Antimicrobial octapeptin C4 analogues active against Cryptococcus species

Resistance to antimicrobials is a growing problem in both developed and developing countries. In nations where AIDS is most prevalent, the human fungal pathogen Cryptococcus neoformans is a significant contributor to mortality, and its growing resistance to current antifungals an ever-expanding threat. We investigated octapeptin C4, from the cationic cyclic lipopeptide class of antimicrobials, as a potential new antifungal. Octapeptin C4 was a potent, selective inhibitor of this fungal pathogen with minimum inhibitory concentration of 1.56 μg/mL. Further testing of octapeptin C4 against 40 clinical isolates of C. neoformans var. grubii or neoformans showed MIC 1.56-3.13 μg/mL while 20 clinical isolates of C. neoformans var. gattii had MIC 0.78-12.5 μg/mL. In each case MIC values for octapeptin C4 were equivalent to, or better than, current antifungal drugs fluconazole and amphotericin B. The negatively charged polysaccharide capsule of C. neoformans influences the pathogens sensitivity to octapeptin C4 while degree of melanisation had little effect. Testing synthetic octapeptin C4 derivatives provided insight into the structure activity relationships, revealing that the lipophilic amino acid moieties are more important to the activity than the cationic diaminobutyric acid groups. Octapeptins have promising potential for development as anticryptococcal therapeutic agents

De quelques catéchismes créoles anciens: oublis, pertes, disparitions, réapparitions, découvertes

Il existe, dans le très vaste domaine des études postcoloniales, des territoires contigus ou semblables qui connaissent des phénomènes communs mais aux histoires très différentes, sinon radicalement opposées : tels les catéchismes - en langues romanes - fruit de la colonisation. Plus précisément, à l’histoire des catéchismes issus de la colonisation hispano-américaine, s’oppose l’histoire des catéchismes issus de la colonisation française, de l’Amérique et d’ailleurs. Ces derniers arrivent un siècle et demi environ après les espagnols et se manifestent de tout autre manière ; différents en sont l’époque, la scène et les acteurs : les destinateurs mais surtout les destinataires. Ce travail se propose de retracer l’histoire souvent aventureuse des plus anciens catéchismes des colonies ou ex-colonies françaises de la Caraïbe et de l’Océan Indien ; écrits en créole ou, parfois, en d’autres langues autochtones, ils constituent aussi des témoignages linguistiques absolument précieux. Rédigés généralement sur place, mais non toujours publiés, leur histoire est faite d’oublis, pertes, disparitions, réapparitions et découvertes. - - - In the wide field of postcolonial studies, there exist related or similar areas whose stories are nevertheless very different, if not indeed opposed. This is the case of catechisms in Romance languages (or of Romance origin), outcomes of European colonization. In particular, contradictions between the history of catechisms from Hispanic-American colonization and the catechisms produced by French colonization, in America and elsewhere. The latter appear a century and a half after the Spanish texts, and exhibit completely distinct characteristics: different periods, settings, actors, and especially recipients. I set out to recount the often adventurous history of the oldest catechisms in the French colonies, or ex-colonies, of the Caribbean and the Indian Ocean. Written in Creole or sometimes other indigenous languages, they are precious linguistic records. Compiled in the colonies, but not always published, these texts are often forgotten, lost, misplaced, resurfaced, discovered

Purine acquisition and synthesis by human fungal pathogens

While members of the Kingdom Fungi are found across many of the world's most hostile environments, only a limited number of species can thrive within the human host. The causative agents of the most common invasive fungal infections are , , and . During the infection process, these fungi must not only combat the host immune system while adapting to dramatic changes in temperature and pH, but also acquire sufficient nutrients to enable growth and dissemination in the host. One class of nutrients required by fungi, which is found in varying concentrations in their environmental niches and the human host, is the purines. These nitrogen-containing heterocycles are one of the most abundant organic molecules in nature and are required for roles as diverse as signal transduction, energy metabolism and DNA synthesis. The most common life-threatening fungal pathogens can degrade, salvage and synthesize de novo purines through a number of enzymatic steps that are conserved. While these enable them to adapt to the changing purine availability in the environment, only de novo purine biosynthesis is essential during infection and therefore an attractive antimycotic target

