Chemical structure and translation inhibition studies of the antibiotic microcin C7.
Escherichia coli microcin C7 (MccC7) is an antibiotic that inhibits protein synthesis in vivo. It is a heptapeptide containing unknown modifications at the N and C termini (García-Bustos, J. F., Pezzi, N., and Méndez, E. (1985) Antimicrob. Agents Chemoth. 27, 791-797). The chemical structure of MccC7 has been characterized by use of 1H homonuclear and heteronuclear (13C, 15N, 31P) nuclear magnetic resonance spectroscopy as well as mass spectrometry (1177 +/- 1 Da). The heptapeptide Met-Arg-Thr-Gly-Asn-Ala-Asp is substituted at the N terminus by a N-formyl group. The C-terminal substituent consists of the phosphodiester of 5'-adenylic acid and n-aminopropanol (AMPap), which is linked via the phosphorus atom to an amide group, thus forming a phosphoramide. The main chain carbonyl of the C-terminal aspartic acid residue is connected via this amide bond to the modified nucleotide unit. MccC7 and the peptide unit inhibit protein translation in vitro while a synthetic analog of the AMPap substituent is not active. Neither the peptide nor the AMPap molecule has an effect on the growth of MccC7-sensible cells. Our results strongly suggest that the peptide is responsible for MccC7 antibiotic activity while the C-terminal substituent is needed for MccC7 transport. Implications of the structure determined in this work for MccC7 synthesis and mode of action are discussed.
Guijarro
J I
JI
Laboratoire de Résonance Magnétique Nucléaire (CNRS URA 1129), Paris, France.
González-Pastor
J E
JE
Baleux
F
F
San Millán
J L
JL
Castilla
M A
MA
Rico
M
M
Moreno
F
F
Delepierre
M
M
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D001430:Bacteriocins / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology; D004926:Escherichia coli / Q000235:genetics; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D015394:Molecular Structure; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors / Q000737:chemistry / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D011500:Protein Synthesis Inhibitors; C020411:microcin