1
|
Harris EL, Roy V, Montagne M, Rose AMS, Livesey H, Reijnders MRF, Hobson E, Sansbury FH, Willemsen MH, Pfundt R, Warren D, Long V, Carr IM, Brunner HG, Sheridan EG, Firth HV, Lavigne P, Poulter JA. A recurrent de novo MAX p.Arg60Gln variant causes a syndromic overgrowth disorder through differential expression of c-Myc target genes. Am J Hum Genet 2024; 111:119-132. [PMID: 38141607 PMCID: PMC10806738 DOI: 10.1016/j.ajhg.2023.11.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 11/23/2023] [Accepted: 11/29/2023] [Indexed: 12/25/2023] Open
Abstract
Cyclin D2 (CCND2) stabilization underpins a range of macrocephaly-associated disorders through mutation of CCND2 or activating mutations in upstream genes encoding PI3K-AKT pathway components. Here, we describe three individuals with overlapping macrocephaly-associated phenotypes who carry the same recurrent de novo c.179G>A (p.Arg60Gln) variant in Myc-associated factor X (MAX). The mutation, located in the b-HLH-LZ domain, causes increased intracellular CCND2 through increased transcription but it does not cause stabilization of CCND2. We show that the purified b-HLH-LZ domain of MAXArg60Gln (Max∗Arg60Gln) binds its target E-box sequence with a lower apparent affinity. This leads to a more efficient heterodimerization with c-Myc resulting in an increase in transcriptional activity of c-Myc in individuals carrying this mutation. The recent development of Omomyc-CPP, a cell-penetrating b-HLH-LZ-domain c-Myc inhibitor, provides a possible therapeutic option for MAXArg60Gln individuals, and others carrying similar germline mutations resulting in dysregulated transcriptional c-Myc activity.
Collapse
Affiliation(s)
- Erica L Harris
- Division of Molecular Medicine, Leeds Institute of Medical Research, University of Leeds, Leeds, UK
| | - Vincent Roy
- Département de Biochimie et Génomique Fonctionnelle, PROTÉO et Institut de Pharmacologie de Sherbrooke. University of Sherbrooke, Sherbrooke, QC, Canada
| | - Martin Montagne
- Département de Biochimie et Génomique Fonctionnelle, PROTÉO et Institut de Pharmacologie de Sherbrooke. University of Sherbrooke, Sherbrooke, QC, Canada
| | - Ailsa M S Rose
- Division of Molecular Medicine, Leeds Institute of Medical Research, University of Leeds, Leeds, UK
| | - Helen Livesey
- Leeds Teaching Hospitals NHS Trust, Leeds, UK; All Wales Medical Genomics Service, NHS Wales Cardiff and Vale University Health Board, Cardiff, UK
| | - Margot R F Reijnders
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Emma Hobson
- Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - Francis H Sansbury
- All Wales Medical Genomics Service, NHS Wales Cardiff and Vale University Health Board, Cardiff, UK
| | - Marjolein H Willemsen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Rolph Pfundt
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | | | - Vernon Long
- Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - Ian M Carr
- Division of Molecular Medicine, Leeds Institute of Medical Research, University of Leeds, Leeds, UK
| | - Han G Brunner
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Eamonn G Sheridan
- Division of Molecular Medicine, Leeds Institute of Medical Research, University of Leeds, Leeds, UK; Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - Helen V Firth
- Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK; Wellcome Sanger Institute, Hinxton, Cambridge, UK
| | - Pierre Lavigne
- Département de Biochimie et Génomique Fonctionnelle, PROTÉO et Institut de Pharmacologie de Sherbrooke. University of Sherbrooke, Sherbrooke, QC, Canada.
| | - James A Poulter
- Division of Molecular Medicine, Leeds Institute of Medical Research, University of Leeds, Leeds, UK.
| |
Collapse
|
2
|
Inamoto I, Sheoran I, Popa SC, Hussain M, Shin JA. Combining Rational Design and Continuous Evolution on Minimalist Proteins That Target the E-box DNA Site. ACS Chem Biol 2021; 16:35-44. [PMID: 33370105 DOI: 10.1021/acschembio.0c00684] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Protein-based therapeutics are part of the next-generation arsenal of drugs being developed against proto-oncoprotein Myc. We designed protein MEF to mimic the basic region/helix-loop-helix/leucine zipper (bHLHZ) domain of Max and Myc, which bind to the E-box motif (enhancer box, CACGTG). To make MEF, we started with our rationally designed ME47, a hybrid of the Max basic region and E47 HLH, that effectively inhibited tumor growth in a mouse model of breast cancer. We used phage-assisted continuous evolution (PACE), which uncovered mutations at Arg12 that contact the DNA phosphodiester backbone. The Arg12 mutations improved ME47's stability. We replaced Cys29 with Ala to eliminate potential undesired disulfide formation and fused the designed FosW leucine zipper to mutated ME47 to increase the dimerization interface and E-box targeting activity. This "franken-protein" MEF comprises the Max basic region, E47 HLH, and FosW leucine zipper. Compared with ME47, MEF gives 2-fold stronger binding to E-box and 4-fold increased specificity for E-box over nonspecific DNA. The synergistic combination of rational design and PACE allowed us to make MEF and demonstrates the power and utility of our two-pronged approach toward development of promising protein drugs with robust structure and DNA-binding function.
