search

pombase / curation

PomBase curation
7 stars 0 forks source link

cdc2, have another look at this #2573

Open ValWood opened 4 years ago

ValWood commented 4 years ago

A phosphorylation site mutant of Schizosaccharomyces pombe cdc2p fails to promote the metaphase to anaphase transition.

ValWood commented 4 years ago

PMID:9790601

ValWood commented 4 years ago

notes in e-mail:

I'm confused what I am looking at here (see attached). This is the phenotype of T167E from PMID:1655416 and Y15F/T167E from PMID:9790601

It's metaphase arrest/abolished chromosome which goes on to septate. So why does it look like most compartments have nuclei?

ValWood commented 4 years ago

Its odd, this is described in the papers as metaphase arrest. But the cells are also septated. In this case I'd expect at least some of them to be cut and they don't seem to be?

When you look at the papers, these are my annotation so far: more notes:

https://curation.pombase.org/pombe/curs/7940bef1ad8a05ee PMID:9790601 (I finished this one)

https://curation.pombase.org/pombe/curs/29300b31506c9419/ro PMID:1655416 (I'm still doing this one, and I'll finish it soon).

It would be great if you could tell me any which are clearly incorrect. Something doesn't feel right with this....but he constructs are a bit crazy anyway. sometimes there is a human CDC2 in the wt location and plasmid expression of the mutant, and for others I don't fully understand the relative contributions of the mutants so its difficult to interpret.

ValWood commented 4 years ago

I’ve just been looking at some images of cut1 and 2 required for the onset of anaphase, they septate and are have a segregation defect and long spindle. Corinne agrees with you and says that a proper metaphase arrest does not septate and cells have short spindle and a single nucleus. I wonder if these two papers mean its a defect in anaphase onset rather than a metaphase arrest and the spindle elongates but the chromosomes don’t segregate properly and get torn apart with some segregating fairly normally.

ValWood commented 4 years ago

So far, these papers seem to show that cdc2 is required for phosphorylation of APC subunit cut9.

However, to me, neither of these papers appear to show a role for cdc2 in regulating the metaphase/anaphase transition, although it might be required for the transition to occcur via a role in some upstream process which is required during metaphase.

If APC activation is a switch, which happens when the SAC is satisfied and the MCC dissociates from slp1 co-activator ....how could cdc2 have a role in activation via phosphorylation of cut9?..... It couldn't be a parallel pathway. To have a direct role in regulation it would therefore it need to be upstream of slp1 and the SAC, but cdc9 is a scaffold subunit and nowhere near the active site, or the substrate specificity parts. Perhaps it has a role in something like APC complex assembly? or liscencing, or perhaps an event required to set up inhibition of slp1....maybe the mcc binds to the APC here? although in this case I would expect different phenotypes because if the mcc could not bind to the APC you would do chromosome separation early....