Crystal M. Darby
Cornell University
Mycobacterium tuberculosisBiochemistryHomeostasisBiologyMicrobiology
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Publications 12
#1Julie V. Early (Infectious Disease Research Institute)H-Index: 5
#2Juliane Ollinger (Infectious Disease Research Institute)H-Index: 9
Last. Tanya Parish (Infectious Disease Research Institute)H-Index: 39
view all 13 authors...
To find new inhibitors of Mycobacterium tuberculosis that have novel mechanisms of action, we miniaturized a high throughput screen to identify compounds that disrupt pH homeostasis. We adapted and validated a 384-well format assay to determine intrabacterial pH using a ratiometric green fluorescent protein. We screened 89000 small molecules under nonreplicating conditions and confirmed 556 hits that reduced intrabacterial pH (below pH 6.5). We selected five compounds that disrupt intrabacterial...
4 CitationsSource
#1Nan Zhao (Cornell University)H-Index: 4
#2Mingna Sun (THU: Tsinghua University)H-Index: 8
Last. Carl Nathan (Cornell University)H-Index: 123
view all 9 authors...
Mycobacterial tuberculosis (Mtb) is able to preserve its intrabacterial pH (pHIB) near neutrality in the acidic phagosomes of immunologically activated macrophages and to cause lethal pathology in immunocompetent mice. In contrast, when its ability to maintain pHIB homeostasis is genetically compromised, Mtb dies in acidic phagosomes and is attenuated in the mouse. Compounds that phenocopy the genetic disruption of Mtb’s pHIB homeostasis could serve as starting points for drug development in the...
4 CitationsSource
#1Nan ZhaoH-Index: 4
#2Crystal M. DarbyH-Index: 6
Last. Carl NathanH-Index: 123
view all 18 authors...
Mycobacterium tuberculosis (Mtb) maintains its intrabacterial pH (pHIB) near neutrality in the acidic environment of phagosomes within activated macrophages. A previously reported genetic screen revealed that Mtb loses this ability when the mycobacterial acid resistance protease (marP) gene is disrupted. In the present study, a high throughput screen (HTS) of compounds against the protease domain of MarP identified benzoxazinones as inhibitors of MarP. A potent benzoxazinone, BO43 (6-chloro-2-(2...
15 CitationsSource
#1Crystal M. DarbyH-Index: 6
Last. Carl NathanH-Index: 123
view all 13 authors...
1 CitationsSource
#1Crystal M. Darby (Cornell University)H-Index: 6
#2Helgi I. Ingólfsson (Cornell University)H-Index: 22
Last. Carl Nathan (Cornell University)H-Index: 123
view all 13 authors...
Bacterial pathogens like Mycobacterium tuberculosis (Mtb) encounter acidic microenvironments in the host and must maintain their acid-base homeostasis to survive. A genetic screen identified two Mtb strains that cannot control intrabacterial pH (pHIB) in an acidic environment; infection with either strain led to severe attenuation in mice. To search for additional proteins that Mtb requires to survive at low pH, we introduced a whole-cell screen for compounds that disrupt pHIB, along with counte...
33 CitationsSource
Some bacterial infections can be cured with a single dose of an antibiotic, and most others can be cured with administration of one drug over several days or weeks. In contrast, routine treatment of drug-sensitive tuberculosis (TB) takes 2 mo of therapy with four drugs and an additional 4 mo with two drugs to reduce the 2-y relapse rate below 5%. The difficulty of completing prolonged treatment is a major reason for emergence of drug resistance. When the infecting strain is resistant to isoniazi...
Existing drugs are slow to eradicate Mycobacterium tuberculosis (Mtb) in patients and have failed to control tuberculosis globally. One reason may be that host conditions impair Mtb’s replication, reducing its sensitivity to most antiinfectives. We devised a high-throughput screen for compounds that kill Mtb when its replication has been halted by reactive nitrogen intermediates (RNIs), acid, hypoxia, and a fatty acid carbon source. At concentrations routinely achieved in human blood, oxyphenbut...
64 CitationsSource
Nitazoxanide (Alinia), a nitro-thiazolyl antiparasitic drug, kills diverse microorganisms by unknown mechanisms. Here we identified two actions of nitazoxanide against Mycobacterium tuberculosis (Mtb): disruption of Mtb’s membrane potential and pH homeostasis. Both actions were shared by a structurally related antimycobacterial compound, niclosamide. Reactive nitrogen intermediates were reported to synergize with nitazoxanide and its deacetylated derivative tizoxanide in killing Mtb. Herein, how...
60 CitationsSource
#1Crystal M. Darby (Cornell University)H-Index: 6
#2Aditya Venugopal (Cornell University)H-Index: 7
Last. Carl Nathan (Cornell University)H-Index: 123
view all 4 authors...
Summary The gene Rv2136c is annotated to encode the Mycobacterium tuberculosis ( Mtb ) homolog of Escherichia coli ’s undecaprenyl pyrophosphate phosphatase. In previous work, a genetic screen of 10,100 Mtb transposon mutants identified Rv2136c as being involved in acid resistance in Mtb . The Rv2136c :Tn strain was also sensitive to sodium dodecyl sulfate, lipophilic antibiotics, elevated temperature and reactive oxygen and nitrogen intermediates and was attenuated for growth and persistence in...
6 CitationsSource