THE RAD6 DNA-REPAIR PATHWAY IN SACCHAROMYCES-CEREVISIAE - WHAT DOES IT DO, AND HOW DOES IT DO IT

The RAD6 pathway of budding yeast, Saccharomyces cerevisiae, is responsible for a substantial fraction of this organism's resistance to DNA damage, and also for induced mutagenesis. The pathway appears to incorporate two different recovery processes, both regulated by RAD6. The error-prone recovery process accounts for only a small amount of RAD6-dependent resistance, but probably all induced mutagenesis. The underlying mechanism for error-prone recovery is very likely to be translesion synthesis. The error-free recovery process accounts for most of RAD6-dependent resistance, but its mechanism is less clear; it may entail error-free bypass by template switching and/or DNA gap filling by recombination. RAD6 regulates these activities by ubiquitinating target proteins, but the identities of these target proteins, and the roles they play in error-free and error-prone recovery, have not yet been established.