Collapse
Affiliation(s)
- Ichiro Inamoto
- Department of Chemistry, University of Toronto, 3359 Mississauga Road, Mississauga, ON L5L 1C6, Canada
| | - Inder Sheoran
- Department of Chemistry, University of Toronto, 3359 Mississauga Road, Mississauga, ON L5L 1C6, Canada
| | - Serban C. Popa
- Department of Chemistry, University of Toronto, 3359 Mississauga Road, Mississauga, ON L5L 1C6, Canada
| | - Montdher Hussain
- Department of Chemistry, University of Toronto, 3359 Mississauga Road, Mississauga, ON L5L 1C6, Canada
| | - Jumi A. Shin
- Department of Chemistry, University of Toronto, 3359 Mississauga Road, Mississauga, ON L5L 1C6, Canada
| |
Collapse
|
3
|
Beaulieu ME, Castillo F, Soucek L. Structural and Biophysical Insights into the Function of the Intrinsically Disordered Myc Oncoprotein. Cells 2020; 9:E1038. [PMID: 32331235 PMCID: PMC7226237 DOI: 10.3390/cells9041038] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 04/16/2020] [Accepted: 04/17/2020] [Indexed: 12/13/2022] Open
Abstract
Myc is a transcription factor driving growth and proliferation of cells and involved in the majority of human tumors. Despite a huge body of literature on this critical oncogene, our understanding of the exact molecular determinants and mechanisms that underlie its function is still surprisingly limited. Indubitably though, its crucial and non-redundant role in cancer biology makes it an attractive target. However, achieving successful clinical Myc inhibition has proven challenging so far, as this nuclear protein is an intrinsically disordered polypeptide devoid of any classical ligand binding pockets. Indeed, Myc only adopts a (partially) folded structure in some contexts and upon interacting with some protein partners, for instance when dimerizing with MAX to bind DNA. Here, we review the cumulative knowledge on Myc structure and biophysics and discuss the implications for its biological function and the development of improved Myc inhibitors. We focus this biophysical walkthrough mainly on the basic region helix-loop-helix leucine zipper motif (bHLHLZ), as it has been the principal target for inhibitory approaches so far.
Collapse
Affiliation(s)
| | | | - Laura Soucek
- Peptomyc S.L., Edifici Cellex, 08035 Barcelona, Spain; (F.C.); (L.S.)
- Vall d’Hebron Institute of Oncology (VHIO), Edifici Cellex, 08035 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08035 Barcelona, Spain
- Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, 08035 Bellaterra, Spain
| |
Collapse
|
4
|
Popa SC, Shin JA. The Intrinsically Disordered Loop in the USF1 bHLHZ Domain Modulates Its DNA-Binding Sequence Specificity in Hereditary Asthma. J Phys Chem B 2019; 123:9862-9871. [PMID: 31670516 DOI: 10.1021/acs.jpcb.9b06719] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
USF1, a basic region/helix-loop-helix/leucine zipper (bHLHZ) transcription factor, binds to the E-box in the PAI-1 (plasminogen activator inhibitor) promoter. Two alleles containing the E-box control PAI-1 transcription; these alleles are termed "4G" and "5G" based on the G tract flanking E-box. USF1-governed transcription of PAI-1 is elevated in heritable asthma sufferers: the 4G/4G genotype has the highest plasma levels of PAI-1. While USF1 uses its basic region to bind E-box, we found that it uses its 12 amino-acid loop to recognize the flanking sequence and discern the single-nucleotide difference between the alleles. We used the bacterial one-hybrid and electrophoretic mobility shift assays to assess protein-DNA recognition, and circular dichroism to examine protein secondary structure. We mutated Ser233 and Thr234 in the USF1 bHLHZ loop to Ala to generate S233A and T234A. Interestingly, USF1 bHLHZ, S233A, and T234A prefer the 5G sequence (USF1 bHLHZ Kd values 4.1 ± 0.3 nM and 7.0 ± 0.4 nM for 5G and 4G, respectively), whereas studies in stimulated human mast cells showed a preference for 4G. We replaced the 8 amino-acid loop of transcription factor Max bHLHZ with the 12 amino-acid USF1 loop: this mutant now distinguishes the 4G/5G polymorphism-while Max bHLHZ does not-confirming that USF1 differentiation of the 4G/5G is driven by the loop.
