Abstract
Saccharomyces cerevisiae
can change its mating type as often as every
generation by a highly choreographed, site-specific recombination event that
replaces one
MAT
allele with different DNA sequences encoding the
opposite allele. The study of this process has yielded important insights into
the control of cell lineage, the silencing of gene expression, and the
formation of heterochromatin, as well as the molecular events of double-strand
break-induced recombination. In addition,
MAT
switching provides a
remarkable example of a small locus control region-the Recombination
Enhancer-that controls recombination along an entire chromosome arm.