The structural plasticity of SCA7 domains defines their differential nucleosome-binding properties.
SAGA (Spt-Ada-Gcn5 acetyltransferase), a coactivator complex involved in chromatin remodelling, harbours both histone acetylation and deubiquitination activities. ATXN7/Sgf73 and ATXN7L3, two subunits of the SAGA deubiquitination module, contain an SCA7 domain characterized by an atypical zinc-finger. We show that the yeast Sgf73-SCA7 domain is not required to recruit Sgf73 into SAGA. Instead, it binds to nucleosomes, a property that is conserved in the human ATXN7-SCA7 domain but is lost in the ATXN7L3 domain. The solution structures of the SCA7 domain of both ATXN7 and ATXN7L3 reveal a new, common zinc-finger motif at the heart of two distinct folds, providing a molecular basis for the observed functional differences.
Bonnet
Jacques
J
Department of Functional Genomics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS UMR 7104, INSERM U 964, Université de Strasbourg, Illkirch, France.
Wang
Ying-Hui
YH
Spedale
Gianpiero
G
Atkinson
R Andrew
RA
Romier
Christophe
C
Hamiche
Ali
A
Pijnappel
W W M Pim
WW
Timmers
H Th Marc
HT
Tora
László
L
Devys
Didier
D
Kieffer
Bruno
B
D000595:Amino Acid Sequence; D000818:Animals; D000067719:Ataxin-7; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019906:Nuclear Magnetic Resonance, Biomolecular; D009707:Nucleosomes / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination; D016335:Zinc Fingers
C000593829:ATXN7 protein, human; C527169:ATXN7L3 protein, human; D000067719:Ataxin-7; D009419:Nerve Tissue Proteins; D009707:Nucleosomes; D014157:Transcription Factors