TY - JOUR
T1 - 5-fluorocytosine resistance is associated with hypermutation and alterations in capsule biosynthesis in Cryptococcus
AU - Billmyre, R. Blake
AU - Applen Clancey, Shelly
AU - Li, Lucy X.
AU - Doering, Tamara L.
AU - Heitman, Joseph
N1 - Funding Information:
This study was supported by NIH/NIAID R37 MERIT award AI39115-21, NIH/NIAID R01 AI50113-15, NIH/NIAID R01 AI112595-04, and NIH/NIAID P01 AI104533-05 to J. H.; NIH/NIAID R21 AI109623 to T.L.D.; and NIH/NIAID F30 AI120339 to L.X.L. This study utilized a Cryptococcus gene deletion collection deposited at the Fungal Genetics Stock Center and made freely available ahead of publication by the Madhani laboratory and funded by NIH R01 AI100272.
Publisher Copyright:
© 2020, The Author(s).
PY - 2020/12/1
Y1 - 2020/12/1
N2 - Patients infected with the fungal pathogen Cryptococcus are most effectively treated with a combination of 5-fluorocytosine (5FC) and amphotericin B. 5FC acts as a prodrug, which is converted into toxic 5-fluorouracil (5FU) upon uptake into fungal cells. However, the pathogen frequently develops resistance through unclear mechanisms. Here we show that resistance to 5FC in Cryptococcus deuterogattii is acquired more frequently in isolates with defects in DNA mismatch repair that confer an elevated mutation rate. We use whole genome sequencing of 16 independent isolates to identify mutations associated with 5FC resistance in vitro. We find mutations in known resistance genes (FUR1 and FCY2) and in a gene UXS1, previously shown to encode an enzyme that converts UDP-glucuronic acid to UDP-xylose for capsule biosynthesis, but not known to play a role in 5FC metabolism. Mutations in UXS1 lead to accumulation of UDP-glucuronic acid and alterations in nucleotide metabolism, which appear to suppress toxicity of both 5FC and its toxic derivative 5FU.
AB - Patients infected with the fungal pathogen Cryptococcus are most effectively treated with a combination of 5-fluorocytosine (5FC) and amphotericin B. 5FC acts as a prodrug, which is converted into toxic 5-fluorouracil (5FU) upon uptake into fungal cells. However, the pathogen frequently develops resistance through unclear mechanisms. Here we show that resistance to 5FC in Cryptococcus deuterogattii is acquired more frequently in isolates with defects in DNA mismatch repair that confer an elevated mutation rate. We use whole genome sequencing of 16 independent isolates to identify mutations associated with 5FC resistance in vitro. We find mutations in known resistance genes (FUR1 and FCY2) and in a gene UXS1, previously shown to encode an enzyme that converts UDP-glucuronic acid to UDP-xylose for capsule biosynthesis, but not known to play a role in 5FC metabolism. Mutations in UXS1 lead to accumulation of UDP-glucuronic acid and alterations in nucleotide metabolism, which appear to suppress toxicity of both 5FC and its toxic derivative 5FU.
UR - http://www.scopus.com/inward/record.url?scp=85077530437&partnerID=8YFLogxK
U2 - 10.1038/s41467-019-13890-z
DO - 10.1038/s41467-019-13890-z
M3 - Article
C2 - 31913284
AN - SCOPUS:85077530437
SN - 2041-1723
VL - 11
JO - Nature communications
JF - Nature communications
IS - 1
M1 - 127
ER -