Intrachromosomal tandem duplication and repeat expansion during attempts to inactivate the subtelomeric essential gene GSH1 in Leishmania.

ABSTRACT: Gamma-glutamylcysteine synthetase encoded by GSH1 is the rate-limiting enzyme in the biosynthesis of glutathione and trypanothione in Leishmania. Attempts to generate GSH1 null mutants by gene disruption failed in Leishmania infantum. Removal of even a single allele invariably led to the generation of an extra copy of GSH1, maintaining two intact wild-type alleles. In the second and even third round of inactivation, the markers integrated at the homologous locus but always preserved two intact copies of GSH1. We probed into the mechanism of GSH1 duplication. GSH1 is subtelomeric on chromosome 18 and Southern blot analysis indicated that a 10-kb fragment flanked by 466-bp direct repeated sequences was duplicated in tandem on the same chromosomal allele each time GSH1 was targeted. Polymeras

SUBMITTER: Mukherjee A 

PROVIDER: S-EPMC3177219 | biostudies-literature | 2011 Sep

REPOSITORIES: biostudies-literature