Collapse
Affiliation(s)
- Serban C Popa
- Department of Chemistry , University of Toronto , 3359 Mississauga Road , Mississauga , Ontario L5L 1C6 , Canada
| | - Jumi A Shin
- Department of Chemistry , University of Toronto , 3359 Mississauga Road , Mississauga , Ontario L5L 1C6 , Canada
| |
Collapse
|
5
|
Tian S, Li L, Wei M, Yang F. Genome-wide analysis of basic helix-loop-helix superfamily members related to anthocyanin biosynthesis in eggplant ( Solanum melongena L.). PeerJ 2019; 7:e7768. [PMID: 31616588 PMCID: PMC6790105 DOI: 10.7717/peerj.7768] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 08/27/2019] [Indexed: 01/03/2023] Open
Abstract
The basic helix–loop–helix (bHLH) superfamily is considered the second largest transcription factor (TF) family. It plays regulatory roles in the developmental processes of plants and in their defense responses. In recent years, many bHLH superfamily genes have been identified and characterized in herbaceous and woody plants. However, the comprehensive genomic and functional analyses of these genes in eggplant (Solanum melongena L.) have not been reported. In this study, 121 bHLH TFs were identified in the recently released eggplant genome. The phylogeny, gene structure and conserved motifs of the SmbHLH gene were comprehensively studied. Subsequently, the phylogenetic relationship between the bHLH of eggplant and the bHLH of other species was analyzed, and the proteins were classified into 17 subfamilies. Among these protein sequences, 16 subgroups were clustered into the functional clades of Arabidopsis. Two candidate genes (SmbHLH1, SmbHLH117) that may be involved in anthocyanin biosynthesis were screened. The tissue specificity or differential expression of the bHLH genes in different tissues and under various light and temperature conditions suggested the differential regulation of tissue development and metabolism. This study not only provides a solid foundation for the functional dissection of the eggplant bHLH gene family but may also be useful for the future synthesis of anthocyanins in eggplant.
Collapse
Affiliation(s)
- Shiyu Tian
- College of Horticulture Science and Engineering, Shandong Agricultural University/ State Key Laboratory of Crop Biology, Taian, China
| | - Lujun Li
- College of Horticulture Science and Engineering, Shandong Agricultural University/ State Key Laboratory of Crop Biology, Taian, China
| | - Min Wei
- College of Horticulture Science and Engineering, Shandong Agricultural University/ State Key Laboratory of Crop Biology, Taian, China.,Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, Shandong Agricultural University, Taian, China
| | - Fengjuan Yang
- College of Horticulture Science and Engineering, Shandong Agricultural University/ State Key Laboratory of Crop Biology, Taian, China.,Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, Shandong Agricultural University, Taian, China.,Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Huanghuai Region), Ministry of Agriculture, Taian, China
| |
Collapse
|
6
|
Macek P, Cliff MJ, Embrey KJ, Holdgate GA, Nissink JWM, Panova S, Waltho JP, Davies RA. Myc phosphorylation in its basic helix-loop-helix region destabilizes transient α-helical structures, disrupting Max and DNA binding. J Biol Chem 2018; 293:9301-9310. [PMID: 29695509 DOI: 10.1074/jbc.ra118.002709] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 04/16/2018] [Indexed: 01/01/2023] Open
Abstract
Myelocytomatosis proto-oncogene transcription factor (Myc) is an intrinsically disordered protein with critical roles in cellular homeostasis and neoplastic transformation. It is tightly regulated in the cell, with Myc phosphorylation playing a major role. In addition to the well-described tandem phosphorylation of Thr-52 and Ser-62 in the Myc transactivation domain linked to its degradation, P21 (RAC1)-activated kinase 2 (PAK2)-mediated phosphorylation of serine and threonine residues in the C-terminal basic helix-loop-helix leucine zipper (bHLH-LZ) region regulates Myc transcriptional activity. Here we report that PAK2 preferentially phosphorylates Myc twice, at Thr-358 and Ser-373, with only a minor fraction being modified at the previously identified Thr-400 site. For transcriptional activity, Myc binds E-box DNA elements, requiring its heterodimerization with Myc-associated factor X (Max) via the bHLH-LZ regions. Using isothermal calorimetry (ITC), we found that Myc phosphorylation destabilizes this ternary protein-DNA complex by decreasing Myc's affinity for Max by 2 orders of magnitude, suggesting a major effect of phosphorylation on this complex. Phosphomimetic substitutions revealed that Ser-373 dominates the effect on Myc-Max heterodimerization. Moreover, a T400D substitution disrupted Myc's affinity for Max. ITC, NMR, and CD analyses of several Myc variants suggested that the effect of phosphorylation on the Myc-Max interaction is caused by secondary structure disruption during heterodimerization rather than by a change in the structurally disordered state of Myc or by phosphorylation-induced electrostatic repulsion in the heterodimer. Our findings provide critical insights into the effects of PAK2-catalyzed phosphorylation of Myc on its interactions with Max and DNA.
