High mobility group (HMG-box) genes in the honeybee fungal pathogen Ascosphaera apis

Abstract The high-mobility group (HMG) box defines a DNA-bending motif of broad interest in relation to human development and disease. Major and minor wings of an L-shaped structure provide a template for DNA bending. As in the TATA-binding protein and a diverse family of factors, insertion of one or more side chains between base pairs induces a DNA kink. The HMG box binds in the DNA minor groove and may be specific for DNA sequence or distorted DNA architecture. Whereas the angular structures of non-sequence-specific domains are well ordered, free SRY and related autosomal SOX domains are in part disordered. Observations suggesting that the minor wing lacks a fixed tertiary structure motivate the hypothesis that DNA bending and stabilization of protein structure define a coupled process. We further propose that mutual induced fit in SOX-DNA recognition underlies the sequence dependence of DNA bending and enables the induction of promoter-specific architectures.

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The RNA polymerase I transactivator upstream binding factor requires its dimerization domain and high-mobility-group (HMG) box 1 to bend, wrap, and positively supercoil enhancer DNA.

Molecular and Cellular Biology ◽

10.1128/mcb.14.10.6476 ◽

1994 ◽

Vol 14 (10) ◽

pp. 6476-6488 ◽

Cited By ~ 38

Author(s):

C D Putnam ◽

G P Copenhaver ◽

M L Denton ◽

C S Pikaard

Keyword(s):

Rna Polymerase ◽

High Mobility ◽

Rna Polymerase I ◽

High Mobility Group ◽

Dna Ligase ◽

Dimerization Domain ◽

Hmg Box ◽

Binding Factor ◽

Upstream Binding Factor ◽

Polymerase I

Upstream binding factor (UBF) is an important transactivator of RNA polymerase I and is a member of a family of proteins that contain nucleic acid binding domains named high-mobility-group (HMG) boxes because of their similarity to HMG chromosomal proteins. UBF is a highly sequence-tolerant DNA-binding protein for which no binding consensus sequence has been identified. Therefore, it has been suggested that UBF may recognize preformed structural features of DNA, a hypothesis supported by UBF's ability to bind synthetic DNA cruciforms, four-way junctions, and even tRNA. We show here that full-length UBF can also bend linear DNA to mediate circularization of probes as small as 102 bp in the presence of DNA ligase. Longer probes in the presence of UBF become positively supercoiled when ligated, suggesting that UBF wraps the DNA in a right-handed direction, opposite the direction of DNA wrapping around a nucleosome. The dimerization domain and HMG box 1 are necessary and sufficient to circularize short probes and supercoil longer probes in the presence of DNA ligase. UBF's sequence tolerance coupled with its ability to bend and wrap DNA makes UBF an unusual eukaryotic transcription factor. However, UBF's ability to bend DNA might explain how upstream and downstream rRNA gene promoter domains interact. UBF-induced DNA wrapping could also be a mechanism by which UBF counteracts histone-mediated gene repression.

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Ste11p, a High-Mobility-Group Box DNA-Binding Protein, Undergoes Pheromone- and Nutrient-Regulated Nuclear-Cytoplasmic Shuttling

Molecular and Cellular Biology ◽

10.1128/mcb.23.9.3253-3264.2003 ◽

2003 ◽

Vol 23 (9) ◽

pp. 3253-3264 ◽

Cited By ~ 23

Author(s):

Jian Qin ◽

Wenfei Kang ◽

Betty Leung ◽

Maureen McLeod

Keyword(s):

Dna Binding ◽

Dna Sequences ◽

Nuclear Export ◽

Cellular Localization ◽

Nuclear Export Signal ◽

High Mobility ◽

High Mobility Group ◽

Nuclear Accumulation ◽

Leptomycin B ◽

Hmg Box

ABSTRACT The high-mobility-group (HMG) box is a conserved DNA-binding domain found in a family of transcription factors that regulate growth and development. One family member, Ste11p, directs sexual differentiation of Schizosaccharomyces pombe by binding specific DNA sequences upstream of genes required for mating and meiosis. Here, we show that Ste11p is a shuttling protein. In growing cells, Ste11p is present in low levels and is pancellular. Mating pheromones and nutrient limitation trigger nuclear accumulation and increased expression of the transcription factor. Several mechanisms likely control Ste11p localization. First, the 14-3-3 protein, Rad24p, binds phosphorylated Ste11p and inhibits its nuclear accumulation. Second, the HMG domain of Ste11p contains a basic cluster nuclear localization signal. Finally, treatment of cells with leptomycin B, an exportin inhibitor, results in the nuclear accumulation of Ste11p. A Ste11p deletion mutation, ΔC54, mimics the effects of leptomycin B. The C54 region contains no identifiable nuclear export signal but instead is required for biological activity and to stimulate Ste11p target gene expression. These results provide evidence that both nuclear import and export mechanisms operate to regulate cellular localization of an HMG box protein. In addition, they establish a paradigm for the potential role of pheromone/hormone-like polypeptides in cellular localization of this important class of developmental regulators.

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TOX as a potential target for immunotherapy in lymphocytic malignancies

Biomarker Research ◽

10.1186/s40364-021-00275-y ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Chaofeng Liang ◽

Shuxin Huang ◽

Yujie Zhao ◽

Shaohua Chen ◽

Yangqiu Li

Keyword(s):

T Cell ◽

Potential Role ◽

Hematological Malignancies ◽

High Mobility ◽

High Mobility Group ◽

Biological Functions ◽

Hmg Box ◽

Cell Exhaustion ◽

Potential Target

AbstractTOX (thymocyte selection-associated HMG BOX) is a member of a family of transcriptional factors that contain the highly conserved high mobility group box (HMG-box) region. Increasing studies have shown that TOX is involved in maintaining tumors and promoting T cell exhaustion. In this review, we summarized the biological functions of TOX and its contribution as related to lymphocytic malignancies. We also discussed the potential role of TOX as an immune biomarker and target in immunotherapy for hematological malignancies.

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