Molecular analysis of KTI12/TOT4, a Saccharomyces cerevisiae gene required for Kluyveromyces lactis zymocin action.
TOT, the putative Kluyveromyces lactis zymocin target complex from Saccharomyces cerevisiae, is encoded by TOT1-7, six loci of which are isoallelic to RNA polymerase II (RNAPII) Elongator genes (ELP1-6). Unlike TOT1-3 (ELP1-3) and TOT5-7 (ELP5, ELP6 and ELP4 respectively), which display zymocin resistance when deleted, TOT4 (KTI12) also renders cells refractory to zymocin when maintained in multicopy or overexpressed from the GAL10 promoter. Elevated TOT4 copy number results in an intermediate tot phenotype, which includes mild sensitivities towards caffeine, Calcofluor white and elevated growth temperature, suggesting that TOT4 influences TOT/Elongator function. Tot4p interacts with Elongator, as shown by co-immunoprecipitation, and cell fractionation studies demonstrate partial co-migration with RNAPII and Elongator. As Elongator subunit interaction is not affected by either deletion of TOT4 or multicopy TOT4, Tot4p may not be a structural Elongator subunit but, rather, may regulate TOT/Elongator in a fashion that requires transient physical contact with TOT/Elongator. Consistent with a regulatory role, the presence of a potential P-loop motif conserved between yeast and human TOT4 homologues suggests capability of ATP or GTP binding and P-loop deletion renders Tot4p biologically inactive.
Fichtner
Lars
L
Institut für Genetik, Martin-Luther-Universität Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany.
Frohloff
Frank
F
Bürkner
Konstanze
K
Larsen
Michael
M
Breunig
Karin D
KD
Schaffrath
Raffael
R
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D018628:Gene Dosage; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase; D055646:Killer Factors, Yeast; D007716:Kluyveromyces / Q000235:genetics / Q000378:metabolism*; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009183:Mycotoxins / Q000235:genetics / Q000378:metabolism*; D011496:Protein Methyltransferases; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid
D048868:Adaptor Proteins, Signal Transducing; D005656:Fungal Proteins; C088889:KTI12 protein, S cerevisiae; D055646:Killer Factors, Yeast; D009183:Mycotoxins; D029701:Saccharomyces cerevisiae Proteins; C058975:zymocin; D000076983:Histone Methyltransferases; D008780:Methyltransferases; D011496:Protein Methyltransferases; D011495:Histone-Lysine N-Methyltransferase; D012319:RNA Polymerase II