# Diverse modes of chromosome terminal deletion in spontaneous canavanine-resistant Schizosaccharomyces pombe mutants

## TL;DR

This study explores how chromosome deletions in fission yeast lead to canavanine resistance and reveals different mechanisms behind these deletions.

## Contribution

The paper identifies three distinct mechanisms of chromosome terminal deletion in canavanine-resistant fission yeast mutants.

## Key findings

- Three mutants, including can2-1, had terminal deletions of the left arm of chromosome II.
- Deletions occurred via homology-driven translocation, homology-independent fusion, and de novo telomere addition.
- These deletions caused loss of amino acid transporter genes, contributing to canavanine resistance.

## Abstract

Canavanine resistance has been used to analyze mutation rates in the fission yeast
Schizosaccharomyces pombe
. However, the genetic basis of canavanine resistance in this organism remains incompletely understood. Here, we performed whole genome sequencing on five spontaneously arising canavanine-resistant
S. pombe
mutants, including the
can2-1
mutant isolated in the 1970s. This analysis revealed that three mutants, including
can2-1
, experienced terminal deletions of the left arm of chromosome II, leading to the loss of multiple amino acid transporter genes. Interestingly, these three mutants underwent chromosome terminal deletion through distinct mechanisms, including homology-driven translocation, homology-independent chromosome fusion, and de novo telomere addition. Our findings shed new light on the genetic basis of canavanine resistance and mechanisms underlying chromosome terminal deletions in fission yeast.