Rethinking the targets for antifungal development

Cryptococcus neoformans is the leading cause of fungal meningoencephalitis and one of the major causes of death in immunocompromised individuals; this AIDS-defining illness has a reported fatality rate of up to 20% in high-income countries such as Australia, and as high as 65% in developing nations(1,2). The current treatment regime recommended by the World Health Organization is induction therapy with flucytosine and amphotericin B, followed by maintenance and consolidation therapy of fluconazole(3). Development of resistance to these drugs is an ever-present threat given the pathogen undergoes microevolution while infecting the host, with evidence that this contributes to the high rate of relapse. It is therefore essential that we develop additional classes of antifungal drugs, particularly ones that are more effective than those currently available. But due to the shared eukaryotic physiology of fungi and humans, gross differences that can be exploited as drug targets such as those targeted by current antifungals are limited

Targeting Lysyl Oxidase Family Meditated Matrix Cross-Linking as an Anti-Stromal Therapy in Solid Tumours

The lysyl oxidase (LOX) family of enzymes are a major driver in the biogenesis of desmoplastic matrix at the primary tumour and secondary metastatic sites. With the increasing interest in and development of anti-stromal therapies aimed at improving clinical outcomes of cancer patients, the Lox family has emerged as a potentially powerful clinical target. This review examines how lysyl oxidase family dysregulation in solid cancers contributes to disease progression and poor patient outcomes, as well as an evaluation of the preclinical landscape of LOX family targeting therapeutics. We also discuss the suitability of the LOX family as a diagnostic and/or prognostic marker in solid tumours

A Genomic Safe Haven for Mutant Complementation in <i>Cryptococcus neoformans</i>

<div><p>Just as Koch’s postulates formed the foundation of early infectious disease study, Stanley Falkow’s molecular Koch’s postulates define best practice in determining whether a specific gene contributes to virulence of a pathogen. Fundamentally, these molecular postulates state that if a gene is involved in virulence, its removal will compromise virulence. Likewise, its reintroduction should restore virulence to the mutant. These approaches are widely employed in <i>Cryptococcus neoformans</i>, where gene deletion via biolistic transformation is a well-established technique. However, the complementation of these mutants is less straightforward. Currently, one of three approaches will be taken: the gene is reintroduced at the original locus, the gene is reintroduced into a random site in the genome, or the mutant is not complemented at all. Depending on which approach is utilized, the mutant may be complemented but other genes are potentially disrupted in the process. To counter the drawbacks of the current approaches to complementation we have created a new tool to assist in this key step in the study of a gene’s role in virulence. We have identified and characterized a small gene-free region in the <i>C</i>. <i>neoformans</i> genome dubbed the “safe haven”, and constructed a plasmid vector that targets DNA constructs to this preselected site. The plasmid vector integrates with high frequency, effectively complementing a mutant strain without disrupting adjacent genes. qRT-PCR of the flanking genes on either side of the safe haven site following integration of the targeting vector revealed no changes in their expression, and no secondary phenotypes were observed in a range of phenotypic assays including an intranasal murine infection model. Combined, these data confirm that we have successfully created a much-needed molecular resource for the <i>Cryptococcus</i> community, enabling the reliable fulfillment of the molecular Koch’s postulates.</p></div

Integration of the vector into the safe haven site does not affect expression of flanking genes.

<p>Transcript abundance of <i>CNAG_00777</i> and <i>CNAG_00778</i> relative to <i>ACT1</i> with (H99 + empty vector) and without (H99) integration of vector at the safe haven site. Values show mean, error bars show S.E.M.</p

An <i>ade2</i>Δ mutant cannot grow on YNB media lacking adenine.

<p>All complemented strains created in this study have wild-type levels of growth on YNB media and are of normal color.</p

Non-homologous ends inhibit successful homologous integration.

<p>Illustration of the polylinker sequence after being cut with each of three rare cutting restriction enzymes. The construct depiction indicates where the marker and gene as well as the two flanking regions would be located after linearization. The red sequence shows residual polylinker sequence after digestion. Percent integration indicates the proportion of antibiotic resistant colonies in which the targeting vector was correctly integrated at the safe haven site as determined by multiplex PCR after biolistic transformation.</p