Author:
Barrett J F,Barrett T A,Curtiss R
Abstract
The presence of proteases in culture supernatant fluids and on the cell surface of Streptococcus sobrinus and the aggregation of multicomponent enzyme complexes make the isolation and characterization of cell surface proteins difficult. We report a simple purification procedure for dextranase and the cloning of the dextranase structural gene. S. sobrinus culture supernatant fluids were precipitated with 70% ammonium sulfate, and the precipitate was dialyzed against sodium acetate buffer and loaded onto a hemoglobin-Sepharose 4B column connected to a blue dextran-agarose column at 4 degrees C. After being washed with low concentrations of salt, the dextranase and the dextran-binding proteins were eluted with 5 M KI and further purified by gel filtration. Two dextranases (molecular weights, 175,000 and 160,000) were purified and partially characterized. The structural gene for the dextranase of S. sobrinus 6715 strain UAB66, serotype g, was cloned into the cosmid vector, pHC79. Clones were selected for expression of dextranase activity by detection of zones of enzyme-mediated hydrolysis of a blue dextran substrate incorporated into minimal medium agar plates. Release of dextranase was achieved by induction of thermoinducible, excision-defective Escherichia coli K-12 lysogens containing recombinant cosmid molecules of S. sobrinus DNA. Recombinant cosmid molecules were repackaged simultaneously into infectious lambdoid particles. Recombinant clones expressing dextranase activity which varied in size from the high-molecular-weight protein produced by S. sobrinus (i.e., 175,000) to lower-molecular-weight forms expressed by S. sobrinus have been identified and partially characterized.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Reference67 articles.
1. Barrett J. F. T. A. Barrett and R. Curtiss III. 1986. Biochemistry and genetics of dextranase from Streptococcus sobrinus 6715 p. 205-215. In S. Hamada S. M. Michalek H. Kiyono L. Menaker and J. R. McGhee (ed.) Molecular microbiology and immunobiology of Streptococcus mutans. Elsevier Science Publishing Inc. New York.
2. Renaturation of dextranase activity from culture supernatant fluids of Streptococcus sobrinus after sodium dodecyl sulfate polyacrylamide gel electrophoresis;Barrett J. F.;Anal. Biochem.,1986
3. A rapid alkaline extraction procedure for screening recombinant plasmid DNA;Birnboim H.;Nucleic Acids Res.,1979
4. Effects of dextranase on cariogenic and acariogenic dextrans;Bowen W. H.;Brit. Dent. J.,1968
5. Substratecontaining gel electrophoresis: sensitive detection of amylolytic, nucleolytic and proteolytic enzymes;Brown T. L.;Anal. Biochem.,1982
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