Two functionally distinctive phosphopantetheinyl transferases from amoeba Dictyostelium discoideum

The life cycle of Dictyostelium discoideum is proposed to be regulated by expression of small metabolites. Genome sequencing studies have revealed a remarkable array of genes homologous to polyketide synthases (PKSs) that are known to synthesize secondary metabolites in bacteria and fungi. A crucial step in functional activation of PKSs involves their post-translational modification catalyzed by phosphopantetheinyl transferases (PPTases). PPTases have been recently characterized from several bacteria; however, their relevance in complex life cycle of protozoa remains largely unexplored. Here we have identified and characterized two phosphopantetheinyl transferases from D. discoideum that exhibit distinct functional specificity. DiAcpS specifically modifies a stand-alone acyl carrier protein (ACP) that possesses a mitochondrial import signal. DiSfp in contrast is specific to Type I multifunctional PKS/fatty acid synthase proteins and cannot modify the stand-alone ACP. The mRNA of two PPTases can be detected during the vegetative as well as starvation-induced developmental pathway and the disruption of either of these genes results in non-viable amoebae. Our studies show that both PPTases play an important role in Dictyostelium biology and provide insight into the importance of PPTases in lower eukaryotes

Erythema nodosum with oral and genital ulcers: A case of behçet's disease

Behçet's disease (BD) is a chronic, relapsing, multisystemic disorder characterized by mucocutaneous, ocular, vascular, and central nervous system manifestations. The clinical spectrum includes oral and genital ulcerations, uveitis, and vascular, neurological, articular, renal, and gastrointestinal manifestations. The etiopathogenesis of the disease remains unknown although genetic predisposition, environmental factors, and immunological abnormalities have been implicated. It usually affects young adults. The case of a 22-year-old female who presented with fever, recurrent oral ulcers, genital ulcers, arthralgia, and erythema nodosum is presented here. A diagnosis of BD based on clinical criteria was made. The patient was treated with colchicine 1 mg/day which had beneficial effects on the reduction in size and recurrence of mucocutaneous ulcers

Kupyaphores are counter regulatory zinc homeostatic metallophores required for Mycobacterium tuberculosis colonization

Abstract Tuberculosis (TB) patients suffer from progressive and debilitating loss of muscle mass and function, referred to as cachexia. Though a multifactorial condition, cachexia in cancer is promoted by systemic zinc redistribution and accumulation in muscles. Clinical studies with TB patients indeed show zinc dyshomeostasis. We therefore set out to understand mechanisms by which Mycobacterium tuberculosis (Mtb) govern zinc metallostasis at the host-pathogen interface. Here, we report a novel zinc metallophore from Mtb that restores zinc metabolic imbalance. These diisonitrile lipopeptides, named kupyaphores are transiently induced early-on during macrophage infection and also in infected mice lungs. Kupyaphores protects bacteria from host-mediated nutritional deprivation and intoxication. Kupyaphore Mtb mutant strain cannot mobilize zinc and shows reduced fitness in mice. Further, we characterize Mtb encoded isonitrile hydratase that could mediate intracellular zinc release through covalent modification of kupyaphores. Our studies could provide a molecular link between TB-induced altered zinc homeostasis and associated cachexia.</jats:p

Dual Role of Endogenous Serotonin in 2,4,6-Trinitrobenzene Sulfonic Acid-Induced Colitis

Background and Aims: Changes in gut serotonin (5-HT) content have been described in Inflammatory Bowel Disease (IBD) and in different experimental models of colitis: the critical role of this monoamine in the pathogenesis of chronic gastrointestinal inflammation is gradually emerging. Aim of the present study was to evaluate the contribution of endogenous 5-HT through the activation of its specific receptor subtypes to the local and systemic inflammatory responses in an experimental model of IBD. Materials and Methods: Colitis was induced by intrarectal 2,4,6-TriNitroBenzene Sulfonic acid in mice subacutely treated with selective antagonists of 5-HT(1A) (WAY100135), 5-HT(2A) (Ketanserin), 5-HT(3) (Ondansetron), 5-HT(4) (GR125487), 5-HT(7) (SB269970) receptors and with 5-HT(1A) agonist 8-Hydroxy-2-(di-n-propylamino)tetralin. Results: Blockade of 5-HT(1A) receptors worsened TNBS-induced local and systemic neutrophil recruitment while 5-HT(1A) agonist delayed and mitigated the severity of colitis, counteracting the increase in colonic 5-HT content. On the contrary, blockade of 5-HT(2A) receptors improved global health conditions, reduced colonic morphological alterations, down-regulated neutrophil recruitment, inflammatory cytokines levels and colonic apoptosis. Antagonism of 5-HT(3), 5-HT(4), and 5-HT(7) receptor sites did not remarkably affect the progression and outcome of the pathology or only slightly improved it. Conclusion: The prevailing deleterious contribution given by endogenous 5-HT to inflammation in TNBS-induced colitis is seemingly mediated by 5-HT(2A) and, to a lesser extent, by 5-HT(4) receptors and coexists with the weak beneficial effect elicited by 5-HT(1A) stimulation. These findings suggest how only a selective interference with 5-HT pro-inflammatory actions may represent an additional potential therapeutic option for intestinal inflammatory disorders

Kupyaphores are zinc homeostatic metallophores required for colonization of <i>Mycobacterium tuberculosis</i>

Significance Mycobacterium tuberculosis ( Mtb ) is the etiological agent of human tuberculosis (TB). Mtb can persist inside host macrophages by successfully adapting to intracellular conditions. Acquisition of balanced amounts of essential micronutrients is one such important process. Our studies have identified a metallophore produced on demand to restore Mtb zinc metabolic imbalance. These diacyl-diisonitrile lipopeptides, named kupyaphores, are specifically induced during infection and move in and out of cells to protect bacteria from host-mediated nutritional deprivation and intoxication. Furthermore, we identify an Mtb isonitrile hydratase homolog , expressed in low-zinc conditions, which probably facilitates zinc release from kupyaphores. Identification of this zinc acquisition strategy could provide opportunities in future to understand systemic zinc dysbiosis and associated manifestations in TB patients. </jats:p