Mechanistic studies on gliotoxin biosynthesis and self-protection in Aspergillus fumigatus, both of which require the gliotoxin oxidoreductase GliT, have revealed a rich landscape of highly novel biochemistries, yet key aspects of this complex molecular architecture remain obscure. Here we show that an A. fumigatus ⌬gliA strain is completely deficient in gliotoxin secretion but still retains the ability to efflux bisdethiobis(methylthio)gliotoxin (BmGT). This correlates with a significant increase in sensitivity to exogenous gliotoxin because gliotoxin trapped inside the cell leads to (i) activation of the gli cluster, as disabling gli cluster activation, via gliZ deletion, attenuates the sensitivity of an A. fumigatus ⌬gliT strain to gliotoxin, thus implicating cluster activation as a factor in gliotoxin sensitivity, and (ii) increased methylation activity due to excess substrate (dithiol gliotoxin) for the gliotoxin bis-thiomethyltransferase GtmA. Intracellular dithiol gliotoxin is oxidized by GliT and subsequently effluxed by GliA. In the absence of GliA, gliotoxin persists in the cell and is converted to BmGT, with levels significantly higher than those in the wild type. Similarly, in the ⌬gliT strain, gliotoxin oxidation is impeded, and methylation occurs unchecked, leading to significant S-adenosylmethionine (SAM) depletion and S-adenosylhomocysteine (SAH) overproduction. This in turn significantly contributes to the observed hypersensitivity of gliT-deficient A. fumigatus to gliotoxin. Our observations reveal a key role for GliT in preventing dysregulation of the methyl/methionine cycle to control intracellular SAM and SAH homeostasis during gliotoxin biosynthesis and exposure. Moreover, we reveal attenuated GliT abundance in the A. fumigatus ⌬gliK strain, but not the ⌬gliG strain, following exposure to gliotoxin, correlating with relative sensitivities. Overall, we illuminate new systems interactions that have evolved in gliotoxin-producing, compared to gliotoxin-naive, fungi to facilitate their cellular presence. Biosynthesis, self-protection mechanisms, and functionality of gliotoxin and related epidithiodiketopiperazine (ETP) molecular species, such as chaetocin and acetylaranotin, are attracting ever-increasing attention as a consequence of findings from highthroughput genome sequencing projects, application of gene deletion technologies, and mass spectrometric analytical methodologies (1-5). Indeed, existing paradigms of gliotoxin (Fig. 1) as a toxin and the perspective of the disulfide bridge-containing (oxidized) form as the final, or only, product are undergoing significant reconsideration (6-11).Self-protection against disulfide-containing metabolites appears to be essential in both fungi and bacteria. It has been demonstrated that the gliotoxin oxidoreductase GliT (12), encoded within the gli cluster, protects Aspergillus fumigatus against exogenous gliotoxin and is essential for gliotoxin biosynthesis (12, 13). A similar mechanism for self-protection against holomycin in Streptomyces clavulige...

Abstract. In this letter, we report the first use of oblique incidence diffuse reflectance spectrometry to conduct in-vivo measurements of optical properties of three different types of pigmented skin lesions, including melanoma, dysplastic, and common nevi. Both absorption and reduced scattering coefficient spectra were estimated from the spatially resolved diffuse reflectance within the wavelength range of 455-765 nm for 144 pigmented skin lesions including 16 melanomas. The absorption and reduced scattering spectra were found to change with the malignancy of the skin lesions, which were generally higher for the malignant cases than the benign ones. Based on the measurement results, the physiological origin leading to the change of the absorption and scattering properties is also discussed. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.3536509] Keywords: absorption coefficient; reduced scattering coefficient; diffuse reflectance; and melanoma.Paper 10556LR received Oct. 12, 2010; revised manuscript received Dec. 16, 2010; accepted for publication Dec. 16, 2010; published online Feb. 17, 2011. Melanoma is the most malignant type of skin cancer (the most common form of human cancers) and also the leading cause of death from skin diseases.1 Early detection and treatment of melanoma can significantly improve patient outcomes. Unfortunately, melanoma is difficult to diagnose by its appearance as it can closely resemble some other pigmented skin lesions, such as common nevi, dysplastic nevi, or seborrheic keratoses. As a result, an invasive biopsy procedure is generally required for accurate diagnosis. Recent studies suggest that the optical properties (e.g., absorption and scattering) of various skin lesions (pigmented or nonpigmented) would change with their different development stages, 2-5 which could be utilized to de- velop new noninvasive approaches for skin cancer detection. However, the optical properties of melanoma and other pigmented skin lesions have not been well studied or compared up to this date. In this letter, we report the first experimental study of the in-vivo optical absorption and scattering properties of 144 pigmented skin lesions, including 16 melanomas, 98 dysplastic nevi, and 30 common nevi. By using the oblique incidence diffuse reflectance spectroscopy (OIDRS), the spatiospectral diffuse reflectance (within the visible spectrum) of the skin lesions were measured in vivo. The optical absorption and scattering spectra of the skin lesions were then estimated from the measured diffuse reflectance data. Both the absorption and scattering spectra of different types of skin lesions are compared and their pathological implication is also discussed. The data acquisition was conducted at The University of Texas M.D. Anderson Cancer Center (Houston, TX). The diffuse reflectance spectra were collected from 144 pigmented skin lesions and adjacent healthy skin (for referencing). After the measurement was completed, the skin lesion was biopsied and submitted ...

