold a in dose dependent manner. ESA was not active on the other hematopoietic progenitors.     

Esterase-type of activity possessed by human plasma apolipoprotein C-II and its synthetic fragments

Human plasma apolipoproteins apoA-I, A-II, C-I, C-II and C-III (with the exception of apoE), porcine pancreatic colipase and procolipase hydrolyze 4-methylumbelliferyloleate. In all cases, liberation of 4-methylumbelliferone could be inhibited by phenylmethylsulfonylfluoride, thus suggesting the involvement of serine residues. To the best of our knowledge this is the first report on the esterase activities of these peptides. Synthetic fragments of the lipoprotein lipase activator, apoC-II, prepared according to the known sequence, also possessed this esterase-type of activity. Furthermore, the esterase-type of activities of the synthetic apoC-II fragments with different chain lengths bore a relatively good correlation to the reported abilities to these peptides to produce activation of lipoprotein lipase.We propose a model for the mechanism of activation of lipoprotein lipase by apolipoprotein C-II. ApoC-II would enhance the apparent catalytic rate constant of lipoprotein lipase by functioning as a specific acyl-enzyme hydrolase. A similar catalytic mechanism is suggested for other protein co-factors of hydrolytic enzymes.     

Evidence for the presence of lipopolysaccharide in Treponema phagedenis (biotype Reiterii) but not in Treponema pallidum (Nichols)

Abstract Immunoblotting profiles of whole or protease-K-digested organisms with homologous antisera demonstrated the presence of a characteristic ladder pattern of smooth LPS in Treponema phagedenis . Periodic acid silver staining of SDS-PAGE gels confirmed these findings. However, when heterologous or homologous serum was reacted with Treponema pallidum , no such pattern or cross-reactions were observed. The significance of apparent absence of LPS in T. pallidum is discussed.