# The genome of the polyextremophilic yeast, Naganishia friedmannii, reveals adaptations involved in stress response pathways, carbohydrate metabolism expansion, and a limited DNA repair repertoire

## TL;DR

The genome of a yeast found in extreme high-altitude environments reveals how it adapts to survive in harsh conditions.

## Contribution

The study provides the first genome sequence of Naganishia friedmannii and identifies unique adaptations to extreme environments.

## Key findings

- The genome contains stress-related proteins and expanded carbohydrate metabolism genes for survival on wind-blown organic matter.
- The yeast has a reduced DNA repair and cell-cycle checkpoint system, possibly allowing faster reproduction in extreme conditions.
- Comparative analysis highlights unique genomic features underlying its polyextremophilic lifestyle.

## Abstract

Here we report the draft genome sequence of Naganishia friedmannii (formerly Cryptococcus friedmannii) isolate, a Basidiomycota yeast commonly found in some of the most extreme environments of the Earth's cryosphere. We isolated N. friedmannii strain Llullensis from soils at 6000 m above sea level on Volcán Llullaillaco, Argentina. The genome was 22.2 Mb with 6251 identified protein coding genes. Proteins known to be associated with thermal, osmotic, and radiation stress were identified in the genome. Comparative analysis with seven other Naganishia genomes revealed unique features underlying its polyextremophilic lifestyle. Naganishia friedmannii showed an expansion of genes involved in breaking down plant-derived carbohydrates, supporting the hypothesis that it survives at high elevations by metabolizing wind-deposited organic matter. Surprisingly, many genes involved in cell-cycle checkpoints and DNA repair were missing, as in several other Naganishia species. This extensive loss may be adaptive in extreme environments prone to abiotic stress, where a high mutation rate could generate advantageous traits, and reduced cell-cycle control may allow for faster reproduction that would be advantageous for rapid growth during brief periods of soil wetting following rare snow events.

The draft genome of Naganishia friedmannii strain Llullensis, a basidiomycete yeast isolated from 6000 m high soils on Volcán Llullaillaco, Argentina, reveals adaptations to extreme environments, including stress-related proteins, carbohydrate metabolism genes for survival on wind-blown organic matter, and a surprising loss of DNA repair and cell-cycle checkpoint genes, possibly favoring rapid adaptation and growth in harsh conditions.