Rsp1p, a J domain protein required for disassembly and assembly of microtubule organizing centers during the fission yeast cell cycle.
Regulation of microtubule organizing centers (MTOCs) orchestrates the reorganization of the microtubule (MT) cytoskeleton. In the fission yeast Schizosaccharomyces pombe, an equatorial MTOC (eMTOC) at the cell division site disassembles after cytokinesis, and multiple interphase MTOCs (iMTOCs) appear on the nucleus. Here, we show that, upon eMTOC disassembly, small satellites carrying MTOC components such as the gamma-tubulin complex travel in both directions along interphase MTs. We identify rsp1p, an MTOC protein required for eMTOC disassembly. In rsp1 loss-of-function mutants, the eMTOC persists and organizes an abnormal microtubule aster, while iMTOCs and satellites are greatly reduced. Conversely, rsp1p overexpression inhibits eMTOC formation. Rsp1p is a J domain protein that interacts with an hsp70. Thus, our findings suggest a model in which rsp1p is part of a chaperone-based mechanism that disassembles the eMTOC into satellites, contributing to the dynamic redistribution of MTOC components for organization of interphase microtubules.
Results
Fig. 1
[x] rsp1-1 (P41L):
[x] Deffective septum positioning, but vertical
[x] normal temp - Low penetrance branched, bent, round
[x] 35 C severe morphological deffects, unviable
[x] Mispositioned nucleus in 30% of the cells at 30
[x] Mispositioned nucleus in 60% of cells at 37 (not sure how they would measure that in such weird cells)
[x] Single MT bundle in 64% of cells -> aster like
[x] Normal MT dynamics
[x] Bundles disconnected from the nucleus
[x] Co-IP rps1 and ssa1
[x] rsp1-1/rsp1+ rforms normal MT arrays (rsp1-1 is recessive)
[x] rsp1D milder phenotypes:
[x] Nuclear pos errors 10%
[x] Lower number of bundles (typically 2, vs 3-5 in wt), but not single aster-like
Fig. 2 and 3
[x] rsp1-1
[x] abolished disassembly of the eMTOC 61%
[x] Increased recruitment of alp4-GFP to the septum (2x)
[x] premature assembly of the eMTOC (spindles of 6 um instead of 12 um -wild type-)
[x] Sometimes the previous eMTOC persisted until the next cytok. and would form the array.
[x] rsp1D
[x] abolished disassembly of the eMTOC 30%
Fig. 4 and 5
[x] rsp1 localization:
[x] interphase: SPB, perinuclear dots (iMTOC), along MTs
[x] mitosis: SPBs and eMTOCs
[ ]
Fig. 6
[x] rsp1D and rsp1-1
[x] Loss of alp4 localization to microtubule body 77% rsp1D 84% rsp1-1
[x] alp4 localizes to iMTOCs only during interphase
Fig. 7
[x] rsp1 OE:
[x] eMTOC formation inhibited 100%
[x] nucleus mispositioned 70%
[x] Decreased number of bundles to 2-1
[x] Alp4 absent or greatly reduced from septum at late anaphase
PMID:15068790
Rsp1p, a J domain protein required for disassembly and assembly of microtubule organizing centers during the fission yeast cell cycle.
Regulation of microtubule organizing centers (MTOCs) orchestrates the reorganization of the microtubule (MT) cytoskeleton. In the fission yeast Schizosaccharomyces pombe, an equatorial MTOC (eMTOC) at the cell division site disassembles after cytokinesis, and multiple interphase MTOCs (iMTOCs) appear on the nucleus. Here, we show that, upon eMTOC disassembly, small satellites carrying MTOC components such as the gamma-tubulin complex travel in both directions along interphase MTs. We identify rsp1p, an MTOC protein required for eMTOC disassembly. In rsp1 loss-of-function mutants, the eMTOC persists and organizes an abnormal microtubule aster, while iMTOCs and satellites are greatly reduced. Conversely, rsp1p overexpression inhibits eMTOC formation. Rsp1p is a J domain protein that interacts with an hsp70. Thus, our findings suggest a model in which rsp1p is part of a chaperone-based mechanism that disassembles the eMTOC into satellites, contributing to the dynamic redistribution of MTOC components for organization of interphase microtubules.
Results
Fig. 1
Fig. 2 and 3
Fig. 4 and 5
Fig. 6
Fig. 7
FYPO
GO
Existing annotations.
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