Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2017 Dec 21;24(12):1437-1444.e3.
doi: 10.1016/j.chembiol.2017.08.024. Epub 2017 Oct 12.

Synergy and Target Promiscuity Drive Structural Divergence in Bacterial Alkylquinolone Biosynthesis

Yihan Wu  1 , Mohammad R Seyedsayamdost  2
Affiliations

Synergy and Target Promiscuity Drive Structural Divergence in Bacterial Alkylquinolone Biosynthesis

Yihan Wu et al. Cell Chem Biol. .

Abstract

Microbial natural products are genetically encoded by dedicated biosynthetic gene clusters (BGCs). A given BGC usually produces a family of related compounds that share a core but contain variable substituents. Though common, the reasons underlying this divergent biosynthesis are in general unknown. Herein, we have addressed this issue using the hydroxyalkylquinoline (HAQ) family of natural products synthesized by Burkholderia thailandensis. Investigations into the detailed functions of two analogs show that they act synergistically in inhibiting bacterial growth. One analog is a nanomolar inhibitor of pyrimidine biosynthesis and at the same time disrupts the proton motive force. A second analog inhibits the cytochrome bc1 complex as well as pyrimidine biogenesis. These results provide a functional rationale for the divergent nature of HAQs. They imply that synergy and target promiscuity are driving forces for the evolution of tailoring enzymes that diversify the products of the HAQ biosynthetic pathway.

Keywords: Burkholderia thailandensis; antibiotics; mode of action; natural products; synergy.

PubMed Disclaimer

Figures

Figure 1
Figure 1
HMNQ and HQNO act synergistically. (A) Structures of HMNQ, HQNO, a generic fluoroquinolone antibiotic, and P. aeruginosa-derived PQS. (B) Checkerboard analysis measuring the OD600 nm of B. subtilis in the presence of various concentrations of HMNQ or HQNO. A similar result was obtained with E. coli (see also Fig. S2). The data represent averages of two independent replicates. (C) Bar chart representation of the data in panel (B) to emphasize the synergy observed. Bacterial growth, as determined by OD600 nm, is shown as a function of treatment with HQNO alone, HMNQ alone, or HMNQ and HQNO. The average of three biological replicates is shown. Error bars represent standard deviation (SD). One, two, and three stars represent p-values of <0.05, <0.01, and <0.001, respectively. (D) Isobologram analysis of the data in panel (B). The additive isobole is shown. The measured isobole clearly falls in the positive synergy region of the plot (below the dotted line).
Figure 2
Figure 2
Modes of action of HMNQ and HQNO determined by bacterial cytological profiling. (A) Typical cell cytology of E. coli visualized with three fluorophores 2 h after treatment with the indicated drug. The chosen antibiotics represent a number of known modes of antibiotic action. Note that HMNQ- and HQNO-treated cells reveal different cytological profiles. White scale bar, 2 m; red scale bar, 4 m. (B) Principal component analysis of the features in panel (A) clusters the antibiotics by mode of action. The relative contribution of each principal component is indicated by the color key. HMNQ clusters most closely with monensin and CCCP.
Figure 3
Figure 3
Effect of HMNQ and HQNO on the primary metabolome of E. coli. (A) Shown is the fold-change in the levels of 93 primary metabolites as a function of HMNQ or HQNO treatment, with respect to a no-treatment control, determined by HR-HPLC-MS. Three independent biological replicates for both drug-treated and untreated cells were used. The metabolites are sorted by fold-change. The color-coding is as follows: pyrimidine biosynthetic intermediates, red; NMPs, green; canonical amino acids, purple; NTPs, blue. (B) Biosynthetic pathway for pyrimidine nucleotides. HMNQ and HQNO inhibit DHODH, which results in accumulation of DHO and N-carbamoyl-L-aspartate (carbamoyl-Asp).
Figure 4
Figure 4
HMNQ and HQNO efficiently inhibit E. coli DHODH by competing for the quinone binding site. Lineweaver-Burke analysis for the inhibition of E. coli DHODH by HMNQ (A) or HQNO (B). Both drugs are competitive with the ubiquinone surrogate DCIP, but not with substrate DHO (see also Fig. S3). Data represent the average of two replicates; error bars are within the size of the circles.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Cao H, Krishnan G, Goumnerov B, Tsongalis J, Tompkins R, Rahme LG. A quorum sensing-associated virulence gene of Pseudomonas aeruginosa encodes a LysR-like transcription regulator with a unique self-regulatory mechanism. Proc Natl Acad Sci U S A. 2001;98:14613–14618. - PMC - PubMed
    1. Challis GL, Hopwood DA. Synergy and contingency as driving forces for the evolution of multiple secondary metabolite production by Streptomyces species. Proc Natl Acad Sci U S A. 2003;100:14555–14561. - PMC - PubMed
    1. Collier DN, Anderson L, McKnight SL, Noah TL, Knowles M, Boucher R, Schwab U, Gilligan P, Pesci EC. A bacterial cell to cell signal in the lungs of cystic fibrosis patients. FEMS Microbiol Lett. 2002;215:41–46. - PubMed
    1. Davies J. Are antibiotics naturally antibiotics? J Ind Microbiol Biotechnol. 2006;33:496–499. - PubMed
    1. Dekker KA, Inagaki T, Gootz TD, Huang LH, Kojima Y, Kohlbrenner WE, Matsunaga Y, McGuirk PR, Nomura E, Sakakibara T, et al. New quinolone compounds from Pseudonocardia sp with selective and potent anti-Helicobacter pylori activity: taxonomy of producing strain, fermentation, isolation, structural elucidation and biological activities. J Antibiot (Tokyo) 1998;51:145–152. - PubMed

Publication types

MeSH terms

LinkOut - more resources