Phenotypic consequences of LYS4 gene disruption in Candida albicans

Abstract

A BLAST search of the Candida Genome Database with the Saccharomyces cerevisiae LYS4 sequence known to encode homoaconitase (HA) revealed ORFs 19.3846 and 19.11327. Both alleles of the LYS4 gene were sequentially disrupted in Candida albicans BWP17 cells using PCR-based methodology. The null lys4Δ mutant exhibited lysine auxotrophy in minimal medium but was able to grow in the presence of L-Lys and α-aminoadipate, an intermediate of the α-aminoadipate pathway, at millimolar concentrations. The presence of D-Lys and pipecolic acid did not trigger lys4Δ growth. The C. albicans lys4Δ mutant cells demonstrated diminished germination ability. However, their virulence in vivo in a murine model of disseminated neonatal candidiasis appeared identical to that of the wild-type strain. Moreover, there was no statistically significant difference in fungal burden of infected tissues between the strains.

The lysine biosynthetic enzyme Lys4 influences iron metabolism, mitochondrial function and virulence in Cryptococcus neoformans

“…Therefore, we believe that in addition to sensitivity to the host body temperature, mitochondrial dysfunction also contributes to the attenuation of the virulence in the lys4 mutant. Lys4 has also been characterized in C. albicans but does not appear to contribute to virulence [37]. Overall, we conclude that LYS4 is not only required for lysine biosynthesis but is also necessary for the proper mitochondrial function and for the full virulence.…”

Candida albicans Cannot Acquire Sufficient Ethanolamine from the Host To Support Virulence in the Absence of De Novo Phosphatidylethanolamine Synthesis

“…For instance, an auxotroph for inositol (ino1ΔΔ), a metabolite used to synthesize the phospholipid phosphatidylinositol, is not compromised for virulence (27). In addition, auxotrophs for the amino acids lysine, histidine, leucine, and arginine are fully virulent (28,29). In addition, the related fungal pathogen Candida glabrata is a natural niacin auxotroph (30) and C. albicans is a biotin auxotroph (31,32), yet they are both virulent.…”

Consequences of lysine auxotrophy for Candida albicans adherence and biofilm formation

“…On the other hand, lysine auxotrophy results in retardation of growth and development of biofilm formation in the early stage of infection on mouse fibroblasts. It should be noted that L-Lys concentration in DMEM supplemented with 10% FBS (over 1 mM) is higher than the critical level estimated in previous studies (Kur et al, 2010;Gabriel et al, 2014), necessary for unaltered growth of C. albicans lysΔ21/lysΔ22 and lysΔ4 (~0.12 mM). Therefore, it seems likely that the observed retardation of infection development is not a consequence of general growth impairment.…”

“…In our previous works we have described some phenotypic consequences of C. albicans LYS21 and LYS22 (encoding two isoforms of homocitrate synthase) or LYS4 (encoding homoaconitase) genes disruption (Kur et al, 2010;Gabriel et al, 2014). In this study we report what are the consequences of Candida albicans lysine auxotrophy for adhesion to host tissues and plastic surfaces and for the fungi biofilm-forming ability.…”

“…The wild type SC5314 cells (Gillum et al, 1984) were maintained on minimal agar plates containing 6.7 g of Yeast Nitrogen Base w/o amino acids, 2 g of glucose, and 1.5% of agar (YNB). C. albicans lysine auxotrophic strains lysΔ21/ lysΔ22 (Kur et al, 2010) and lysΔ4 (Gabriel et al, 2014) were maintained on YNB supplemented with L-Lys (60 µg ml -1 ). Candida strains used for RHOE infection were routinely grown in the YPD medium (10 g of yeast extract, 20 g of peptone and 20 g glucose per liter) at 30°C.…”