The SCAN Domain of ZNF174 Is a Dimer

Abstract

The SCAN domain is a conserved region of 84 residues found predominantly in zinc finger DNA-binding proteins in vertebrates. The SCAN domain appears to control the association of SCAN domain containing proteins into noncovalent complexes and may be the primary mechanism underlying partner choice in the oligomerization of these transcription factors. Here we have overexpressed, purified, and characterized the isolated SCAN domain (amino acids 37-132) from ZNF174. Both size exclusion chromatography and equilibrium sedimentation analysis demonstrate that the ZNF174 SCAN domain forms a homodimer. Circular dichroism shows that the isolated SCAN domain dimer has ϳ42% ␣-helix. Thermal denaturation experiments indicate that the SCAN domain undergoes a single reversible unfolding transition with a T m of over 70°C. The midpoint of the equilibrium unfolding transition increases with increasing protein concentration, consistent with a two-state unfolding transition in which folded dimer is in equilibrium with unfolded monomer. These findings demonstrate that the isolated SCAN domain forms a stable dimer and support a model in which the SCAN domain is capable of mediating the selective dimerization of a large family of vertebrate-specific, zinc finger-containing transcription factors.Transcription factors are composed of modular elements that include a DNA-binding domain and one or more separable effector domains that activate or repress transcription. Other modules within these factors regulate subcellular localization and gene expression by mediating selective association of the transcription factors with each other, or with other cellular components. Identification of these domains often provides a conceptual framework for understanding the function of the transcription factor.The SCAN 1 domain is a highly conserved vertebrate-specific protein domain found in ϳ60 genes in the human genome (1, 2). Only a handful of these gene products have been characterized thus far, and they appear to control a wide range of biological processes including development, cell differentiation, and lipid metabolism (reviewed in Refs. 3 and 4). The name for the SCAN domain was derived from the first letters of the names of four proteins initially found to contain this domain (SRE-ZBP, CTfin51, AW-1 (ZNF174), and Number 18 cDNA or ZNF197) (5). Alternatively, this domain has been referred to as LeR for leucine-rich domain (6). The SCAN domain consists of an 84-residue, leucine-rich region and is predicted to contain a high degree of ␣-helix. It is located at the N terminus when it is part of a zinc finger-containing transcription factor. The primary amino acid sequence of the domain does not resemble any of the other zinc finger-associated domains, such as the Kruppelassociated box (KRAB) or the poxvirus and zinc finger (POZ) domain, which is also known as the BTB (Broad-complex, Tramtrack, and Bric-a-brac) domain (7-9). Members of the SCAN domain family are broadly expressed and appear to function as either activators or repressors of transcri...

Repression of Vascular Endothelial Growth Factor Expression by the Zinc Finger Transcription Factor ZNF24

“…For example, ZNF24 may bind the VEGF promoter directly either by itself, as part of a transcriptional repression complex, or indirectly as part of a complex that binds the promoter via one of the other molecules comprising that complex. The N-terminal region of ZNF24 contains a SCAN box domain, a leucine-rich domain that has been implicated as an oligomerization domain mediating protein-protein interactions to form homoligomers or heteroligomers with other proteins containing SCAN domains (24)(25)(26). Therefore, it is possible that ZNF24 comprises part of a transcriptional repression complex that binds the VEGF promoter via the DNA-binding domains of ZNF24 and/ or other potential DNA-binding molecules within the complex.…”

ZFP191 is required by oligodendrocytes for CNS myelination

“…The SCAN domain is a leucinerich domain that is capable of facilitating protein-protein interactions (Stone et al 2002;Edelstein and Collins 2005;Peterson et al 2006). This subset of zinc finger proteins exists only in the mammalian lineage, indicating that they evolved relatively recently (Edelstein and Collins 2005).…”

Establishment of transgenic mice carrying gene encoding human zinc finger protein 191

“…This first identification suggested that ZNF191 played a role in hematopoiesis. ZNF191 has been found to contain a SCAN domain mediating selective protein oligomerization [6][7][8] . ZNF191 specifically binds to HUMTH01 in vitro.…”

“…ZNF191 is a putative transcription factor belonging to Krüppel-like zinc finger gene family. It contains four Cys 2 /His 2 zinc fingers in its C-terminus, and one SCAN box element (also known as LeR domain for leucine-rich) in its N-terminus [5][6][7] . Biochemical binding studies showed SCAN as a selective heterologous and homologous oligomerization domain [7,8] .…”

“…It contains four Cys 2 /His 2 zinc fingers in its C-terminus, and one SCAN box element (also known as LeR domain for leucine-rich) in its N-terminus [5][6][7] . Biochemical binding studies showed SCAN as a selective heterologous and homologous oligomerization domain [7,8] . Tissue mRNA analysis showed that ZNF191 gene was ubiquitously expressed [5,9] .…”