Purification and partial characterization of neuraminidase from type III group B streptococci

Optimization and comparative characterization of neuraminidase activities from Pseudomonas aeruginosa with Klebsiella pneumoniae, Hep-2 cell, sheep kidney and rat liver lysosome

BACKGROUND AND OBJECTIVES

The properties of neuraminidase produced by P. aeruginosa strain PAO1 during growth in a defined medium (BHI) was examined and compared with some neuraminidase features of K. pneumoniae in this investigation.

MATERIALS AND METHODS

The enzyme was isolated from concentrated culture supernatants of P. aeruginosa which was used in a sensitive fluorometric assay by using 2'-(4-methylumbelliferyl) α-D-N acetylneuraminic acid as substrate.

RESULTS

Neuraminidase production in P. aeruginosa PAO1 paralleled bacterial growth in defined medium (BHI) and was maximal in the late logarithmic phase of growth but decreased during the stationary phase, probably owing to protease production or thermal instability. Highest production of P. aeruginosa PAO1 neuraminidase was in BHI culture media. The neuraminidase of P. aeruginosa PAO1 possessed an optimum temperature of activity at 56°C and the activity was maximal at pH 5. Heating the enzyme to 56°C for 45 min., in the presence of bovine serum albumin destroyed 33.1% of it's activity and addition of Ca(+2), EDTA and NANA also decreased activity markedly.

CONCLUSION

The results revealed that the highest specific activity is for p. aeruginosa PAO1.

Group B streptococcal neuraminidase is actually a hyaluronidase

The extracellular group B streptococcal enzyme described in numerous reports as a neuraminidase is really a hyaluronidase. Over the past 25 years, the enzyme was routinely assayed with bovine submaxillary mucin as the substrate and by the thiobarbituric acid procedure to measure released sialic acid. Characterization of the actual compound released by the enzyme revealed it to be an alpha,beta-unsaturated derivative of hyalobiuronic acid that was derived from hyaluronic acid contaminating the mucin preparation. Previous reports describing an association of elevated levels of extracellular neuraminidase with virulent strains of group B streptococci must be reevaluated with the recognition that the enzyme is really a hyaluronidase.

Neuraminidase production by a Pasteurella haemolytica A1 strain associated with bovine pneumonia

The properties of an extracellular neuroaminidase produced by a Pasteurella haemolytica A1 strain (isolated from a case of bovine pneumonia) during growth in a defined medium were examined in this investigation. This enzyme, isolated from concentrated culture supernatants of P. haemolytica A1, was active against N-acetylneuramin lactose, human alpha 1-acid glycoprotein, fetuin, and bovine submaxillary mucin. Neuraminidase production paralleled bacterial growth in a defined medium and was maximal in the stationary phase of growth. The enzyme was purified to homogeneity by a combination of salt fractionation, ion-exchange chromatography on DEAE-Sephacel, and gel filtration on Sephadex G-200. These procedures yielded an enzyme preparation that possessed a specific activity of 100.62 mumol of sialic acid released per min per mg of protein against human alpha 1-acid glycoprotein. The Km value for this enzyme with human alpha 1-acid glycoprotein as the substrate was 1.1 mg/ml, and the enzyme possessed a pH optimum of 6.5. The P. haemolytica A1 neuraminidase had a molecular weight of approximately 150,000 as estimated by gel filtration and approximately 170,000 when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme was stable at 4 degrees C for 3 h. At 37 degrees C for 3 h, 25% of enzymatic activity was lost. Approximately 55% of the enzyme activity was lost within 30 min at 50 degrees C, with greater than 70% of the enzyme activity being destroyed within 10 min at temperatures of > or = 65 degrees C.

Purification and immunological characterization of neuraminidase produced by Streptococcus pneumoniae

Previous workers have suggested that Streptococcus pneumoniae, the pneumococcus, produces multiple forms of the enzyme neuraminidase. By serial chromatography on DEAE-cellulose, Sephacryl S-200, Amicon Red-A gel and hydroxylapatite we have purified to electrophoretic homogeneity a pneumococcal neuraminidase with an apparent molecular weight of 86,000 (as determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis). Mouse antiserum raised against the purified material reacted with a single species with molecular weight 107,000 (107K form) in crude pneumococcal cell lysate. During the purification procedure this species was progressively degraded to the molecular weight 86,000 (86K) form whilst retaining enzyme activity. Degradation of neuraminidase was inhibited by phenylmethylsulphonylfluoride (PMSF) and ethylenediaminetetraacetic acid (EDTA). Purification of the enzyme in the presence of these protease inhibitors permitted the isolation of the 107K species substantially undegraded and greater than 98% pure. Our findings on the degradation of neuraminidase during its purification account for previous reports of multiple neuraminidase isoenzymes in Streptococcus pneumoniae.

