Localization of the 26S proteasome during mitosis and meiosis in fission yeast.
The 26S proteasome is a large multisubunit complex involved in degrading both cytoplasmic and nuclear proteins. We have investigated the localization of this complex in the fission yeast, Schizosaccharomyces pombe. Immunofluorescence microscopy shows a striking localization pattern whereby the proteasome is found predominantly at the nuclear periphery, both in interphase and throughout mitosis. Electron microscopic analysis revealed a concentration of label near the inner side of the nuclear envelope. The localization of green fluorescent protein (GFP)-tagged 26S proteasomes was analyzed in live cells during mitosis and meiosis. Throughout mitosis the proteasome remained predominantly at the nuclear periphery. During meiosis the proteasome was found to undergo dramatic changes in its localization. Throughout the first meiotic division, the signal is more dispersed over the nucleus. During meiosis II, there was a dramatic re-localization, and the signal became restricted to the area between the separating DNA until the end of meiosis when the signal dispersed before returning to the nuclear periphery during spore formation. These findings strongly imply that the nuclear periphery is a major site of protein degradation in fission yeast both in interphase and throughout mitosis. Furthermore they raise interesting questions as to the spatial organization of protein degradation during meiosis.
Wilkinson
C R
CR
MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK.
Wallace
M
M
Morphew
M
M
Perry
P
P
Allshire
R
R
Javerzat
J P
JP
McIntosh
J R
JR
Gordon
C
C
D001483:Base Sequence; D002352:Carrier Proteins / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D017931:DNA Primers; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins; D008540:Meiosis; D008854:Microscopy, Electron; D008938:Mitosis; D009097:Multienzyme Complexes / Q000378:metabolism*; D009685:Nuclear Envelope / Q000201:enzymology; D046988:Proteasome Endopeptidase Complex; D012568:Schizosaccharomyces / Q000166:cytology / Q000201:enzymology* / Q000648:ultrastructure; D029702:Schizosaccharomyces pombe Proteins; D015534:Trans-Activators / Q000378:metabolism
D002352:Carrier Proteins; D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; C108670:MTS4 protein, S pombe; D009097:Multienzyme Complexes; D029702:Schizosaccharomyces pombe Proteins; D015534:Trans-Activators; C093857:rpn11 protein, S pombe; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex