Structure and Function of the Ankyrin Repeats in the Sw14/Sw16 Transcription Complex of Budding Yeast.
Annual rept. 8 Jul 97-7 Jul 98
FRED HUTCHINSON CANCER RESEARCH CENTERSEATTLE WA
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ANK repeats were first found in the Swi6 transcription factor of Saccharomyces cerevisiae and since then were identified in many proteins, including oncogenes and tumor suppressors We have previously described generation of random mutations within the ANK repeats of SWI6 that render the protein temperature sensitive in its ability to activate HO transcription. Two of these SWI6 mutants were used in a screen for high copy suppressors of this phenotype. We found that MSN1, which encodes a transcriptional activator, and NHP6A, which encodes an HMG-like protein, are able to suppress defective Swi6 function. Both of these gene products are involved in HO transcription, and Nhp6A may also be involved in CLN1 transcription. Moreover, since overexpression of NHP6A can suppress caffeine sensitivity of one of the SWI6 ANK mutants, swi6-405, other SWI6-dependent genes may also be affected by Nhp6A. We hypothesize that Nhp6A and Msn1 modulate Swi6-dependent gene transcription indirectly, through effects on chromatin structure or other transcription factors, since we have not been able to demonstrate that either Msn1 or Nhp6A interact with the Swi4Swi6 complex.
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