From peptide precursors to oxazole and thiazole-containing peptide antibiotics: microcin B17 synthase.
Esherichia coli microcin B17 is a posttranslationally modified peptide that inhibits bacterial DNA gyrase. It contains four oxazole and four thiazole rings and is representative of a broad class of pharmaceutically important natural products with five-membered heterocycles derived from peptide precursors. An in vitro assay was developed to detect heterocycle formation, and an enzyme complex, microcin B17 synthase, was purified and found to contain three proteins, McbB, McbC, and McbD, that convert 14 residues into the eight mono- and bisheterocyclic moieties in vitro that confer antibiotic activity on mature microcin B17. These enzymatic reactions alter the peptide backbone connectivity. The propeptide region of premicrocin is the major recognition determinant for binding and downstream heterocycle formation by microcin B17 synthase. A general pathway for the enzymatic biosynthesis of these heterocycles is formulated.
Li
Y M
YM
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
Milne
J C
JC
Madison
L L
LL
Kolter
R
R
Walsh
C T
CT
D000255:Adenosine Triphosphate / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000737:chemistry / Q000494:pharmacology; D001426:Bacterial Proteins; D001430:Bacteriocins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D009876:Operon; D010080:Oxazoles / Q000032:analysis; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D011498:Protein Precursors / Q000096:biosynthesis / Q000235:genetics; D011499:Protein Processing, Post-Translational; D013379:Substrate Specificity; D013844:Thiazoles / Q000032:analysis; D059005:Topoisomerase II Inhibitors
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001430:Bacteriocins; D004791:Enzyme Inhibitors; D009097:Multienzyme Complexes; D010080:Oxazoles; D011498:Protein Precursors; D013844:Thiazoles; D059005:Topoisomerase II Inhibitors; C102057:microcin B17 synthase; C020411:microcin; D000255:Adenosine Triphosphate; D010100:Oxygen