Potassium uptake systems of Candida krusei

Abstract

Candida krusei is a pathogenic yeast species that is phylogenetically outside both of the well‐studied yeast groups, whole genome duplication and CUG. Like all other yeast species, it needs to accumulate high amounts of potassium cations, which are needed for proliferation and many other cell functions. A search in the sequenced genomes of nine C. krusei strains revealed the existence of two highly conserved genes encoding putative potassium uptake systems. Both of them belong to the TRK family, whose members have been found in all the sequenced genomes of species from the Saccharomycetales subclade. Analysis and comparison of the two C. krusei Trk sequences revealed all the typical features of yeast Trk proteins but also an unusual extension of the CkTrk2 hydrophilic N‐terminus. The expression of both putative CkTRK genes in Saccharomyces cerevisiae lacking its own potassium importers showed that only CkTrk1 is able to complement the absence of S. cerevisiae's own transporters and provide cells with a sufficient amount of potassium. Interestingly, a portion of the CkTrk1 molecules were localized to the vacuolar membrane. The presence of CkTrk2 had no evident phenotype, due to the fact that this protein was not correctly targeted to the S. cerevisiae plasma membrane. Thus, CkTrk2 is the first studied yeast Trk protein to date that was not properly recognized and targeted to the plasma membrane upon heterologous expression in S. cerevisiae.

The Hrk1 kinase is a determinant of acetic acid tolerance in yeast by modulating H+ and K+ homeostasis

“…A concentration of acetic acid of 60 mM for growth in agar plates was used to ensure a level of acetic acid-induced inhibition equivalent to that used in liquid media cultivations. While the potassium concentration in YPD was sufficient to sustain the growth of BYT12 and BYT12 hrk1 Δ strains, their growth was compromised in YNB medium (containing approximately 15 mM potassium [ 61 ]; Figure 4A ). Notably, the deletion of HRK1 in BYT12 did not result in any significant alteration in terms of growth enhancement or inhibition, irrespective of whether YPD or YNB media were used.…”

Minority potassium-uptake system Trk2 has a crucial role in yeast survival of glucose-induced cell death

“…Yeast Trk transporters share to a great extent a similar structure. Their membrane part contains four highly conserved so-called MPM domains [7], and they mainly differ in the length and sequence of their hydrophilic parts [8]. The structures of S. cerevisiae Trk1 and Trk2 differ mainly in the length of their first intracellular loop, which is 647 amino-acid residues long in Trk1, and only 331 amino acids in Trk2.…”

Nanopartículas lipídicas sólidas contendo óleo essencial de Melaleuca alternifolia Cheel como plataforma inovadora no tratamento da candidíase orofaríngea

“…A Candida krusei é um micro-organismo diploide que participa da fermentação de várias frutas e produtos lácteos, além de ser um patógeno oportunista, representando uma das cinco espécies mais patogênicas de Candida spp., com capacidade de causar infecções fatais (ELICHAROVA et al, 2019). Por ter características mais hidrofóbicas, adere-se fortemente aos catéteres e implantes e não forma hifas verdadeiras (CHEN et al, 2019).…”

“…Possui resistência intrínseca ao fluconazol, o que gera preocupações epidemiológicas e terapêuticas (CHEN et al, 2019;ELICHAROVA et al, 2019;FORASTIEIRO et al, 2015;KURAOKA et al, 2018;MULTANI, SUBRAMANIAN e LIU, 2019;PORTE et al, 2012), além de reduzida suscetibilidade à anfotericina B (ELICHAROVA et al, 2019). As equinocandinas demonstram ser as substâncias mais ativas contra essa espécie (FORASTIERO et al, 2015;PFALLER et al, 2008).…”