Collapse
Affiliation(s)
- Pavel Macek
- From AstraZeneca, IMED Discovery Sciences, Alderley Park SK10 4TG, United Kingdom,
| | - Matthew J Cliff
- the Manchester Institute of Biotechnology and School of Chemistry, University of Manchester, Manchester M1 7DN, United Kingdom
| | - Kevin J Embrey
- AstraZeneca, IMED Discovery Sciences, Cambridge CB4 0WG, United Kingdom
| | | | | | - Stanislava Panova
- the Manchester Institute of Biotechnology and School of Chemistry, University of Manchester, Manchester M1 7DN, United Kingdom
| | - Jonathan P Waltho
- the Manchester Institute of Biotechnology and School of Chemistry, University of Manchester, Manchester M1 7DN, United Kingdom
| | - Rick A Davies
- From AstraZeneca, IMED Discovery Sciences, Alderley Park SK10 4TG, United Kingdom,
| |
Collapse
|
7
|
Wang R, Zhao P, Kong N, Lu R, Pei Y, Huang C, Ma H, Chen Q. Genome-Wide Identification and Characterization of the Potato bHLH Transcription Factor Family. Genes (Basel) 2018; 9:genes9010054. [PMID: 29361801 PMCID: PMC5793205 DOI: 10.3390/genes9010054] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 01/09/2018] [Accepted: 01/18/2018] [Indexed: 11/24/2022] Open
Abstract
Plant basic/helix–loop–helix (bHLH) transcription factors participate in a number of biological processes, such as growth, development and abiotic stress responses. The bHLH family has been identified in many plants, and several bHLH transcription factors have been functionally characterized in Arabidopsis. However, no systematic identification of bHLH family members has been reported in potato (Solanum tuberosum). Here, 124 StbHLH genes were identified and named according to their chromosomal locations. The intron numbers varied from zero to seven. Most StbHLH proteins had the highly conserved intron phase 0, which accounted for 86.2% of the introns. According to the Neighbor-joining phylogenetic tree, 259 bHLH proteins acquired from Arabidopsis and potato were divided into 15 groups. All of the StbHLH genes were randomly distributed on 12 chromosomes, and 20 tandem duplicated genes and four pairs of duplicated gene segments were detected in the StbHLH family. The gene ontology (GO) analysis revealed that StbHLH mainly function in protein and DNA binding. Through the RNA-seq and quantitative real time PCR (qRT-PCR) analyses, StbHLH were found to be expressed in various tissues and to respond to abiotic stresses, including salt, drought and heat. StbHLH1, 41 and 60 were highly expressed in flower tissues, and were predicted to be involved in flower development by GO annotation. StbHLH45 was highly expressed in salt, drought and heat stress, which suggested its important role in abiotic stress response. The results provide comprehensive information for further analyses of the molecular functions of the StbHLH gene family.
