Mixed lineage leukemia (MLL) fusion proteins cause oncogenic transformation of hematopoietic cells by constitutive recruitment of elongation factors to HOX promoters, resulting in overexpression of target genes. The structural basis of transactivation by MLL fusion partners remains undetermined. We show that the ANC1 homology domain (AHD) of AF9, one of the most common MLL translocation partners, is intrinsically disordered and recruits multiple transcription factors through coupled folding and binding. We determined the structure of the AF9 AHD in complex with the elongation factor AF4 and show that aliphatic residues, which are conserved in each of the AF9 binding partners, form an integral part of the hydrophobic core of the complex. Nuclear magnetic resonance relaxation measurements show that AF9 retains significant dynamic behavior which may facilitate exchange between disordered partners. We propose that AF9 functions as a signaling hub that regulates transcription through dynamic recruitment of cofactors in normal hematopoiesis and in acute leukemia.
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http://dx.doi.org/10.1016/j.str.2012.11.011 | DOI Listing |
Mol Cell
January 2025
Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, No. 155, Section 2, Li-nong Street, Taipei, Taiwan; Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, No. 155, Section 2, Li-nong Street, Taipei, Taiwan; Institute of Biomedical Informatics, National Yang Ming Chiao Tung University, No. 155, Section 2, Li-nong Street, Taipei, Taiwan. Electronic address:
Intrinsically disordered regions (IDRs) of proteins can regulate function through phase separation. In a recent article in Nature, Garcia-Cabau et al. reveal that including or excluding a microexon within the IDR of CPEB4 alters its condensation properties, suggesting a potential mechanism underlying autism spectrum disorder.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Department of General Surgery, The First Affiliated Hospital of University of Science and Technology of China, Key Laboratory of Immune Response and Immunotherapy, Center for Advanced Interdisciplinary Science Interdisciplinary Science & Biomedicine of Institute of Health and Medicine, Division of Life Sciences & Medicine, University of Science and Technology of China, Hefei 230027, Anhui, China.
The DNA-sensing protein cGAS plays a pivotal role in the innate immune response and pathogenesis of various diseases. DNA triggers liquid-liquid phase separation (LLPS) and enhances the enzymatic activity of cGAS. However, the regulatory mechanisms of the disordered N terminus remain unclear.
View Article and Find Full Text PDFCurr Opin Struct Biol
January 2025
Department of Medical Biochemistry and Microbiology, Uppsala University, BMC, Box 582, SE-75123 Uppsala, Sweden. Electronic address:
Protein-protein associations are often mediated by an intrinsically disordered protein region interacting with a folded domain in a coupled binding and folding reaction. Classic physical organic chemistry approaches together with structural biology have shed light on mechanistic aspects of such reactions. Further insight into general principles may be obtained by interpreting the results through an evolutionary lens.
View Article and Find Full Text PDFJ Chem Inf Model
January 2025
Max-Planck-Institut für Immunbiologie und Epigenetik (MPI-IE), Stübeweg 51, 79108 Freiburg im Breisgau, Germany.
Intrinsically disordered regions are found in most eukaryotic proteins and are enriched with positively and negatively charged residues. While it is often convenient to assume that these residues follow their model-compound p values, recent work has shown that local charge effects (charge regulation) can upshift or downshift side chain p values with major consequences for molecular function. Despite this, charge regulation is rarely considered when investigating disordered regions.
View Article and Find Full Text PDFMicrob Cell Fact
January 2025
Lab of Environmental and Life Sciences, University of Nova Gorica, Vipavska cesta 13, Nova Gorica, 5000, Slovenia.
Background: E. coli still remains the most commonly used organism to produce recombinant proteins in research labs. This condition is mirrored by the attention that researchers dedicate to understanding the biology behind protein expression, which is then exploited to improve the effectiveness of the technology.
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