Wenyi,
> I have a what might appear to be galactically stupid question: is
> MEC1 essential for viability in budding yeast? I have seen different
> reports and am genuinely confused. I'd appreciate it if someone could
> explain to me.
It's complicated. But a complete deletion of MEC1 and the mec1-1
point mutation are lethal in an otherwise wild type background. A
suppressor, sml1-1, was found to be segregating in the mec1-1
isolate that suppressed the lethality. It also suppresses a mec1
knockout, so it's not allele-specific. It is thought that the wild type
Sml1 protein inhibits dNTP synthesis and that this is lethal in
mec1 mutants because DNA synthesis cannot proceed.
Furthermore, overexpression of downstream checkpoint kinases
RAD53 and DUN1, or the paralogous ATM-like kinase TEL1, can
suppress the lethality of MEC1. See Zhao et al., Molecular Cell 2:
329-340, 1998, and references therein. Hope this helps.
Beth A. Montelone, Ph. D, Associate Professor
Division of Biology, Ackert Hall
Kansas State University
Manhattan, KS 66506-4901
phone (785) 532-6092; fax (785) 532-6653
web site http://www-personal.ksu.edu/~bethmont
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