Change of a single amino acid in the leader peptide of a staphylococcal beta-lactamase prevents the appearance of the enzyme in the medium.
A plasmid encoded beta-lactamase gene from Staphylococcus aureus (strain 3804) was cloned and sequenced. The nucleotide sequence is very similar to those obtained for other such beta-lactamase genes. The beta-lactamase has an N-terminal region characteristic of an exported protein and assay of activity shows that the enzyme is found extracellularly in S. aureus. A residue in the N-terminal region near to the postulated cleavage site was changed by site-directed mutagenesis from a serine into a proline. Comparison of beta-lactamase activity outside the cell in strains containing the cloned wild-type and mutagenised genes shows that this single amino acid completely prevents the appearance of the enzyme in the medium.
Microbiology Unit, Department of Biochemistry, Oxford, U.K.
A K
AK
East
S P
SP
Curnock
K G
KG
Dyke
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D021382:Protein Sorting Signals / Q000235:genetics* / Q000378:metabolism; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D013211:Staphylococcus aureus / Q000201:enzymology / Q000235:genetics*; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
D004269:DNA, Bacterial; D021382:Protein Sorting Signals; D001618:beta-Lactamases