-
[show abstract]
[hide abstract]
ABSTRACT: The discovery of novel small molecules that function as antibacterial agents or cellular probes of biology is hindered by our limited understanding of bacterial physiology and our ability to assign mechanism of action. We previously employed a chemical genomic strategy to identify a novel small molecule, MAC13243, as a likely inhibitor of the bacterial lipoprotein targeting chaperone, LolA. Here, we report on the degradation of MAC13243 into the active species, S-(4-chlorobenzyl)isothiourea. Analogs of this compound (e.g., A22) have previously been characterized as inhibitors of the bacterial actin-like protein, MreB. Herein, we demonstrate that the antibacterial activity of MAC13243 and the thiourea compounds are similar; these activities are suppressed or sensitized in response to increases or decreases of LolA copy number, respectively. We provide STD NMR data which confirms a physical interaction between LolA and the thiourea degradation product of MAC13243, with a Kd of ∼150μM. Taken together, we conclude that the thiourea series of compounds share a similar cellular mechanism that includes interaction with LolA in addition to the well-characterized target MreB.
Bioorganic & medicinal chemistry letters 02/2013; · 2.65 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: One of the most significant hurdles to developing new chemical probes of biological systems and new drugs to treat disease is that of understanding the mechanism of action of small molecules discovered with cell-based small-molecule screening. Here we have assembled an ordered, high-expression clone set of all of the essential genes from Escherichia coli and used it to systematically screen for suppressors of growth inhibitory compounds. Using this chemical genomic approach, we demonstrate that the targets of well-known antibiotics can be identified as high copy suppressors of chemical lethality. This approach led to the discovery of MAC13243, a molecule that belongs to a new chemical class and that has a unique mechanism and promising activity against multidrug-resistant Pseudomonas aeruginosa. We show that MAC13243 inhibits the function of the LolA protein and represents a new chemical probe of lipoprotein targeting in bacteria with promise as an antibacterial lead with Gram-negative selectivity.
Nature Chemical Biology 09/2009; 5(11):849-56. · 14.69 Impact Factor
-
Nature 04/2009; 458(7234):39-40. · 36.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Small-molecule screening campaigns of model bacteria have been conducted extensively in biotechnology and pharmaceutical companies to search for novel compounds with antibacterial activity. Recently, there has been increasing interest in running such high-throughput screens within academic settings to answer questions in biology. In this respect, whole-cell screening has the particular advantage of identifying compounds with physical and chemical properties compatible with microbial cell permeation, thereby providing probes with which to study diverse aspects of microbial cell physiology and biochemistry. The focus of this chapter is to describe a general method of running a high-throughput screen against a model bacterium to identify small molecules with growth inhibitory activity. Once the primary bioactives have been identified, the determination of their dose-response relationships with the target microbe further characterizes their growth inhibitory effect.
Methods in molecular biology (Clifton, N.J.) 02/2009; 486:13-27.
