PCR screening reveals considerable unexploited biosynthetic potential of ansamycins and a mysterious family of AHBA-containing natural products in actinomycetes
Article first published online: 15 MAY 2013
Journal of Applied Microbiology © 2013 The Society for Applied Microbiology
Journal of Applied Microbiology
Volume 115, Issue 1, pages 77–85, July 2013
How to Cite
Wang, H.-X., Chen, Y.-Y., Ge, L., Fang, T.-T., Meng, J., Liu, Z., Fang, X.-Y., Ni, S., Lin, C., Wu, Y.-Y., Wang, M.-L., Shi, N.-N., He, H.-G., Hong, K. and Shen, Y.-M. (2013), PCR screening reveals considerable unexploited biosynthetic potential of ansamycins and a mysterious family of AHBA-containing natural products in actinomycetes. Journal of Applied Microbiology, 115: 77–85. doi: 10.1111/jam.12217
- Issue published online: 12 JUN 2013
- Article first published online: 15 MAY 2013
- Accepted manuscript online: 18 APR 2013 03:34AM EST
- Manuscript Accepted: 14 APR 2013
- Manuscript Revised: 30 MAR 2013
- Manuscript Received: 22 NOV 2012
- NSFC. Grant Numbers: 31100079, 2010TS072
- AHBA synthase;
- AHBA-containing natural products;
- PCR screening
Ansamycins are a family of macrolactams that are synthesized by type I polyketide synthase (PKS) using 3-amino-5-hydroxybenzoic acid (AHBA) as the starter unit. Most members of the family have strong antimicrobial, antifungal, anticancer and/or antiviral activities. We aimed to discover new ansamycins and/or other AHBA-containing natural products from actinobacteria.
Methods and Results
Through PCR screening of AHBA synthase gene, we identified 26 AHBA synthase gene–positive strains from 206 plant-associated actinomycetes (five positives) and 688 marine-derived actinomycetes (21 positives), representing a positive ratio of 2·4–3·1%. Twenty-five ansamycins, including eight new compounds, were isolated from six AHBA synthase gene–positive strains through TLC-guided fractionations followed by repeated column chromatography. To gain information about those potential ansamycin gene clusters whose products were unknown, seven strains with phylogenetically divergent AHBA synthase genes were subjected to fosmid library construction. Of the seven gene clusters we obtained, three show characteristics for typical ansamycin gene clusters, and other four, from Micromonospora spp., appear to lack the amide synthase gene, which is unusual for ansamycin biosynthesis. The gene composition of these four gene clusters suggests that they are involved in the biosynthesis of a new family of hybrid PK-NRP compounds containing AHBA substructure.
PCR screening of AHBA synthase is an efficient approach to discover novel ansamycins and other AHBA-containing natural products.
Significance and Impact of the Study
This work demonstrates that the AHBA-based screening method is a useful approach for discovering novel ansamycins and other AHBA-containing natural products from new microbial resources.