The cyclic structure of microcin J25, a 21-residue peptide antibiotic from Escherichia coli.
Microcin J25 (MccJ25) is the single representative of the immunity group J of the microcin group of peptide antibiotics produced by Enterobacteriaceae. It induces bacterial filamentation in susceptible cells in a non-SOS-dependent pathway [R. A. Salomon and R. Farias (1992) J. Bacteriol. 174, 7428-7435]. MccJ25 was purified to homogeneity from the growth medium of a microcin-overproducing Escherichia coli strain by reverse-phase HPLC. Based on amino acid composition and absolute configuration determination, liquid secondary ion and electrospray mass spectrometry, extensive two-dimensional NMR, enzymatic and chemical degradations studies, the structure of MccJ25 was elucidated as a 21-residue peptide, cyclo(-Val1-Gly-Ile-Gly-Thr- Pro-Ile-Ser-Phe-Tyr-Gly-Gly-Gly-Ala-Gly-His-Val-Pro-Glu-Tyr-Phe21- ). Although MccJ25 showed high resistance to most of endoproteases, linearization by thermolysin occurred from cleavage at the Phe21-Val1 bond and led to a single peptide, MccJ25-L. While MccJ25 exhibited remarkable antibiotic activity towards Salmonella newport and several E. coli strains (minimal inhibitory concentrations ranging between 0.01 and 0.2 microgram.mL-1), the thermolysin-linearized microcin showed a dramatic decrease of the activity, indicating that the cyclic structure is essential for the MccJ25 biological properties. As MccJ25 is ribosomally synthesized as a larger peptide precursor endowed with an N-terminal extremity, the present study shows that removal of this extension and head-tail cyclization of the resulting propeptide are the only post-translational modifications involved in the maturation of MccJ25, that appears as the first cyclic microcin.
Blond
A
A
Laboratoire de Chimie des Substances Naturelles, CNRS URA 401, Muséum National d'Histoire Naturelle, Paris, France.
Péduzzi
J
J
Goulard
C
C
Chiuchiolo
M J
MJ
Barthélémy
M
M
Prigent
Y
Y
Salomón
R A
RA
Farías
R N
RN
Moreno
F
F
Rebuffat
S
S
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D001430:Bacteriocins / Q000737:chemistry* / Q000494:pharmacology; D010450:Endopeptidases / Q000378:metabolism; D004926:Escherichia coli / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000737:chemistry* / Q000494:pharmacology; D012475:Salmonella / Q000187:drug effects; D016415:Sequence Alignment; D013820:Thermolysin / Q000378:metabolism
D000596:Amino Acids; D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D010456:Peptides, Cyclic; C020411:microcin; D010450:Endopeptidases; D013820:Thermolysin