New lipopeptide homologues (AF, AF, and AF) with antifungal activities against and spp. were purified from a cell-free supernatant of RLID 12.1. The lipopeptides AF, AF, and AF were identified with the same peptide sequence Asn-Pro-Tyr-Asn-Gln-Thr-Ser with variations in the fatty acid branching type and chain length (-C, -C, and -C, respectively). Upon comparing the three homologues for MICs against 81 ( = 64) and ( = 17) clinical isolates and their cytotoxicities, we found that AF was the most promising antifungal lipopeptide, since it demonstrated 100% inhibition at geometric mean MICs of 3.31, 3.41, 3.48, and 2.83 μg/ml against ,, , and, respectively, with low hemolysis values (<6%) and 50% inhibitory concentrations (13.31 μg/ml). The additive effects among the homologues AF, AF, and AF were evaluated against three species, along with the cytotoxicity studies. Five combinations exhibited good additive interaction effects: AF/AF (at corresponding concentrations of 4 and 4 μg/ml [4/4 μg/ml]), AF/AF (4/4 μg/ml), AF/AF (2/4 μg/ml), AF/AF (4/4 μg/ml), and AF/AF (2/4 μg/ml) in planktonic cell inhibition and AF/AF (4/4 μg/ml), AF/AF (4/4 μg/ml), and AF/AF (2/4 μg/ml) in the inhibition of biofilm formation. However, combinations AF/AF and AF/AF, which showed >70% cell survival with low hemolysis (<5%), were found to be comparatively effective. We describe here the additive effects of lipopeptide homologues showing reduced cytotoxicity against mammalian cells; these combinations might serve as a potent antibiofilm-forming substitute.

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Fifty-six strains from the GRACE collection were found to be sensitive to MMS upon repression. Deletion of the HOF1 gene renders sensitivity to genotoxic stress. Hof1 is genetically linked to the Rad53 pathway and is down-regulated in a Rad53-dependent manner. The importance of Hof1 in MMS response is reduced in a Rad23 or Rad4 mutant strain.

The assimilation of inorganic sulphate and the synthesis of the sulphur-containing amino acids methionine and cysteine is mediated by a multi-branched biosynthetic pathway. We have investigated this circuitry in the fungal pathogen Candida albicans, which is phylogenetically intermediate between the filamentous fungi and Saccharomyces cerevisiae. In S. cerevisiae this pathway is regulated by a collection of five transcription factors (Met4, Cbf1, Met28 and Met31/Met32), while in the filamentous fungi the pathway is controlled by a single Met4-like factor. We found that in C. albicans the Met4 ortholog is also a core regulator of methionine biosynthesis, where it functions together with Cbf1. While C. albicans encodes this Met4 protein, a Met4 paralog designated Met28 (Orf19.7046), and a Met31 protein, deletion and activation constructs suggest that of these proteins only Met4 is actually involved in regulation of methionine biosynthesis. Both Met28 and Met31 are linked to other functions; Met28 appears essential, and Met32 appears implicated in regulation of genes of central metabolism. Therefore, while S. cerevisiae and C. albicans share Cbf1 and Met4 as central elements of the methionine biosynthesis control, the other proteins that make up the circuit in S. cerevisiae are not members of the C. albicans control network, and so the S. cerevisiae circuit likely represents a recently evolved arrangement.

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Transcription factors play key roles in cellular regulation and are critical in the control of drug resistance in the fungal pathogen Candida albicans. We found that activation of the transcription factor C4_02500C_A (Adr1) conferred significant resistance against fluconazole. In Saccharomyces cerevisiae, Adr1 is a carbon-source-responsive zinc-finger transcription factor required for transcription of the glucose-repressed gene ADH1 and of genes required for ethanol, glycerol, and fatty acid utilization. Motif scanning of promoter elements suggests that Adr1 may be rewired in fungi and governs the ergosterol synthesis pathway in C. albicans. Because previous studies have identified the zinc-cluster transcription factor Upc2 as a regulator of the ergosterol pathway in both fungi, we examined the relationship of Adr1 and Upc2 in sterol biosynthesis in C. albicans.  Phenotypic profiles of either ADR1 and UPC2 modulation in C. albicans showed differential growth in the presence of fluconazole; either adr1 or upc2 homozygous deletion results in sensitivity to the drug while their activation generates a fluconazole resistant strain. The rewiring from ergosterol synthesis to fatty acid metabolism involved all members of the Adr1 regulon except the alcohol dehydrogenase Adh1, which remains under Adr1 control in both circuits and may have been driven by the lifestyle of S. cerevisiae, which requires the ability to both tolerate and process high concentrations of ethanol.

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