ZnF_TAZTAZ zinc finger, present in p300 and CBP
|SMART accession number:||SM00551|
|Interpro abstract (IPR000197):|
Zinc finger (Znf) domains are relatively small protein motifs which contain multiple finger-like protrusions that make tandem contacts with their target molecule. Some of these domains bind zinc, but many do not; instead binding other metals such as iron, or no metal at all. For example, some family members form salt bridges to stabilise the finger-like folds. They were first identified as a DNA-binding motif in transcription factor TFIIIA from Xenopus laevis (African clawed frog), however they are now recognised to bind DNA, RNA, protein and/or lipid substrates [(PUBMED:10529348), (PUBMED:15963892), (PUBMED:15718139), (PUBMED:17210253), (PUBMED:12665246)]. Their binding properties depend on the amino acid sequence of the finger domains and of the linker between fingers, as well as on the higher-order structures and the number of fingers. Znf domains are often found in clusters, where fingers can have different binding specificities. There are many superfamilies of Znf motifs, varying in both sequence and structure. They display considerable versatility in binding modes, even between members of the same class (e.g. some bind DNA, others protein), suggesting that Znf motifs are stable scaffolds that have evolved specialised functions. For example, Znf-containing proteins function in gene transcription, translation, mRNA trafficking, cytoskeleton organisation, epithelial development, cell adhesion, protein folding, chromatin remodelling and zinc sensing, to name but a few [(PUBMED:11179890)]. Zinc-binding motifs are stable structures, and they rarely undergo conformational changes upon binding their target.
TAZ (Transcription Adaptor putative Zinc finger) domains are zinc-containing domains found in the homologous transcriptional co-activators CREB-binding protein (CBP) and the P300. CBP and P300 are histone acetyltransferases (EC 22.214.171.124) that catalyse the reversible acetylation of all four histones in nucleosomes, acting to regulate transcription via chromatin remodelling. These large nuclear proteins interact with numerous transcription factors and viral oncoproteins, including p53 tumour suppressor protein, E1A oncoprotein, MyoD, and GATA-1, and are involved in cell growth, differentiation and apoptosis [(PUBMED:8848831)]. Both CBP and P300 have two copies of the TAZ domain, one in the N-terminal region, the other in the C-terminal region. The TAZ1 domain of CBP and P300 forms a complex with CITED2 (CBP/P300-interacting transactivator with ED-rich tail), inhibiting the activity of the hypoxia inducible factor (HIF-1alpha) and thereby attenuating the cellular response to low tissue oxygen concentration [(PUBMED:12778114)]. Adaptation to hypoxia is mediated by transactivation of hypoxia-responsive genes by hypoxia-inducible factor-1 (HIF-1) in complex with the CBP and p300 transcriptional coactivators [(PUBMED:11959990)].
The TAZ domain adopts an all-alpha fold with zinc-binding sites in the loops connecting the helices. The TAZ1 domain in P300 and the TAZ2 (CH3) domain in CBP have each been shown to have four amphipathic helices, organised by three zinc-binding clusters with HCCC-type coordination [(PUBMED:11023789), (PUBMED:14594809), (PUBMED:15641773)].
More information about these proteins can be found at Protein of the Month: Zinc Fingers .
|GO process:||regulation of transcription, DNA-dependent (GO:0006355)|
|GO component:||nucleus (GO:0005634)|
|GO function:||histone acetyltransferase activity (GO:0004402), transcription cofactor activity (GO:0003712), zinc ion binding (GO:0008270)|
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