title: A novel functional assay for fungal histidine kinases group III reveals the role of HAMP domains for fungicide sensitivity.
abstract: Signal transduction systems comprising histidine kinases are suggested as new molecular targets of antibiotics. The important human fungal pathogen Candida albicans possesses three histidine kinases, one of which is the type III histidine kinase CaNik1, which activates the MAP kinase Hog1. We established a screening system for inhibitors of this class of histidine kinases by functional expression of the CaNIK1 gene in S. cerevisiae. This transformant was susceptible to fungicides to which the wild type strain was resistant, such as fludioxonil and ambruticin. Growth inhibition correlated with phosphorylation of Hog1 and was dependent on an intact Hog1 pathway. At the N-terminus the histidine kinase CaNik1 has four amino acid repeats of 92 amino acids each and one truncated repeat of 72 amino acids. Within these repeats we identified 9 HAMP domains with a paired structure. We constructed mutants in which one or two pairs of these domains were deleted. S. cerevisiae transformants expressing the full-length CaNIK1 showed the highest sensitivity to the fungicides, any truncation reduced the susceptibility of the transformants to the fungicides. This indicates that the HAMP domains are decisive for the mode of action of the antifungal compounds.
authors.affiliation: Helmholtz Centre for Infection Research, Department of Biological Systems Analysis, Inhoffenstr.7, 38124 Braunschweig, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Buschart
authors.forename: Katja
authors.initials: K
authors.lastname: Gremmer
authors.forename: Mohammed
authors.initials: M
authors.lastname: El-Mowafy
authors.forename: Joop
authors.initials: J
authors.lastname: van den Heuvel
authors.forename: Peter P
authors.initials: PP
authors.lastname: Mueller
authors.forename: Ursula
authors.initials: U
authors.lastname: Bilitewski
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D004149:Dioxoles / Q000494:pharmacology; D025141:Drug Resistance, Fungal / Q000235:genetics*; D005656:Fungal Proteins / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics; D000071677:Histidine Kinase; D008826:Microbial Sensitivity Tests; D020928:Mitogen-Activated Protein Kinases / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011494:Protein Kinases / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics; D011714:Pyrans / Q000494:pharmacology; D011758:Pyrroles / Q000494:pharmacology; D011994:Recombinant Proteins / Q000737:chemistry / Q000187:drug effects / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017384:Sequence Deletion; D015398:Signal Transduction / Q000235:genetics; D013312:Stress, Physiological
chemical_list: D000935:Antifungal Agents; D004149:Dioxoles; D005656:Fungal Proteins; D047428:Protein Kinase Inhibitors; D011714:Pyrans; D011758:Pyrroles; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; C088589:HOG1 protein, S cerevisiae; D020928:Mitogen-Activated Protein Kinases; D000071677:Histidine Kinase; C108339:fludioxonil; C014964:ambruticin