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Terrell JR, Taylor SJ, Schneider AL, Lu Y, Vernon TN, Xhani S, Gumpper RH, Luo M, Wilson WD, Steidl U, Poon GMK. DNA selection by the master transcription factor PU.1. Cell Rep 2023; 42:112671. [PMID: 37352101 PMCID: PMC10479921 DOI: 10.1016/j.celrep.2023.112671] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 04/07/2023] [Accepted: 06/02/2023] [Indexed: 06/25/2023] Open
Abstract
The master transcriptional regulator PU.1/Spi-1 engages DNA sites with affinities spanning multiple orders of magnitude. To elucidate this remarkable plasticity, we have characterized 22 high-resolution co-crystallographic PU.1/DNA complexes across the addressable affinity range in myeloid gene transactivation. Over a purine-rich core (such as 5'-GGAA-3') flanked by variable sequences, affinity is negotiated by direct readout on the 5' flank via a critical glutamine (Q226) sidechain and by indirect readout on the 3' flank by sequence-dependent helical flexibility. Direct readout by Q226 dynamically specifies PU.1's characteristic preference for purines and explains the pathogenic mutation Q226E in Waldenström macroglobulinemia. The structures also reveal how disruption of Q226 mediates strand-specific inhibition by DNA methylation and the recognition of non-canonical sites, including the authentic binding sequence at the CD11b promoter. A re-synthesis of phylogenetic and structural data on the ETS family, considering the centrality of Q226 in PU.1, unifies the model of DNA selection by ETS proteins.
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Affiliation(s)
- J Ross Terrell
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
| | - Samuel J Taylor
- Departments of Cell Biology, Oncology, and Medicine, Ruth L. and David S. Gottesman Institute for Stem Cell Research and Regenerative Medicine, Blood Cancer Institute, and the Montefiore Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Amelia L Schneider
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
| | - Yue Lu
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
| | - Tyler N Vernon
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
| | - Suela Xhani
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
| | - Ryan H Gumpper
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
| | - Ming Luo
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA; Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30303, USA
| | - W David Wilson
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA; Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30303, USA
| | - Ulrich Steidl
- Departments of Cell Biology, Oncology, and Medicine, Ruth L. and David S. Gottesman Institute for Stem Cell Research and Regenerative Medicine, Blood Cancer Institute, and the Montefiore Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | - Gregory M K Poon
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA; Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30303, USA.
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Poon GMK. The Non-continuum Nature of Eukaryotic Transcriptional Regulation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1371:11-32. [PMID: 33616894 PMCID: PMC8380751 DOI: 10.1007/5584_2021_618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2024]
Abstract
Eukaryotic transcription factors are versatile mediators of specificity in gene regulation. This versatility is achieved through mutual specification by context-specific DNA binding on the one hand, and identity-specific protein-protein partnerships on the other. This interactivity, known as combinatorial control, enables a repertoire of complex transcriptional outputs that are qualitatively disjoint, or non-continuum, with respect to binding affinity. This feature contrasts starkly with prokaryotic gene regulators, whose activities in general vary quantitatively in step with binding affinity. Biophysical studies on prokaryotic model systems and more recent investigations on transcription factors highlight an important role for folded state dynamics and molecular hydration in protein/DNA recognition. Analysis of molecular models of combinatorial control and recent literature in low-affinity gene regulation suggest that transcription factors harbor unique conformational dynamics that are inaccessible or unused by prokaryotic DNA-binding proteins. Thus, understanding the intrinsic dynamics involved in DNA binding and co-regulator recruitment appears to be a key to understanding how transcription factors mediate non-continuum outcomes in eukaryotic gene expression, and how such capability might have evolved from ancient, structurally conserved counterparts.
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Affiliation(s)
- Gregory M K Poon
- Department of Chemistry, Georgia State University, Atlanta, GA, USA.
- Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, USA.
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Vo TD, Schneider AL, Wilson WD, Poon GMK. Salt bridge dynamics in protein/DNA recognition: a comparative analysis of Elk1 and ETV6. Phys Chem Chem Phys 2021; 23:13490-13502. [PMID: 34120158 PMCID: PMC8233815 DOI: 10.1039/d1cp01568k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electrostatic protein/DNA interactions arise from the neutralization of the DNA phosphodiester backbone as well as coupled exchanges by charged protein residues as salt bridges or with mobile ions. Much focus has been and continues to be paid to interfacial ion pairs with DNA. The role of extra-interfacial ionic interactions, particularly as dynamic drivers of DNA sequence selectivity, remain poorly known. The ETS family of transcription factors represents an attractive model for addressing this knowledge gap given their diverse ionic composition in primary structures that fold to a tightly conserved DNA-binding motif. To probe the importance of extra-interfacial salt bridges in DNA recognition, we compared the salt-dependent binding by Elk1 with ETV6, two ETS homologs differing markedly in ionic composition. While both proteins exhibit salt-dependent binding with cognate DNA that corresponds to interfacial phosphate contacts, their nonspecific binding diverges from cognate binding as well as each other. Molecular dynamics simulations in explicit solvent, which generated ionic interactions in agreement with the experimental binding data, revealed distinct salt-bridge dynamics in the nonspecific complexes formed by the two proteins. Impaired DNA contact by ETV6 resulted in fewer backbone contacts in the nonspecific complex, while Elk1 exhibited a redistribution of extra-interfacial salt bridges via residues that are non-conserved between the two ETS relatives. Thus, primary structure variation in ionic residues can encode highly differentiated specificity mechanisms in a highly conserved DNA-binding motif.
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Affiliation(s)
- Tam D Vo
- Department of Chemistry, Georgia State University, P.O. Box 3965, Atlanta, GA 30303, USA.
| | - Amelia L Schneider
- Department of Chemistry, Georgia State University, P.O. Box 3965, Atlanta, GA 30303, USA.
| | - W David Wilson
- Department of Chemistry, Georgia State University, P.O. Box 3965, Atlanta, GA 30303, USA. and Center for Diagnostics and Therapeutics, Georgia State University, P.O. Box 3965, Atlanta, GA 30303, USA
| | - Gregory M K Poon
- Department of Chemistry, Georgia State University, P.O. Box 3965, Atlanta, GA 30303, USA. and Center for Diagnostics and Therapeutics, Georgia State University, P.O. Box 3965, Atlanta, GA 30303, USA
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