The microcin J25 beta-hairpin region is important for antibiotic uptake but not for RNA polymerase and respiration inhibition

BELLOMIO A; VINCENT PA; DE ARCURI BF; SALOMON RA; MORERO RD; FARIAS RN

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS

Academic Press

Lugar: United States; Año: 2004 vol. 325 p. 1454 - 1458

0006-291X

The antibiotic microcin J25 (MccJ25) was cleaved by hydrolysis with thermolysin giving a two-chain peptide (MccJ25-Th19) of 10 and 9 amino acid residues. MccJ25-Th19 with deep modifications in beta-hairpin region had no effect on Escherichia coli growth, but still inhibited RNA polymerase in vitro and oxygen consumption in Salmonella strains. MccJ25-Th19 showed antibiotic activity on E. coli transformed with plasmids containing either fhuA or sbmA genes, which code for proteins involved in MccJ25 transport. These results suggest that an intact beta-hairpin region is crucial for MccJ25 import but not for inhibition of E. coli RNA polymerase or oxygen consumption in Salmonella strains.