Collapse
Affiliation(s)
- Ruoqiu Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Peng Zhao
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Nana Kong
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Ruize Lu
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Yue Pei
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Chenxi Huang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Haoli Ma
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Qin Chen
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
| |
Collapse
|
8
|
Maltais L, Montagne M, Bédard M, Tremblay C, Soucek L, Lavigne P. Biophysical characterization of the b-HLH-LZ of ΔMax, an alternatively spliced isoform of Max found in tumor cells: Towards the validation of a tumor suppressor role for the Max homodimers. PLoS One 2017; 12:e0174413. [PMID: 28350847 PMCID: PMC5370111 DOI: 10.1371/journal.pone.0174413] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 03/08/2017] [Indexed: 11/19/2022] Open
Abstract
It is classically recognized that the physiological and oncogenic functions of Myc proteins depend on specific DNA binding enabled by the dimerization of its C-terminal basic-region-Helix-Loop-Helix-Leucine Zipper (b-HLH-LZ) domain with that of Max. However, a new paradigm is emerging, where the binding of the c-Myc/Max heterodimer to non-specific sequences in enhancers and promoters drives the transcription of genes involved in diverse oncogenic programs. Importantly, Max can form a stable homodimer even in the presence of c-Myc and bind DNA (specific and non-specific) with comparable affinity to the c-Myc/Max heterodimer. Intriguingly, alterations in the Max gene by germline and somatic mutations or changes in the gene product by alternative splicing (e.g. ΔMax) were recently associated with pheochromocytoma and glioblastoma, respectively. This has led to the proposition that Max is, by itself, a tumor suppressor. However, the actual mechanism through which it exerts such an activity remains to be elucidated. Here, we show that contrary to the WT motif, the b-HLH-LZ of ΔMax does not homodimerize in the absence of DNA. In addition, although ΔMax can still bind the E-box sequence as a homodimer, it cannot bind non-specific DNA in that form, while it can heterodimerize with c-Myc and bind E-box and non-specific DNA as a heterodimer with high affinity. Taken together, our results suggest that the WT Max homodimer is important for attenuating the binding of c-Myc to specific and non-specific DNA, whereas ΔMax is unable to do so. Conversely, the splicing of Max into ΔMax could provoke an increase in overall chromatin bound c-Myc. According to the new emerging paradigm, the splicing event and the stark reduction in homodimer stability and DNA binding should promote tumorigenesis impairing the tumor suppressor activity of the WT homodimer of Max.
Collapse
Affiliation(s)
- Loïka Maltais
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
- PROTÉO; Regroupement Stratégique sur la Fonction, la Structure et l'Ingénierie des Protéines, Université Laval, Québec, Canada
| | - Martin Montagne
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
- PROTÉO; Regroupement Stratégique sur la Fonction, la Structure et l'Ingénierie des Protéines, Université Laval, Québec, Canada
| | - Mikaël Bédard
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
- PROTÉO; Regroupement Stratégique sur la Fonction, la Structure et l'Ingénierie des Protéines, Université Laval, Québec, Canada
| | - Cynthia Tremblay
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
- PROTÉO; Regroupement Stratégique sur la Fonction, la Structure et l'Ingénierie des Protéines, Université Laval, Québec, Canada
| | - Laura Soucek
- Vall d’Hebron Institute of Oncology (VHIO), Hospital Vall d’Hebron, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
- Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Pierre Lavigne
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
- PROTÉO; Regroupement Stratégique sur la Fonction, la Structure et l'Ingénierie des Protéines, Université Laval, Québec, Canada
- * E-mail:
| |
Collapse
|
9
|
Beaulieu ME, McDuff FO, Frappier V, Montagne M, Naud JF, Lavigne P. New structural determinants for c-Myc specific heterodimerization with Max and development of a novel homodimeric c-Myc b-HLH-LZ. J Mol Recognit 2012; 25:414-26. [PMID: 22733550 DOI: 10.1002/jmr.2203] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
c-Myc must heterodimerize with Max to accomplish its functions as a transcription factor. This specific heterodimerization occurs through the b-HLH-LZ (basic region, helix 1-loop-helix 2-leucine zipper) domains. In fact, many studies have shown that the c-Myc b-HLH-LZ (c-Myc'SH) preferentially forms a heterodimer with the Max b-HLH-LZ (Max'SH). The primary mechanism underlying the specific heterodimerization lies on the destabilization of both homodimers and the formation of a more stable heterodimer. In this regard, it has been widely reported that c-Myc'SH has low solubility and homodimerizes poorly and that repulsions within the LZ domain account for the homodimer instability. Here, we show that replacing one residue in the basic region and one residue in Helix 1 (H(1)) of c-Myc'SH with corresponding residues conserved in b-HLH proteins confers to c-Myc'SH a higher propensity to form a stable homodimer in solution. In stark contrast to the wild-type protein, this double mutant (L362R, R367L) of the c-Myc b-HLH-LZ (c-Myc'RL) shows limited heterodimerization with Max'SH in vitro. In addition, c-Myc'RL forms highly stable and soluble complexes with canonical as well as non-canonical E-box probes. Altogether, our results demonstrate for the first time that structural determinants driving the specific heterodimerization of c-Myc and Max are embedded in the basic region and H(1) of c-Myc and that these can be exploited to engineer a novel homodimeric c-Myc b-HLH-LZ with the ability of binding the E-box sequence autonomously and with high affinity.
