Fig. 3
Analysis of the kng gene cluster and the activity of Kangs A, V1, and V2. a Comparison of the rifamycin (rif) and Kang (kng) gene clusters. Lines connecting the two clusters indicate genes that are predicted to be functionally equivalent. For simplicity, only genes lacking a counterpart in the rif cluster are labeled in the kng cluster. Colored boxes surrounding these genes correspond to the substructures they are predicted to encode (shown in panel C). b Structures of Kangs A, V1 and V2. c Summary of the proposed biosynthesis of Kang V2. The structure of Kang V2 is colored as follows: red, PK core; blue, Emal modification; green, AHBA-derived substructure; black, tailoring modifications. Colored bubbles highlighting the key structural features of Kang V2 correspond with the genes in (A) that are predicted to encode for these features. The PKS module 8 dehydratase (dh) domain, which is predicted to be inactive, is shown in lower case letters to differentiate it from the remaining, active domains. d In vivo activity profiles of the Kangs against RifR Sau. The structure of Rif is shown along with the three most commonly mutated RNAP residues in RifR Mtb clinical isolates3, 29. The dashed line and arcs indicate an H-bond and nonpolar contacts, respectively. e. In vitro transcription assay with radiolabeled nucleotides showing the activity of Rif and the Kangs at the concentrations indicated against Msm wild-type and RifR βS447L RNAP. F, full-length transcript; A, abortive transcript
