The subunit S1 is important for pertussis toxin secretion

• Published in: The Journal of biological chemistry Vol. 265; no. 29; pp. 17759 - 17763
• Main Authors: Pizza, M, Bugnoli, M, Manetti, R, Covacci, A, Rappuoli, R
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 15-10-1990; American Society for Biochemistry and Molecular Biology
• Subjects: Base Sequence; Biological and medical sciences; Blotting, Western; Bordetella pertussis - genetics; Bordetella pertussis - metabolism; Cell physiology; Electrophoresis, Polyacrylamide Gel; Fundamental and applied biological sciences. Psychology; Macromolecular Substances; Molecular and cellular biology; Molecular Sequence Data; Mutagenesis, Site-Directed; mutants; Mutation; Oligonucleotide Probes; pertussis; Pertussis Toxin; Protein Sorting Signals - genetics; Secretion. Exocytosis; Virulence Factors, Bordetella - biosynthesis; Virulence Factors, Bordetella - genetics; Virulence Factors, Bordetella - isolation & purification; Toxin; Secretion; Bacteria; Biosynthesis; Bordetella pertussis; Mutation; Subunit; Conformation
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)38228-0

Pertussis toxin is a protein containing five noncovalently linked subunits which are assembled into the monomer A (containing the subunit S1) and the oligomer B (containing subunits S2, S3, S4, and S5 in a 1:1:2:1 ratio). Each of the five subunits is synthesized as a precursor containing a secretory leader peptide and is secreted into the periplasm of Bordetella pertussis where the five subunits are assembled into the oligomeric structure and then released into the culture medium. In the absence of subunit S3 the remaining subunits are not secreted into the medium, thus suggesting that the assembled structure is necessary for the release of the toxin into the supernatant. In this study we describe four B. pertussis mutants which secrete into the medium low amounts of the B oligomer of pertussis toxin. These mutants have single or multiple changes in the gene encoding the S1 subunit and synthesize S1 proteins with altered conformation which are not assembled into the holotoxin and are apparently degraded in the periplasm. These data indicate that while the B oligomer alone has the structural information necessary for the extracellular export of pertussis toxin, the S1 subunit is required for its efficient release into the medium.