Dataset Information

Mannich base limits Candida albicans virulence by inactivating Ras-cAMP-PKA pathway.

ABSTRACT: Mannich bases and its derivatives are regarded as supreme pharmacophores in therapeutics. The study investigates the antimycotic potential of Mannich bases, 1-((1H-benzimidazol-1-yl) methyl) urea (C1) and 1-((3-hydroxynapthalen-2-yl) methyl) thiourea (C2), against Candida albicans. Biofilm and hyphal inhibitory activities of the Mannich bases were tested by crystal violet quantification, fluorescence imaging cAMP rescue, qRT PCR, and by molecular docking analysis. The compounds inhibited the biofilms of C. albicans and restrained the filamentation abilities of the pathogen. Structure-activity relationship studies revealed that the presence of urea or thiourea moiety in the tail section is essential for interacting with adenylate cyclase (AC). The Mannich bases seemed to block Ras-cAMP-PKA pathway by inhibiting second messenger activity required for hyphal induction and biofilm formation. In conclusion, the study warrants point-of-care testing of C1/C2 and provides a starting point for deriving several structurally modified Mannich bases which might plausibly replace the prevailing antimycotic drugs in future.

SUBMITTER: Rajasekharan SK

PROVIDER: S-EPMC6175908 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

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Mannich base limits Candida albicans virulence by inactivating Ras-cAMP-PKA pathway.

Rajasekharan Satish Kumar SK Kamalanathan Chakkaravarthi C Ravichandran Vinothkannan V Ray Arvind Kumar AK Satish Ann Susan AS Mohanvel Sucharitha Kannappan SK

Scientific reports 20181008 1

Mannich bases and its derivatives are regarded as supreme pharmacophores in therapeutics. The study investigates the antimycotic potential of Mannich bases, 1-((1H-benzimidazol-1-yl) methyl) urea (C1) and 1-((3-hydroxynapthalen-2-yl) methyl) thiourea (C2), against Candida albicans. Biofilm and hyphal inhibitory activities of the Mannich bases were tested by crystal violet quantification, fluorescence imaging cAMP rescue, qRT PCR, and by molecular docking analysis. The compounds inhibited the bio ...[more]

PMID: 30297833

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Project description:UnlabelledCandida albicans is the most prevalent fungal pathogen of humans, causing a variety of diseases ranging from superficial mucosal infections to deep-seated systemic invasions. Mucus, the gel that coats all wet epithelial surfaces, accommodates C. albicans as part of the normal microbiota, where C. albicans resides asymptomatically in healthy humans. Through a series of in vitro experiments combined with gene expression analysis, we show that mucin biopolymers, the main gel-forming constituents of mucus, induce a new oval-shaped morphology in C. albicans in which a range of genes related to adhesion, filamentation, and biofilm formation are downregulated. We also show that corresponding traits are suppressed, rendering C. albicans impaired in forming biofilms on a range of different synthetic surfaces and human epithelial cells. Our data suggest that mucins can manipulate C. albicans physiology, and we hypothesize that they are key environmental signals for retaining C. albicans in the host-compatible, commensal state.ImportanceThe yeast Candida albicans causes both superficial infections of the mucosa and life-threatening infections upon entering the bloodstream. However, C. albicans is not always harmful and can exist as part of the normal microbiota without causing disease. Internal body surfaces that are susceptible to infection by C. albicans are coated with mucus, which we hypothesize plays an important role in preventing infections. Here, we show that the main components of mucus, mucin glycoproteins, suppress virulence attributes of C. albicans at the levels of gene expression and the corresponding morphological traits. Specifically, mucins suppress attachment to plastic surfaces and human cells, the transition to cell-penetrating hyphae, and the formation of biofilms (drug-resistant microbial communities). Additionally, exposure to mucins induces an elongated morphology that physically resembles the mating-competent opaque state but is phenotypically distinct. We suggest that mucins are potent antivirulence molecules that have therapeutic potential for suppressing C. albicans infections.

Project description:The conserved cAMP-dependent protein kinase (PKA) holoenzyme is composed of two catalytic and two regulatory subunits. It plays critical roles in the regulation of many biological processes in eukaryotic organisms. In the human fungal pathogen Candida albicans, the PKA kinase has been extensively investigated for its importance in the regulation of morphological transitions and virulence. It has been long thought that the PKA catalytic subunit is essential for cell viability in C. albicans. Paradoxically, the single adenylyl cyclase-encoding gene, CRY1, which is required for the production of cAMP in C. albicans, is not essential for cell growth. In this study, we successfully generated a null double mutant of TPK1 and TPK2 (tpk2/tpk2 tpk1/tpk1 or t2t1), which encode two isoforms of the PKA catalytic subunit in C. albicans. We reevaluated the roles of the PKA catalytic subunit in cell growth and phenotypic transitions. Inactivation of the PKA catalytic subunit by deletion of both TPK1 and TPK2 blocked filamentation and dramatically attenuated the ability of white-to-opaque switching, but promoted sexual mating in C. albicans. Tpk2 plays a major role in these regulations, while Tpk1 generally functions as a negative regulator in morphological transitions and sexual mating. A comparative transcriptomic analysis demonstrated that the t2t1 and cyr1/cyr1 mutants exhibited similar global gene expression profiles. Compared to the WT strain, the general transcriptional activity and expression of genes involved in metabolism, translation, biosynthesis, adhesion and filamentation are significantly decreased in both the t2t1 and cyr1/cyr1 mutants. And a portion of stress-response and cell wall-related genes were upregulated in these mutants, which is consistent with their increased ability of anti-stresses. To further explore the global regulatory role of the PKA kinase, we performed quantitative phosphoproteomics analysis. Combining with bioinformatics analyses, we identified 181 potential PKA phosphorylation targets, which represent 148 unique proteins involved in a wide spectrum of biological processes. Cell wall and membrane-related proteins (e.g. Ecm3, Bni1, and Smi1) were enriched in Tpk1-specific targets, while Tpk2-specific substrates include transporters, filamentation and cytoskeleton-related proteins (e.g. Smf3, Sep7, and Mhp1). There were also many Tpk1 and Tpk2 overlapped and coordinately regulated-substrates. Our study clarifies the essentiality of the PKA catalytic subunit and shed new insights into the global regulatory features of the cAMP/PKA pathway in C. ablicans. The t2t1 null mutant generated in this study would also be a new resource for the field to study this important pathway.

Dataset Information

Mannich base limits Candida albicans virulence by inactivating Ras-cAMP-PKA pathway.

Publications

Mannich base limits Candida albicans virulence by inactivating Ras-cAMP-PKA pathway.

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