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Published on: December 20, 2010
Structural studies of a four-MBT repeat protein MBTD1
Jitka Eryilmaz1, Patricia Pan, Maria F Amaya
1Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada.
Plos One
|October 21, 2009
Summary
Malignant Brain Tumor domain-containing protein 1 (MBTD1) binds mono- and di-methylated lysine histones. Its crystal structure reveals an asymmetric architecture, similar to other MBT repeat proteins, utilizing a semi-aromatic cage for binding.
Area of Science:
- Structural Biology
- Epigenetics
- Protein Biochemistry
Background:
- Polycomb group (PcG) proteins regulate gene transcription during development.
- MBTD1, a PcG protein, features four Malignant Brain Tumor (MBT) repeats.
- MBTD1's role in transcriptional repression is linked to its MBT repeats.
Purpose of the Study:
- To determine the crystal structure of MBTD1.
- To investigate MBTD1's histone binding preferences.
- To elucidate the structural basis of MBTD1-histone interactions.
Main Methods:
- X-ray crystallography to determine MBTD1 structure (residues 130-566).
- Fluorescence polarization assays to assess histone peptide binding.
- Site-directed mutagenesis to probe MBT repeat function.
Main Results:
- The crystal structure of MBTD1 (4 MBT repeats) was solved at 2.5 Å resolution.
- MBTD1 preferentially binds mono- and di-methylated lysine histone peptides.
- MBTD1 shares structural similarity with L3MBTL2, another MBT repeat protein.
Conclusions:
- MBTD1 possesses an asymmetric rhomboid architecture formed by its four MBT repeats.
- MBTD1 binds methylated lysine histones via a semi-aromatic cage within one MBT repeat.
- This binding mechanism is conserved among characterized MBT repeat proteins.
