title: Molecular characterization of the Enterococcus faecalis cytolysin activator.
abstract: The gene encoding component A (cylA), the activator protein of the Enterococcus faecalis cytolysin, has been localized on pAD1, and the nucleotide sequence was determined. cylA consists of a 1,236-bp open reading frame encoding a 412-amino-acid polypeptide. A search of the National Biomedical Research Foundation data base revealed significant homology between the inferred amino acid sequence of component A and subtilisin BPN'. Component A activation of the cytolysin precursor (component L) was observed to be inhibited by the serine protease inhibitor diisopropylfluorophosphate. Mature component A exhibits a molecular weight of approximately 30,000 and an isoelectric point of 4.5. Differences between the size of the primary translation product (45,625 daltons) and the mature enzyme suggest that, as for subtilisin, component A is secreted as a proenzyme. These results provide the basis for a model of component A activation of component L and a role for component A in protecting the cytolysin-producing cell from lysis.
authors.affiliation: Department of Microbiology and Immunology, University of Oklahoma College of Medicine, Oklahoma City 73190.
authors.forename: R A
authors.initials: RA
authors.lastname: Segarra
authors.forename: M C
authors.initials: MC
authors.lastname: Booth
authors.forename: D A
authors.initials: DA
authors.lastname: Morales
authors.forename: M M
authors.initials: MM
authors.lastname: Huycke
authors.forename: M S
authors.initials: MS
authors.lastname: Gilmore
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D013293:Enterococcus faecalis / Q000235:genetics*; D029968:Escherichia coli Proteins; D007109:Immunity; D008969:Molecular Sequence Data; D008970:Molecular Weight; D013381:Subtilisins / Q000032:analysis
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D013381:Subtilisins