TABLE 5.

Comparison of resistance-conferring point mutations in the S. coelicolor trpRS2 locus

EntryORFa or locusb introduced into B725 (indolmycin-sensitive S. coelicolor)MICc (μg/ml)Fold increase in MICd
1 S. coelicolor trpRS2 ORF0.251
2 S. coelicolor TrpRS2(L9F) ORF520
3 S. coelicolor TrpRS2(H48Q) ORF>75>300
4 S. coelicolor TrpRS2(H48N) ORF>75>300
5 S. coelicolor TrpRS2(Q13K) ORF312
6 S. coelicolor TrpRS2(L9F/Q13K) ORF832
7 S. coelicolor TrpRS2(L9F/H48Q) ORF>75>300
8 S. coelicolor trpRS2 locus0.251
9 S. coelicolor TrpRS2[C(−17)A] locus28
10 S. coelicolor TrpRS2[C(−17)A/L9F] locus520
11 S. coelicolor TrpRS2[C(−17)A/H48Q] locus>75>300
12 S. coelicolor TrpRS2[G(−13)T] locus520
13 S. coelicolor TrpRS2[G(−13)T/L9F] locus1248
14 S. coelicolor TrpRS2[G(−13)T/H48Q] locus>75>300
  • a All ORFs were introduced into strain B725 under the ermE* promoter for equalized expression in vivo (see Materials and Methods).

  • b Locus refers to the region spanning 93 nucleotides upstream and 96 nucleotides downstream of the trpRS2 ORF (see Materials and Methods).

  • c MIC is the concentration of indolmycin sufficient to inhibit the growth of each strain after 2 days on Difco nutrient agar (see Materials and Methods).

  • d Fold increase in MIC relative to that of indolmycin-sensitive S. coelicolor strain B725 (MIC = 0.25 μg/ml). Note that wild-type S. coelicolor (MIC > 150 μg/ml) is more than 600-fold more resistant to indolmycin than strain B725.