SAD-2 is required for meiotic silencing by unpaired DNA and perinuclear localization of SAD-1 RNA-directed RNA polymerase.
A gene unpaired during the meiotic homolog pairing stage in Neurospora generates a sequence-specific signal that silences the expression of all copies of that gene. This process is called Meiotic Silencing by Unpaired DNA (MSUD). Previously, we have shown that SAD-1, an RNA-directed RNA polymerase (RdRP), is required for MSUD. We isolated a second gene involved in this process, sad-2. Mutated Sad-2 (RIP) alleles, like those of Sad-1, are dominant and suppress MSUD. Crosses homozygous for Sad-2 are blocked at meiotic prophase. SAD-2 colocalizes with SAD-1 in the perinuclear region, where small interfering RNAs have been shown to reside in mammalian cells. A functional sad-2(+) gene is necessary for SAD-1 localization, but the converse is not true. The data suggest that SAD-2 may function to recruit SAD-1 to the perinuclear region, and that the proper localization of SAD-1 is important for its activity.
Shiu
Patrick K T
PK
Division of Biological Sciences, University of Missouri, Columbia, MO 65211, USA. shuip@missouri.edu
Zickler
Denise
D
Raju
Namboori B
NB
Ruprich-Robert
Gwenael
G
Metzenberg
Robert L
RL
D020137:Base Pair Mismatch / Q000235:genetics; D023902:Chromosome Pairing; D004271:DNA, Fungal / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D020868:Gene Silencing; D005799:Genes, Dominant; D005800:Genes, Fungal; D008540:Meiosis / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D009491:Neurospora / Q000201:enzymology / Q000235:genetics* / Q000502:physiology; D009685:Nuclear Envelope / Q000201:enzymology / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D012324:RNA-Dependent RNA Polymerase / Q000032:analysis / Q000378:metabolism*; D012098:Reproduction / Q000235:genetics; D013172:Spores, Fungal / Q000235:genetics
D004271:DNA, Fungal; D005656:Fungal Proteins; D034741:RNA, Small Interfering; D012324:RNA-Dependent RNA Polymerase