Genome Defense Mechanisms inNeurospora and Associated Specialized Proteins

Neurospora crassa, the filamentous fungus possesses widest array of genome defense mechanisms known to any eukaryotic organism, including a process called repeat-induced point mutation (RIP). RIP is a genome defense mechanism that hypermutates repetitive DNA sequences; analogous to genomic imprinting in mammals. As an impact of RIP, Neurospora possesses many fewer genes in multigene families than expected. A DNA methyltransferase homologue, RID was shown to be essential for RIP. Recently, a variant catalytic subunit of translesion DNA polymerase zeta (Pol  ) has been found to be essential for dominant RIP suppressor phenotype. Meiotic silencing and quelling are two other genome defense mechanisms in Neurospora, and proteins required for these two processes have been identified through genetic screens.