Aurora kinases are cell cycle regulated serine/threonine kinases that have been linked to cancer. Compound 1 was identified as a potent Aurora inhibitor but lacked oral bioavailability. Optimization of 1 led to the discovery of a series of fluoroamine and deuterated analogues, exemplified by compound 25, with an improved pharmacokinetic profile. We found that blocking oxidative metabolism at the benzylic position and decreasing the basicity of the amine are important to obtaining compounds with good biological profiles and oral bioavailability.

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a b s t r a c t a r t i c l e i n f oGliotoxin (GT) is a redox-active metabolite, produced by Aspergillus fumigatus, which inhibits the growth of other fungi. Here we demonstrate how Aspergillus niger responds to GT exposure. Quantitative proteomics revealed that GT dysregulated the abundance of 378 proteins including those involved in methionine metabolism and induced de novo abundance of two S-adenosylmethionine (SAM)-dependent methyltransferases. Increased abundance of enzymes S-adenosylhomocysteinase (p = 0.0018) required for homocysteine generation from S-adenosylhomocysteine (SAH), and spermidine synthase (p = 0.0068), involved in the recycling of Met, was observed. Analysis of Met-related metabolites revealed significant increases in the levels of Met and adenosine, in correlation with proteomic data. Methyltransferase MT-II is responsible for bisthiobis(methylthio)gliotoxin (BmGT) formation, deletion of MT-II abolished BmGT formation and led to increased GT sensitivity in A. niger. Proteomic analysis also revealed that GT exposure also significantly (p b 0.05) increased hydrolytic enzyme abundance, including glycoside hydrolases (n = 22) and peptidases (n = 16). We reveal that in an attempt to protect against the detrimental affects of GT, methyltransferase-mediated GT thiomethylation alters cellular pathways involving Met and SAM, with consequential dysregulation of hydrolytic enzyme abundance in A. niger. Thus, it provides new opportunities to exploit the response of GT-naïve fungi to GT.

The imidazo-[1,2-a]-pyrazine (1) is a dual inhibitor of Aurora kinases A and B with modest cell potency (IC 50 = 250 nM) and low solubility (5 μM). Lead optimization guided by the binding mode led to the acyclic amino alcohol 12k (SCH 1473759), which is a picomolar inhibitor of Aurora kinases (TdF K d Aur A = 0.02 nM and Aur B = 0.03 nM) with improved cell potency (phos-HH3 inhibition IC 50 = 25 nM) and intrinsic aqueous solubility (11.4 mM). It also demonstrated efficacy and target engagement in human tumor xenograft mouse models.

The ever-increasing bacterial resistance to clinical antibiotics is making many drugs ineffective and creating significant treatment gaps. This can be only circumvented by the discovery of antibiotics with new mechanisms of action. We report here the identification of a new tetramic acid, ascosetin, from an Ascomycete using the Staphylococcus aureus fitness test screening method. The structure was elucidated by spectroscopic methods including 2D NMR and HRMS. Relative stereochemistry was determined by ROESY and absolute configuration was deduced by comparative CD spectroscopy. Ascosetin inhibited bacterial growth with 2-16 μg ml(-1) MIC values against Gram-positive strains including methicillin-resistant S. aureus. It also inhibited the growth of Haemophilus influenzae with a MIC value of 8 μg ml(-1). It inhibited DNA, RNA, protein and lipid synthesis with similar IC50 values, suggesting a lack of specificity; however, it produced neither bacterial membrane nor red blood cell lysis. It showed selectivity for bacterial growth inhibition compared with fungal but not mammalian cells. The isolation, structure and biological activity of ascosetin have been detailed here.

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