BTB domain (POZ domain) in many POX virus ZNF proteins, ( virulence factor )
(BTB= bric-à-brac, tramtrack and broad complex transcription regulators
https://genomebiology.biomedcentral.com/articles/10.1186/gb-2005-6-10-r82
BTB domain, Vihkoon aloitettu tästä piirtää kaavakuvia. 1.4. 2022
Kesken. Uusi vihko. Kertaan nyt POX viruksen virulenssitekijöitä ja niiden TR jaksoja kuten KELCH tai ANK 13.10.2025
2. Olen lukemassa tätä artikkelia alla.
BTB-domain proteins12005
https://genomebiology.biomedcentral.com/articles/10.1186/gb-2005-6-10-r82
Research Open Access Published: 15 SeptembeSequence and structural analysis of BTB domain proteins Peter J Stogios, Genome Biology volume 6, Article number: R82 (2005) Cite this article Abstract
Background
The BTB domain (also known as the POZ domain) is a versatile protein-protein interaction motif that participates in a wide range of cellular functions, including transcriptional regulation, cytoskeleton dynamics, ion channel assembly and gating, and targeting proteins for ubiquitination. Several BTB domain structures have been experimentally determined, revealing a highly conserved core structure.
Results
We surveyed the protein architecture, genomic distribution and sequence conservation of BTB domain proteins in 17 fully sequenced eukaryotes. The BTB domain is typically found as a single copy in proteins that contain only one or two other types of domain, and this defines the BTB-zinc finger (BTB-ZF), BTB-BACK-kelch (BBK), voltage-gated potassium channel T1 (T1-Kv), MATH-BTB, BTB-NPH3 and BTB-BACK-PHR (BBP) families of proteins, among others. In contrast, the Skp1 and ElonginC proteins consist almost exclusively of the core BTB fold. There are numerous lineage-specific expansions of BTB proteins, as seen by the relatively large number of BTB-ZF and BBK proteins in vertebrates, MATH-BTB proteins in Caenorhabditis elegans, and BTB-NPH3 proteins in Arabidopsis thaliana. Using the structural homology between Skp1 and the PLZF BTB homodimer, we present a model of a BTB-Cul3 SCF-like E3 ubiquitin ligase complex that shows that the BTB dimer or the T1 tetramer is compatible in this complex. Conclusion Despite widely divergent sequences, the BTB fold is structurally well conserved. The fold has adapted to several different modes of self-association and interactions with non-BTB proteins.
Background
The BTB domain (also known as the POZ domain) was originally identified as a conserved motif present in the Drosophila melanogaster bric-à-brac, tramtrack and broad complex transcription regulators and in many pox virus zinc finger proteins [1–4]. A variety of functional roles have been identified for the domain, including transcription repression [5, 6], cytoskeleton regulation [7–9], tetramerization and gating of ion channels [10, 11] and protein ubiquitination/degradation [12–17]. Recently, BTB proteins have been identified in screens for interaction partners of the Cullin (Cul)3 Skp1-Cullin-F-box (SCF)-like E3 ubiquitin ligase complex, with the BTB domain mediating recruitment of the substrate recognition modules to the Cul3 component of the SCF-like complex [18–20]. In most of these functional classes, the BTB domain acts as a protein-protein interaction module that is able to both self-associate and interact with non-BTB proteins.
Several BTB structures have been determined by X-ray crystallography, establishing the structural similarity between different examples of the fold. We use the Structural Classification of Proteins (SCOP) database terminology of 'fold' to describe the set of BTB sequences that are known or predicted to share a secondary structure arrangement and topology, and the term 'family' to describe more highly related sequences that are likely to be functionally similar [21]. Thus, the BTB domain in BTB-zinc finger (ZF), Skp1, ElonginC and voltage-gated potassium channel T1 (T1-Kv) proteins all contain the BTB fold, even though some of these differ in their peripheral secondary structure elements and are involved in different types of protein-protein associations. For example, BTB domains from the BTB-ZF family contain an amino-terminal extension and form homodimers [5, 22], whereas the Skp1 proteins contain a family-specific carboxy-terminal extension and occur as single copies in heterotrimeric SCF complexes [23–26]. The ElonginC proteins are also involved in protein degradation pathways, although these proteins consist only of the core BTB fold and are typically less than 20% identical to the Skp1 proteins [27, 28]. Finally, T1 domains in T1-Kv proteins consist only of the core fold and associate into homotetramers [11, 29]. Thus, while the structures of BTB domains show good conservation in overall tertiary structure, there is little sequence similarity between members of different families. As a result, the BTB fold is a versatile scaffold that participates in a variety of types of family-specific protein-protein interactions.
Given the range of functions, structures and interactions mediated by BTB domains, we undertook a survey of the abundance, protein architecture, conservation and structure of this fold. An earlier study [30] is consistent with many of the results presented here, and we contribute an expanded structure and genome-centric analysis of BTB domain proteins, with an emphasis on the scope of protein-protein interactions in these proteins. Our results should be useful for the structural and functional prediction by analogy for some of the less-well characterized BTB domain families.
Results and discussion
BTB fold comparisons
We began our analysis with a comparison of the solved structures of BTB domains from the Protein Data Bank (PDB) [31], which included examples from BTB-ZF proteins, Skp1, ElonginC and T1 domains (Figures 1, 2, 3). A three-dimensional superposition showed a common region of
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