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"Goodwin, Michael"
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Fumarate Reductase Activity Maintains an Energized Membrane in Anaerobic Mycobacterium tuberculosis
Oxygen depletion of Mycobacterium tuberculosis engages the DosR regulon that coordinates an overall down-regulation of metabolism while up-regulating specific genes involved in respiration and central metabolism. We have developed a chemostat model of M. tuberculosis where growth rate was a function of dissolved oxygen concentration to analyze metabolic adaptation to hypoxia. A drop in dissolved oxygen concentration from 50 mmHg to 0.42 mmHg led to a 2.3 fold decrease in intracellular ATP levels with an almost 70-fold increase in the ratio of NADH/NAD(+). This suggests that re-oxidation of this co-factor becomes limiting in the absence of a terminal electron acceptor. Upon oxygen limitation genes involved in the reverse TCA cycle were upregulated and this upregulation was associated with a significant accumulation of succinate in the extracellular milieu. We confirmed that this succinate was produced by a reversal of the TCA cycle towards the non-oxidative direction with net CO(2) incorporation by analysis of the isotopomers of secreted succinate after feeding stable isotope ((13)C) labeled precursors. This showed that the resulting succinate retained both carbons lost during oxidative operation of the TCA cycle. Metabolomic analyses of all glycolytic and TCA cycle intermediates from (13)C-glucose fed cells under aerobic and anaerobic conditions showed a clear reversal of isotope labeling patterns accompanying the switch from normoxic to anoxic conditions. M. tuberculosis encodes three potential succinate-producing enzymes including a canonical fumarate reductase which was highly upregulated under hypoxia. Knockout of frd, however, failed to reduce succinate accumulation and gene expression studies revealed a compensatory upregulation of two homologous enzymes. These major realignments of central metabolism are consistent with a model of oxygen-induced stasis in which an energized membrane is maintained by coupling the reductive branch of the TCA cycle to succinate secretion. This fermentative process may offer unique targets for the treatment of latent tuberculosis.
Journal Article
Combining native and ‘omics’ mass spectrometry to identify endogenous ligands bound to membrane proteins
Ligands bound to protein assemblies provide critical information for function, yet are often difficult to capture and define. Here we develop a top-down method, ‘nativeomics’, unifying ‘omics’ (lipidomics, proteomics, metabolomics) analysis with native mass spectrometry to identify ligands bound to membrane protein assemblies. By maintaining the link between proteins and ligands, we define the lipidome/metabolome in contact with membrane porins and a mitochondrial translocator to discover potential regulators of protein function.
‘Nativeomics’ enables identification of ligands bound to membrane proteins through detection of intact protein–ligand assemblies followed by dissociation and identification of individual ligands within the same mass spectrometry experiment.
Journal Article
Metronidazole prevents reactivation of latent Mycobacterium tuberculosis infection in macaques
Targeting Mycobacterium tuberculosis bacilli in low-oxygen microenvironments, such as caseous granulomas, has been hypothesized to have the potential to shorten therapy for active tuberculosis (TB) and prevent reactivation of latent infection. We previously reported that upon low-dose M. tuberculosis infection, equal proportions of cynomolgus macaques develop active disease or latent infection and that latently infected animals reactivated upon neutralization of TNF. Using this model we now show that chemoprophylaxis of latently infected cynomolgus macaques with 6 mo of isoniazid (INH) effectively prevented anti-TNF antibody-induced reactivation. Similarly, 2-mo treatment of latent animals with a combination of INH and rifampicin (RIF) was highly effective at preventing reactivation disease in this model. Metronidazole (MTZ), which has activity only against anaerobic, nonreplicating bacteria, was as effective as either of these treatments in preventing reactivation of latent infection. Because hypoxic lesions also occur during active TB, we further showed that addition of MTZ to INH/RIF effectively treated animals with active TB within 2 mo. Healing lesions were associated with distinct changes in cellular pathology, with a shift toward increasingly fibrotic and calcified lesions. Our data in the nonhuman primate model of active and latent TB supports targeting bacteria in hypoxic environments for preventing reactivation of latent infection and possibly shortening the duration of therapy in active TB.