Collapse
Affiliation(s)
- Marie-Eve Beaulieu
- Département de Pharmacologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, 3001, 12e Avenue Nord, Sherbrooke, Québec, J1H 5N4, Canada
| | | | | | | | | | | |
Collapse
|
10
|
Chen G, De Jong AT, Shin JA. Forced homodimerization of the c-Fos leucine zipper in designed bHLHZ-like hybrid proteins MaxbHLH-Fos and ArntbHLH-Fos. MOLECULAR BIOSYSTEMS 2012; 8:1286-96. [DOI: 10.1039/c2mb05354c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
11
|
Ecevit O, Khan MA, Goss DJ. Kinetic analysis of the interaction of b/HLH/Z transcription factors Myc, Max, and Mad with cognate DNA. Biochemistry 2010; 49:2627-35. [PMID: 20170194 PMCID: PMC2852888 DOI: 10.1021/bi901913a] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Myc, Mad, and Max proteins belong to the basic helix-loop-helix leucine zipper family of transcription factors. They bind to a specific hexanucleotide element of DNA, the E-box (CACGTG). To be biologically active, Myc and Mad require dimerization with Max. For the route of complex assembly of these dimers, there are two proposed pathways. In the monomer pathway, two monomers bind DNA sequentially and assemble their dimerization interface while bound to DNA. In the dimer pathway, two monomers form a dimer first prior to association with DNA. The monomer pathway is kinetically favored. In this report, stopped-flow polarization was utilized to determine the rates and temperature dependence of all of the individual steps for both assembly pathways. Myc.Max dimerization had a rate constant approximately 5- and approximately 2-fold higher than those of Max.Max and Mad.Max dimerization, respectively. The protein dimerization rates as well as the dimer-DNA rates were found to be independent of concentration, suggesting conformational changes were rate-limiting. The Arrhenius activation energies for the dimerization of Myc, Mad, and Max with Max were 20.4 +/- 0.8, 29 +/- 0.6, and 40 +/- 0.2 kJ/mol, respectively. Further, rate constants for Max.Max homodimer DNA binding are significantly higher than for Myc.Max and Mad.Max heterodimers binding to DNA. Monomer-DNA binding showed a faster rate than dimer-DNA binding. These studies show the rate-limiting step for the dimer pathway is the formation of protein dimers, and this reaction is slower than formation of protein dimers on the DNA interface, kinetically favoring the monomer pathway.
Collapse
Affiliation(s)
- Ozgur Ecevit
- Department of Chemistry and Biochemistry, Hunter College and Graduate Center of the City University of New York, New York, NY 10065
| | - Mateen A Khan
- Department of Chemistry and Biochemistry, Hunter College and Graduate Center of the City University of New York, New York, NY 10065
| | - Dixie J Goss
- Department of Chemistry and Biochemistry, Hunter College and Graduate Center of the City University of New York, New York, NY 10065
| |
Collapse
|
12
|
Aguado-Llera D, Goormaghtigh E, de Geest N, Quan XJ, Prieto A, Hassan BA, Gómez J, Neira JL. The basic helix-loop-helix region of human neurogenin 1 is a monomeric natively unfolded protein which forms a "fuzzy" complex upon DNA binding. Biochemistry 2010; 49:1577-89. [PMID: 20102160 DOI: 10.1021/bi901616z] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Neuronal specification is regulated by the activity of transcription factors containing the basic helix-loop-helix motif (bHLH); these regulating proteins include, among others, the neurogenin (Ngn) family, related to the atonal family of genes. Neurogenin 1 (NGN1) is a 237-residue protein that contains a bHLH domain and is involved in neuronal differentiation. In this work, we synthesized the bHLH region of NGN1 (bHLHN) comprising residues 90-150 of the full-length NGN1. The domain is a monomeric natively unfolded protein with a pH-dependent premolten globule conformation, as shown by several spectroscopic techniques (namely, NMR, fluorescence, FTIR, and circular dichroism). The unfolded character of the domain also explains, first, the impossibility of its overexpression in several Escherichia coli strains and, second, its insolubility in aqueous buffers. To the best of our knowledge, this is the first extensive study of the conformational preferences of a bHLH domain under different solution conditions. Upon binding to two DNA E-boxes, the protein forms "fuzzy" complexes (that is, the complexes were not fully folded). The affinities of bHLHN for both DNA boxes were smaller than those of other bHLH domains, which might explain why the protein-DNA complexes were not fully folded.