Characterization of neuraminidases produced by various serotypes of group B streptococci

Neuraminidase produced by 11 strains of group B streptococci (GBS), from serotypes Ia, Ib, Ic, II, and III, were characterized according to molecular weight, antigenic identity, and substrate specificity. Following growth in a chemically defined medium, ammonium sulfate-concentrated culture supernatants were assayed for activity with bovine submaxillary mucin as substrate. Neuraminidase produced by GBS strain 122 (serotype III) was purified by a combination of salt fractionation, affinity chromatography with Affi-Gel Blue, ion-exchange chromatography with DEAE-cellulose, and gel filtration on Sephadex G-200. Purified neuraminidase was used to immunize rabbits, and the resultant antiserum reduced the activity of purified neuraminidase from strain 122 by 87.7%. The antiserum also reduced the activity of neuraminidases produced by the other four serotypes by between 78.3 and 90%. Molecular weight estimates of the neuraminidases produced by the various serotypes were obtained by gel filtration chromatography on Sephadex G-200. The molecular weights obtained for the neuraminidases from the representative strains of each serotype ranged from 110,000 to 180,000. In addition, all of the GBS neuraminidases examined (regardless of the producing serotype) were active only on bovine submaxillary mucin. On the basis of these results, it appears that the neuraminidases produced by different GBS serotypes are quite similar.

Neuraminidase production by a Streptococcus sanguis strain associated with subacute bacterial endocarditis

The properties of an extracellular neuraminidase produced by a Streptococcus sanguis strain (isolated from a confirmed case of subacute bacterial endocarditis) during growth in a defined medium was examined in this investigation. This enzyme, isolated from concentrated culture supernatants of S. sanguis biotype II, was active against human alpha-1 acid glycoprotein, N-acetylneuramin lactose, bovine submaxillary mucin, and fetuin. Neuraminidase production paralleled bacterial growth in defined medium and was maximal in the early stationary phase of growth but decreased dramatically, probably owing to protease production, during the late stationary phase. The enzyme was purified to near homogeneity by a combination of salt fractionation, ion-exchanged chromatography on DEAE-Sephacel, and gel filtration on Sephadex G-200. These procedures yielded an enzyme preparation that possessed a specific activity of 174.4 mumol of sialic acid released per min per mg of protein against human alpha-1 acid glycoprotein. The Km value for this enzyme with human alpha-1 acid glycoprotein as substrate was 2.5 X 10(-3) M, and the enzyme possessed a pH optimum of 6.5. The S. sanguis neuraminidase had a molecular weight of approximately 85,000 as estimated by gel filtration and approximately 90,000 when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme was stable at temperatures of 4 and 37 degrees C for 3 h, but approximately 50% of the enzymatic activity was lost within 30 min at 50 degrees C, with 100% of the enzymatic activity being destroyed within 10 min at temperatures of greater than or equal to 65 degrees C.

Isolation, chemical composition, and molecular size of extracellular type II and type Ia polysaccharides of group B streptococci

Polysaccharides carrying the type II- and type Ia-specific determinants of Lancefield group B streptococci were isolated and purified by anion-exchange chromatography and gel filtration from the supernatant culture medium after growth of strain 18RS21/67/1 (type II) and strain DS/1204/78 (type Ia), respectively. The average molecular weights of these polysaccharides were 97,000 (type II) and 94,000 (type Ia), as determined by reducing end group analyses. These molecular weights were in reasonably good agreement with molecular weights determined by gel filtration at high ionic strength on calibrated columns. The polysaccharides did not cross-react with antisera specific for the other type-specific determinants or with group B-specific antisera. Their content of galactose, glucose, glucosamine, and neuraminic acid (the last two calculated as N-acetyl derivatives) accounted for over 96% of their dry weight. The two polysaccharides differed from each other (and from type III polysaccharide) in their relative content of these monosaccharides. The molar ratios of galactose, glucose, and neuraminic acid to glucosamine were 3.3:2.3:1.35:1.0 for the type II polysaccharide and 2.0:0.8:1.4:1.0 for the type Ia polysaccharides. The results obtained indicate that these extracellular type II and Ia polysaccharides contain larger amounts of neuraminic acid than can be accounted for by previously proposed structures of their repeating units.

Purification and some properties of neuraminidase isolated from the culture medium of oral bacterium Streptococcus mitis ATCC 9811

Neuraminidase acting on the salivary bacterial agglutinating factor was isolated and purified from the culture medium of Streptococcus mitis ATCC 9811. The molecular weight and the isoelectric point of the enzyme were determined to be 42,000 and a pH of 4.6, respectively. The enzyme showed high activity against human glycoprotein substrates, especially the salivary bacterial agglutinating factor.