Characterization of yeast histone H3-specific type B histone acetyltransferases identifies an ADA2-independent Gcn5p activity.
BACKGROUND
The acetylation of the core histone NH2-terminal tails is catalyzed by histone acetyltransferases. Histone acetyltransferases can be classified into two distinct groups (type A and B) on the basis of cellular localization and substrate specificity. Type B histone acetyltransferases, originally defined as cytoplasmic enzymes that acetylate free histones, have been proposed to play a role in the assembly of chromatin through the acetylation of newly synthesized histones H3 and H4. To date, the only type B histone acetyltransferase activities identified are specific for histone H4.


RESULTS
To better understand the role of histone acetylation in the assembly of chromatin structure, we have identified additional type B histone acetyltransferase activities specific for histone H3. One such activity, termed HatB3.1, acetylated histone H3 with a strong preference for free histones relative to chromatin substrates. Deletion of the GCN5 and ADA3 genes resulted in the loss of HatB3.1 activity while deletion of ADA2 had no effect. In addition, Gcn5p and Ada3p co-fractionated with partially purified HatB3.1 activity while Ada2p did not.


CONCLUSIONS
Yeast extracts contain several histone acetyltransferase activities that show a strong preference for free histone H3. One such activity, termed HatB3.1, appears to be a novel Gcn5p-containing complex which does not depend on the presence of Ada2p.
Department of Molecular and Cellular Biochemistry, College of Medicine and Public Health, The Ohio State University, Columbus, OH 43210, USA. sklenar.39@osu.edu
Amy R
AR
Sklenar
Mark R
MR
Parthun
D000123:Acetyltransferases / Q000737:chemistry / Q000378:metabolism*; D020134:Catalytic Domain; D002467:Cell Nucleus / Q000201:enzymology; D002852:Chromatography, Ion Exchange; D003600:Cytosol / Q000201:enzymology; D004268:DNA-Binding Proteins / Q000378:metabolism; D051548:Histone Acetyltransferases; D006657:Histones / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D013379:Substrate Specificity; D014157:Transcription Factors / Q000378:metabolism; D000099224:p300-CBP-Associated Factor
D000123:Acetyltransferases; D004268:DNA-Binding Proteins; D051548:Histone Acetyltransferases; D006657:Histones; D011494:Protein Kinases; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C090575:ADA2 protein, S cerevisiae; C083323:NGG1 protein, S cerevisiae; C501392:GCN5 protein, S cerevisiae; D000099224:p300-CBP-Associated Factor