Collapse
Affiliation(s)
- David Aguado-Llera
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, 03202 Elche (Alicante), Spain
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Xu J, De Jong AT, Chen G, Chow HK, Damaso CO, Schwartz Mittelman A, Shin JA. Reengineering natural design by rational design and in vivo library selection: the HLH subdomain in bHLHZ proteins is a unique requirement for DNA-binding function. Protein Eng Des Sel 2010; 23:337-46. [PMID: 20086039 DOI: 10.1093/protein/gzp082] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
To explore the role of the HLH subdomain in bHLHZ proteins, we designed sets of minimalist proteins based on bHLHZ protein Max, bHLH/PAS protein Arnt and bZIP protein C/EBP. In the first, the Max bHLH and C/EBP leucine zipper were fused such that the leucine heptad repeats were not in register; therefore, the protein dimerization interface was disrupted. Max1bHLH-C/EBP showed little ability to activate transcription from the E-box (5'-CACGTG) in the yeast one-hybrid assay, and no E-box binding by quantitative fluorescence anisotropy. Max1bHLH-C/EBP's activity was significantly improved after library selection (three amino acids randomized between HLH and leucine zipper), despite the Max bHLH and C/EBP zipper still being out of register: a representative mutant gave a high nanomolar K(d) value for E-box binding. Thus, selection proved to be a powerful tool for salvaging the flawed Max1bHLH-C/EBP, although the out-of-register mutants still did not achieve the strong DNA-binding affinities displayed by their in-register counterparts. ArntbHLH-C/EBP hybrids further demonstrated the importance of maintaining register, as out-of-register mutants showed no E-box-responsive activity, whereas the in-register hybrid showed moderate activity. In another design, we eliminated the HLH altogether and fused the Max basic region to the C/EBP zipper to generate bZIP-like hybrids. Despite numerous designs and selections, these hybrids possessed no E-box-responsive activity. Finally, we tested the importance of the loop sequence in MaxbHLHZ by fluorescence and circular dichroism. In one mutant, the loop was shortened by two residues; in the other, the Lys57:DNA-backbone interaction was abolished by mutation to Gly57. Both showed markedly decreased E-box-binding relative to MaxbHLHZ. Our results suggest that, in contrast to the more rigid bZIP, the HLH is capable of significant conformational adaptation to enable gene-regulatory function and is required for protein dimerization and positioning the basic region for DNA recognition.
Collapse
Affiliation(s)
- Jing Xu
- Department of Chemistry, University of Toronto, Mississauga, ON L5L1C6, Canada
| | | | | | | | | | | | | |
Collapse
|
14
|
Roselin LS, Lin MS, Lin PH, Chang Y, Chen WY. Recent trends and some applications of isothermal titration calorimetry in biotechnology. Biotechnol J 2010; 5:85-98. [DOI: 10.1002/biot.200900092] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
15
|
Xu J, Chen G, De Jong AT, Shahravan SH, Shin JA. Max-E47, a designed minimalist protein that targets the E-box DNA site in vivo and in vitro. J Am Chem Soc 2009; 131:7839-48. [PMID: 19449889 PMCID: PMC2734406 DOI: 10.1021/ja901306q] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Max-E47 is a designed hybrid protein comprising the Max DNA-binding basic region and E47 HLH dimerization subdomain. In the yeast one-hybrid system (Y1H), Max-E47 shows strong transcriptional activation from the E-box site, 5'-CACGTG, targeted by the Myc/Max/Mad network of transcription factors; two mutants, Max-E47Y and Max-E47YF, activate more weakly from the E-box in the Y1H. Quantitative fluorescence anisotropy titrations to gain free energies of protein:DNA binding gave low nanomolar K(d) values for the native MaxbHLHZ, Max-E47, and the Y and YF mutants binding to the E-box site (14, 15, 9, and 6 nM, respectively), with no detectable binding to a nonspecific control duplex. Because these minimalist, E-box-binding hybrids have no activation domain and no interactions with the c-MycbHLHZ, as shown by the yeast two-hybrid assay, they can potentially serve as dominant-negative inhibitors that suppress activation of E-box-responsive genes targeted by transcription factors including the c-Myc/Max complex. As proof-of-principle, we used our modified Y1H, which allows direct competition between two proteins vying for a DNA target, to show that Max-E47 effectively outcompetes the native MaxbHLHZ for the E-box; weaker competition is observed from the two mutants, consistent with Y1H results. These hybrids provide a minimalist scaffold for further exploration of the relationship between protein structure and DNA-binding function and may have applications as protein therapeutics or biochemical probes capable of targeting the E-box site.
