A Single Amino Acid Substitution in One of the Lipases of Aspergillus nidulans Confers Resistance to the Antimycotic Drug Undecanoic Acid

Abstract

A plausible approach to evaluate the inhibitory action of antifungals is through the investigation of the fungal resistance to these drugs. We describe here the molecular cloning and initial characterization of the A. nidulans lipA gene, where mutation (lipA1) conferred resistance to undecanoic acid, the most fungitoxic fatty acid in the C(7:0)-C(18:0) series. The lipA gene codes for a putative lipase with the sequence consensus GVSIS and WIFGGG as the catalytic signature. Comparison of the wild-type and LIP1 mutant strain nucleotide sequences showed a G --> A change in lipA1 allele, which results in a Glu(214) --> Lys substitution in LipA protein. This ionic charge change in a conserved LipA region, next to its catalytic site, may have altered the catalytic properties of this enzyme resulting in resistance to undecanoic acid.

Transcriptome-wide survey of gene expression changes and alternative splicing in Trichophyton rubrum in response to undecanoic acid

“…Although speculative, these findings suggest that an increase in the keratinase activity seems not be related to an overproduction of the secreted enzyme. It might instead be the result of posttranslational modifications, which could affect either the rate of enzymatic catalysis or the catalytic affinity of the enzyme for the substrate 9 . Also, it might correlate to the changes in metabolic events affecting the association with other proteins.…”

“…Also, it might correlate to the changes in metabolic events affecting the association with other proteins. Indeed, a previous report hinted that the mutation on the A. nidulans lipA gene ( lipA1 allele), which codes for a putative lipase, has a pleiotropic effect on the pattern of posttranslational modifications and secretion of enzymes, concomitantly with the adaptive response to UDA 9 . Moreover, the impact of posttranslational modifications on the activity of other secreted enzymes by fungi has been documented 42 – 44 .…”

“…Their presence in human skin and sweat acts as a barrier against cutaneous infections 8 . Undecanoic acid (UDA), a medium-chain fatty acid (C 11:0 ), is the most fungitoxic compound in the C 7:0 –C 18:0 series and has been used in the treatment of superficial mycoses in humans 8 , 9 . UDA inhibits vegetative growth, conidial germination, cellular respiration 10 , carbohydrate metabolism 11 , phosphate uptake 12 , and phospholipid metabolism 8 .…”

In vitro susceptibility to antimycotic drug undecanoic acid, a medium-chain fatty acid, is nutrient-dependent in the dermatophyte Trichophyton rubrum

“…The misuse of antifungal drugs exacerbates this situation by encouraging the growth of resistant strains . A plausible approach to evaluate the inhibitory action of antifungal agents is through the investigation of the fungal resistance to these drugs (Brito-Madurro et al 2008). Another option is to study the effects of the drugs on specific enzymes or under different growth conditions, and to establish whether they correlate with the pathogenicity phenotype (Brito-Madurro et al 2008).…”

Análise do Perfil Transcricional do Dermatófito Trichophyton rubrum durante a Interação com o Agente Inibidor Acriflavina

“…Eight candidate genes (Table 1) were selected based on their common use as endogenous controls in some fungal species and other organisms, i.e., 18S rRNA and actin ( T. rubrum [21,22] and Candida albicans [23,24]), gapdh and chs1 ( T . rubrum [12]), β -tubulin ( Fonsecaea monophora [25]), and top2, atpD and rpb2 ( Xanthomonas citri [17]). Specifi c primer pairs for the reference genes were designed using the PrimerExpress v.3 software (Applied Biosystems), and their specifi city was confi rmed by BLAST searches.…”