TYROSINE 9 IS THE KEY AMINOACID IN MICROCIN J25 SUPEROXIDE OVERPRODUCTION

CHALON MIRIAM; BELLOMIO AUGUSTO; SOLBIATI JOSE; MORERO ROBERTO; FARIAS RICARDO; VINCENT PAULA

FEMS MICROBIOLOGY LETTERS

Año: 2009 p. 90 - 96

0378-1097

Escherichia coli microcin J25 (MccJ25) is a lasso-peptide antibiotic comprising 21 L-amino acid residues (G1-G-A-G-H5-V-P-E-Y-F10-V-G-I-G-T15-P-I-S-F-Y20-G). MccJ25 has two independent substrates: RNA-polymerase and the membrane respiratory chain. The latter is mediated by oxygen consumption inhibition together with an increase of superoxide production. In the present paper, the antibiotic MccJ25 was engineered by substituting Tyr9 or Tyr20 with phenylalanine. Both mutants were well transported into the cells and remained active on RNA-polymerase. Only the Y9F mutant lost the ability to overproduce superoxide and inhibit oxygen consumption. The last results confirm that the Tyr9, and not Tyr20, is involved in the MccJ25 action on the respiratory chain target