Investigation of Cryptococcus neoformans magnesium transporters reveals important role of vacuolar magnesium transporter in regulating fungal virulence factors

Abstract

Cryptococcus neoformans is an important opportunistic fungal pathogen in humans. Recent studies have demonstrated that metals are critical factors for the regulation of fungal virulence in hosts. In this study, we systemically investigated the function of C. neoformans magnesium transporters in controlling the intracellular Mg balance and virulence‐associated factors. We identified three Mg transporters in C. neoformans: Mgt1, Mgt2, and Mgt3. While we could not detect a Mg2+‐related growth phenotype in mgt1 and mgt3 knockout strains, a GAL7p‐Mgt2 strain showed significant Mg‐dependent growth defects in the presence of glucose. Further analysis demonstrated that MGT2 is a homolog of MNR2 in Saccharomyces cerevisiae, which is localized to the vacuolar membrane and participates in intracellular Mg transport. Interestingly, a transcriptome analysis showed that Mgt2 influenced the expression of 19 genes, which were independent of Mg2+. We showed that melanin synthesis in C. neoformans required Mg2+ and Mgt2, and that capsule production was negatively regulated by Mg2+ and Mgt2. Repressing the expression of MGT2‐induced capsule, which resulted in an increased fungal burden in the lungs. Cumulatively, this study sets the stage for further evaluation of the important role of Mg homeostasis in the regulation of melanin and capsule in C. neoformans.

Fungal acetylome comparative analysis identifies an essential role of acetylation in human fungal pathogen virulence

“…The transcriptome analysis was performed as previously described, with modifications 37 . For the analysis of deacetylase inhibitors, C. neoformans cells were treated or not treated with 3 μM TSA and 20 mM NAM in 50 ml of YPD media at 30 °C for 6 h. For the analysis of dac2Δ and dac4Δ, overnight cell cultures of the wild-type H99, dac2Δ, and dac4Δ strains were subcultured in fresh YPD media, and the cultures were incubated at 30 °C until the cell densities reached the exponential phase (approximately 6–7 h).…”

Integrative Proteome and Acetylome Analyses of Murine Responses to Cryptococcus neoformans Infection

“…Overnight culture was then washed three times with PBS buffer and diluted in PBS. As described elsewhere, 10 5 C. neoformans cells were used for infection (Suo et al, 2018;. For fungal burden analysis, YPD agar was used.…”

“…Traditional investigations have provided valuable information to understanding the response of a C. neoformans infected host, but they focused primarily on mRNA levels, neglecting the roles of proteome and protein posttranslational modification in the host (Suo et al, 2018). Protein lysine acetylation (Kac) is a conserved posttranslational modification that links acetyl-coenzyme A metabolism, including histone and non-histone acetylation (Shakespear et al, 2011).…”

Transcriptional regulation of the virulence genes and the biofilm formation associated operons in Vibrio parahaemolyticus

“…The master quorum sensing (QS) regulators AphA and OpaR oppositely regulate the transcription of cpsQ - mfpABC and mfpABC during different stages of V. parahaemolyticus growth, leading to gradual increases in their transcription with the transition from low cell density (LCD) to high cell density (HCD) [ 2 ]. The LysR-type transcriptional regulator CalR is calcium-regulated transcription factor that also can bind to the upstream DNA regions of mfpABC to activate its transcription [ 5 , 6 ].…”

“…In addition to directly regulating mfpABC transcription, CalR was shown to be involved in directly regulating transcription of the type VI secretion system 2 (T6SS2) gene, tdh2 and T3SS1 genes as well as swarming motility [ 5 – 8 ]. In addition, transcription of calR is directly activated by the transmembrane regulator ToxR, which was first described as a transcriptional activator of cholera toxin [ 7 , 9 , 10 ].…”