HMG-box

In molecular biology, the HMG-box (high mobility group box) is a protein domain which is involved in DNA binding.[1] The domain is composed of approximately 75 amino acid residues that collectively mediate the DNA-binding of chromatin-associated high-mobility group proteins. HMG-boxes are present in many transcription factors and chromatin-remodeling complexes, where they can mediate non-sequence or sequence-specific DNA binding.[2]

HMG (high mobility group) box
NMR structure of the HMG-box domain of the LEF1 protein (rainbow colored, N-terminus = blue, C-terminus = red) complexed with DNA (brown) based on the PDB: 2LEF​ coordinates.
Identifiers
SymbolPF00505
PfamPF00505
InterProIPR009071
SCOP21hsm / SCOPe / SUPFAM
Available protein structures:
Pfam  structures / ECOD  
PDBRCSB PDB; PDBe; PDBj
PDBsumstructure summary
PDB1aab​, 1cg7​, 1ckt​, 1e7j​, 1gt0​, 1hme​, 1hmf​, 1hry​, 1hrz​, 1hsm​, 1hsn​, 1i11​, 1j3x​, 1j46​, 1j47​, 1j5n​, 1k99​, 1lwm​, 1nhm​, 1nhn​, 1o4x​, 1qrv​, 1s9m​, 1sx9​, 1v64​, 1wgf​, 1wxl​, 2crj​, 2cs1​, 2lef​

Structure

The structure of the HMG-box domain contains three alpha helices separated by loops (see figure to the right).[3]

Function

HMG-box containing proteins only bind non-B-type DNA conformations (kinked or unwound) with high affinity.[1] HMG-box domains are found in some high mobility group proteins, which are involved in the regulation of DNA-dependent processes such as transcription, replication, and DNA repair, all of which require changing the conformation of chromatin.[3] The single and the double box HMG proteins alter DNA architecture by inducing bends upon binding.[4][5]

References
  1. Stros M, Launholt D, Grasser KD (October 2007). "The HMG-box: a versatile protein domain occurring in a wide variety of DNA-binding proteins". Cell. Mol. Life Sci. 64 (19–20): 2590–606. doi:10.1007/s00018-007-7162-3. PMID 17599239. S2CID 28156847.
  2. Štros, M.; Launholt, D.; Grasser, K. D. (October 2007). "The HMG-box: a versatile protein domain occurring in a wide variety of DNA-binding proteins". Cellular and Molecular Life Sciences. 64 (19–20): 2590–2606. doi:10.1007/s00018-007-7162-3. Retrieved 18 February 2023.
  3. Thomas JO (August 2001). "HMG1 and 2: architectural DNA-binding proteins". Biochem. Soc. Trans. 29 (Pt 4): 395–401. doi:10.1042/BST0290395. PMID 11497996.
  4. D. Murugesapillai et al, DNA bridging and looping by HMO1 provides a mechanism for stabilizing nucleosome-free chromatin, Nucleic Acids Res (2014) 42 (14): 8996-9004
  5. D. Murugesapillai et al, Single-molecule studies of high-mobility group B architectural DNA bending proteins, Biophys Rev (2016) doi:10.1007/s12551-016-0236-4
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