Collapse
Affiliation(s)
- Jing Xu
- Department of Chemistry, University of Toronto, Mississauga, Ontario L5L 1C6, Canada
| | | | | | | | | |
Collapse
|
16
|
Bjelić S, Jelesarov I. A survey of the year 2007 literature on applications of isothermal titration calorimetry. J Mol Recognit 2008; 21:289-312. [PMID: 18729242 DOI: 10.1002/jmr.909] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Elucidation of the energetic principles of binding affinity and specificity is a central task in many branches of current sciences: biology, medicine, pharmacology, chemistry, material sciences, etc. In biomedical research, integral approaches combining structural information with in-solution biophysical data have proved to be a powerful way toward understanding the physical basis of vital cellular phenomena. Isothermal titration calorimetry (ITC) is a valuable experimental tool facilitating quantification of the thermodynamic parameters that characterize recognition processes involving biomacromolecules. The method provides access to all relevant thermodynamic information by performing a few experiments. In particular, ITC experiments allow to by-pass tedious and (rarely precise) procedures aimed at determining the changes in enthalpy and entropy upon binding by van't Hoff analysis. Notwithstanding limitations, ITC has now the reputation of being the "gold standard" and ITC data are widely used to validate theoretical predictions of thermodynamic parameters, as well as to benchmark the results of novel binding assays. In this paper, we discuss several publications from 2007 reporting ITC results. The focus is on applications in biologically oriented fields. We do not intend a comprehensive coverage of all newly accumulated information. Rather, we emphasize work which has captured our attention with originality and far-reaching analysis, or else has provided ideas for expanding the potential of the method.
Collapse
Affiliation(s)
- Sasa Bjelić
- Biochemisches Institut der Universität Zürich, Winterthurerstrasse 190, Zürich, Switzerland
| | | |
Collapse
|
17
|
Chow HK, Xu J, Shahravan SH, De Jong AT, Chen G, Shin JA. Hybrids of the bHLH and bZIP protein motifs display different DNA-binding activities in vivo vs. in vitro. PLoS One 2008; 3:e3514. [PMID: 18949049 PMCID: PMC2568859 DOI: 10.1371/journal.pone.0003514] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2008] [Accepted: 10/02/2008] [Indexed: 12/18/2022] Open
Abstract
Minimalist hybrids comprising the DNA-binding domain of bHLH/PAS (basic-helix-loop-helix/Per-Arnt-Sim) protein Arnt fused to the leucine zipper (LZ) dimerization domain from bZIP (basic region-leucine zipper) protein C/EBP were designed to bind the E-box DNA site, CACGTG, targeted by bHLHZ (basic-helix-loop-helix-zipper) proteins Myc and Max, as well as the Arnt homodimer. The bHLHZ-like structure of ArntbHLH-C/EBP comprises the Arnt bHLH domain fused to the C/EBP LZ: i.e. swap of the 330 aa PAS domain for the 29 aa LZ. In the yeast one-hybrid assay (Y1H), transcriptional activation from the E-box was strong by ArntbHLH-C/EBP, and undetectable for the truncated ArntbHLH (PAS removed), as detected via readout from the HIS3 and lacZ reporters. In contrast, fluorescence anisotropy titrations showed affinities for the E-box with ArntbHLH-C/EBP and ArntbHLH comparable to other transcription factors (K(d) 148.9 nM and 40.2 nM, respectively), but only under select conditions that maintained folded protein. Although in vivo yeast results and in vitro spectroscopic studies for ArntbHLH-C/EBP targeting the E-box correlate well, the same does not hold for ArntbHLH. As circular dichroism confirms that ArntbHLH-C/EBP is a much more strongly alpha-helical structure than ArntbHLH, we conclude that the nonfunctional ArntbHLH in the Y1H must be due to misfolding, leading to the false negative that this protein is incapable of targeting the E-box. Many experiments, including protein design and selections from large libraries, depend on protein domains remaining well-behaved in the nonnative experimental environment, especially small motifs like the bHLH (60-70 aa). Interestingly, a short helical LZ can serve as a folding- and/or solubility-enhancing tag, an important device given the focus of current research on exploration of vast networks of biomolecular interactions.
Collapse
Affiliation(s)
- Hiu-Kwan Chow
- Department of Chemistry, University of Toronto, Mississauga, Ontario, Canada
| | - Jing Xu
- Department of Chemistry, University of Toronto, Mississauga, Ontario, Canada
| | - S. Hesam Shahravan
- Department of Chemistry, University of Toronto, Mississauga, Ontario, Canada
| | - Antonia T. De Jong
- Department of Chemistry, University of Toronto, Mississauga, Ontario, Canada
| | - Gang Chen
- Department of Chemistry, University of Toronto, Mississauga, Ontario, Canada
| | - Jumi A. Shin
- Department of Chemistry, University of Toronto, Mississauga, Ontario, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|