Journal Article
Socioeconomic disparities in health-related quality of life among colorectal cancer survivors
PurposeImprovements in colorectal cancer (CRC) prevention, early detection, and treatment have resulted in substantial gains in survival. However, the health-related quality of life (HRQoL) of CRC survivors often depends on access to supportive care, which differs by survivors’ socioeconomic characteristics. The purpose of this study was to investigate the relationship between socioeconomic characteristics and HRQoL in a diverse group of CRC survivors.MethodsWe conducted a population-based, cross-sectional study to examine the association between socioeconomic factors (household income, health literacy, and insurance status) and HRQoL domains of pain interference, fatigue, physical function, sleep disturbance, anxiety, and depression. PROMIS® Short Forms v.2.0 were used to assess domains of HRQoL. Linear regression modeling was used to estimate the coefficient representing the average HRQoL domain score and its 95% confidence interval (CI).ResultsThree hundred one CRC survivors participated in the survey. Low-income (≤ $30,000) CRC survivors had, on average, a 4.70-point (95% CI 1.10–8.28) higher pain interference score, a 7.02-point (95% CI 3.27–10.77) higher fatigue score, a 5.13-point (95% CI − 8.56 to − 1.71) lower physical function score, and a 4.44-point (95% 1.40–7.49) higher depression score than CRC survivors with an income ≥ $ 70,000. Survivors with Medicaid insurance reported significantly greater pain interference and worse physical function than privately insured survivors. Survivors with low health literacy reported significantly greater pain interference compared with survivors with high health literacy.ConclusionsSubstantial socioeconomic disparities in HRQoL were observed in this diverse population of CRC survivors.Implications for Cancer SurvivorsDesigning supportive care interventions to improve HRQoL among low-income and Medicaid-insured CRC survivors is critical for eliminating disparities in CRC outcomes.
Journal Article
Environmental fungi target thiol homeostasis to compete with Mycobacterium tuberculosis
Mycobacterial species in nature are found in abundance in sphagnum peat bogs where they compete for nutrients with a variety of microorganisms including fungi. We screened a collection of fungi isolated from sphagnum bogs by co-culture with Mycobacterium tuberculosis ( Mtb ) to look for inducible expression of antitubercular agents and identified 5 fungi that produced cidal antitubercular agents upon exposure to live Mtb . Whole genome sequencing of these fungi followed by fungal RNAseq after Mtb exposure allowed us to identify biosynthetic gene clusters induced by co-culture. Three of these fungi induced expression of patulin, one induced citrinin expression and one induced the production of nidulalin A. The biosynthetic gene clusters for patulin and citrinin have been previously described but the genes involved in nidulalin A production have not been described before. All 3 of these potent electrophiles react with thiols and treatment of Mtb cells with these agents followed by Mtb RNAseq showed that these natural products all induce profound thiol stress suggesting a rapid depletion of mycothiol. The induction of thiol-reactive mycotoxins through 3 different systems in response to exposure to Mtb suggests that fungi have identified this as a highly vulnerable target in a similar microenvironment to that of the caseous human lesion.
Journal Article
A highly conserved host lipase deacylates oxidized phospholipids and ameliorates acute lung injury in mice
Oxidized phospholipids have diverse biological activities, many of which can be pathological, yet how they are inactivated in vivo is not fully understood. Here, we present evidence that a highly conserved host lipase, acyloxyacyl hydrolase (AOAH), can play a significant role in reducing the pro-inflammatory activities of two prominent products of phospholipid oxidation, 1-palmitoyl-2-glutaryl-sn-glycero-3-phosphocholine and 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine. AOAH removed the sn-2 and sn-1 acyl chains from both lipids and reduced their ability to induce macrophage inflammasome activation and cell death in vitro and acute lung injury in mice. In addition to transforming Gram-negative bacterial lipopolysaccharide from stimulus to inhibitor, its most studied activity, AOAH can inactivate these important danger-associated molecular pattern molecules and reduce tissue inflammation and injury.
Journal Article
In Situ SIMS Analysis and Reactions of Surfaces Prepared by Soft Landing of Mass-Selected Cations and Anions Using an Ion Trap Mass Spectrometer
Mass-selected polyatomic cations and anions, produced by electrosonic spray ionization (ESSI), were deposited onto polycrystalline Au or fluorinated self-assembled monolayer (FSAM) surfaces by soft landing (SL), using a rectilinear ion trap (RIT) mass spectrometer. Protonated and deprotonated molecules, as well as intact cations and anions generated from such molecules as peptides, inorganic catalysts, and fluorescent dyes, were soft-landed onto the surfaces. Analysis of the modified surfaces was performed in situ by Cs
+ secondary ion mass spectrometry (SIMS) using the same RIT mass analyzer to characterize the sputtered ions as that used to mass select the primary ions for SL. Soft-landing times as short as 30 s provided surfaces that yielded good quality SIMS spectra. Chemical reactions of the surfaces modified by SL were generated in an attached reaction chamber into which the surface was transferred under vacuum. For example, a surface on which protonated triethanolamine had been soft landed was silylated using vapor-phase chlorotrimethylsilane before being returned still under vacuum to the preparation chamber where SIMS analysis revealed the silyloxy functionalization. SL and vapor-phase reactions are complementary methods of surface modification and in situ surface analysis by SIMS is a simple way to characterize the products produced by either technique.
A soft-landing instrument that allows in situ SIMS analysis of modified surfaces as well as in situ chemical reactions is described and characterized.
Journal Article