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Wu K, Dhillon N, Bajor A, Abrahamsson S, Kamakaka RT. Yeast heterochromatin stably silences only weak regulatory elements by altering burst duration. Cell Rep 2024; 43:113983. [PMID: 38517895 PMCID: PMC11141299 DOI: 10.1016/j.celrep.2024.113983] [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: 08/24/2023] [Revised: 12/25/2023] [Accepted: 03/06/2024] [Indexed: 03/24/2024] Open
Abstract
Transcriptional silencing in Saccharomyces cerevisiae involves the generation of a chromatin state that stably represses transcription. Using multiple reporter assays, a diverse set of upstream activating sequence enhancers and core promoters were investigated for their susceptibility to silencing. We show that heterochromatin stably silences only weak and stress-induced regulatory elements but is unable to stably repress housekeeping gene regulatory elements, and the partial repression of these elements did not result in bistable expression states. Permutation analysis of enhancers and promoters indicates that both elements are targets of repression. Chromatin remodelers help specific regulatory elements to resist repression, most probably by altering nucleosome mobility and changing transcription burst duration. The strong enhancers/promoters can be repressed if silencer-bound Sir1 is increased. Together, our data suggest that the heterochromatic locus has been optimized to stably silence the weak mating-type gene regulatory elements but not strong housekeeping gene regulatory sequences.
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Affiliation(s)
- Kenneth Wu
- Department of MCD Biology, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Namrita Dhillon
- Department of MCD Biology, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Antone Bajor
- Electrical Engineering Department, Baskin School of Engineering, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Sara Abrahamsson
- Electrical Engineering Department, Baskin School of Engineering, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Rohinton T Kamakaka
- Department of MCD Biology, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA.
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2
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Cautereels C, Smets J, Bircham P, De Ruysscher D, Zimmermann A, De Rijk P, Steensels J, Gorkovskiy A, Masschelein J, Verstrepen KJ. Combinatorial optimization of gene expression through recombinase-mediated promoter and terminator shuffling in yeast. Nat Commun 2024; 15:1112. [PMID: 38326309 PMCID: PMC10850122 DOI: 10.1038/s41467-024-44997-7] [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: 08/10/2023] [Accepted: 01/12/2024] [Indexed: 02/09/2024] Open
Abstract
Microbes are increasingly employed as cell factories to produce biomolecules. This often involves the expression of complex heterologous biosynthesis pathways in host strains. Achieving maximal product yields and avoiding build-up of (toxic) intermediates requires balanced expression of every pathway gene. However, despite progress in metabolic modeling, the optimization of gene expression still heavily relies on trial-and-error. Here, we report an approach for in vivo, multiplexed Gene Expression Modification by LoxPsym-Cre Recombination (GEMbLeR). GEMbLeR exploits orthogonal LoxPsym sites to independently shuffle promoter and terminator modules at distinct genomic loci. This approach facilitates creation of large strain libraries, in which expression of every pathway gene ranges over 120-fold and each strain harbors a unique expression profile. When applied to the biosynthetic pathway of astaxanthin, an industrially relevant antioxidant, a single round of GEMbLeR improved pathway flux and doubled production titers. Together, this shows that GEMbLeR allows rapid and efficient gene expression optimization in heterologous biosynthetic pathways, offering possibilities for enhancing the performance of microbial cell factories.
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Affiliation(s)
- Charlotte Cautereels
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium
- Laboratory of Genetics and Genomics, Center of Microbial and Plant Genetics, Department M2S, KU Leuven, Gaston Geenslaan 1, Leuven, 3001, Belgium
| | - Jolien Smets
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium
- Laboratory of Genetics and Genomics, Center of Microbial and Plant Genetics, Department M2S, KU Leuven, Gaston Geenslaan 1, Leuven, 3001, Belgium
| | - Peter Bircham
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium
- Laboratory of Genetics and Genomics, Center of Microbial and Plant Genetics, Department M2S, KU Leuven, Gaston Geenslaan 1, Leuven, 3001, Belgium
| | - Dries De Ruysscher
- Molecular Biotechnology of Plants and Micro-organisms, Department of Biology, KU Leuven, Kasteelpark Arenberg 31, box 2438, Leuven, 3001, Belgium
- Laboratory for Biomolecular Discovery & Engineering, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium
| | - Anna Zimmermann
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium
- Laboratory of Genetics and Genomics, Center of Microbial and Plant Genetics, Department M2S, KU Leuven, Gaston Geenslaan 1, Leuven, 3001, Belgium
| | - Peter De Rijk
- Neuromics Support Facility, VIB Center for Molecular Neurology, VIB, Antwerp, 2610, Belgium
- Neuromics Support Facility, Department of Biomedical Sciences, University of Antwerp, Antwerp, 2610, Belgium
| | - Jan Steensels
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium
- Laboratory of Genetics and Genomics, Center of Microbial and Plant Genetics, Department M2S, KU Leuven, Gaston Geenslaan 1, Leuven, 3001, Belgium
| | - Anton Gorkovskiy
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium
- Laboratory of Genetics and Genomics, Center of Microbial and Plant Genetics, Department M2S, KU Leuven, Gaston Geenslaan 1, Leuven, 3001, Belgium
| | - Joleen Masschelein
- Molecular Biotechnology of Plants and Micro-organisms, Department of Biology, KU Leuven, Kasteelpark Arenberg 31, box 2438, Leuven, 3001, Belgium
- Laboratory for Biomolecular Discovery & Engineering, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium
| | - Kevin J Verstrepen
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium.
- Laboratory of Genetics and Genomics, Center of Microbial and Plant Genetics, Department M2S, KU Leuven, Gaston Geenslaan 1, Leuven, 3001, Belgium.
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Zhu Y, Vvedenskaya IO, Sze SH, Nickels BE, Kaplan CD. Quantitative analysis of transcription start site selection reveals control by DNA sequence, RNA polymerase II activity and NTP levels. Nat Struct Mol Biol 2024; 31:190-202. [PMID: 38177677 PMCID: PMC10928753 DOI: 10.1038/s41594-023-01171-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 11/03/2023] [Indexed: 01/06/2024]
Abstract
Transcription start site (TSS) selection is a key step in gene expression and occurs at many promoter positions over a wide range of efficiencies. Here we develop a massively parallel reporter assay to quantitatively dissect contributions of promoter sequence, nucleoside triphosphate substrate levels and RNA polymerase II (Pol II) activity to TSS selection by 'promoter scanning' in Saccharomyces cerevisiae (Pol II MAssively Systematic Transcript End Readout, 'Pol II MASTER'). Using Pol II MASTER, we measure the efficiency of Pol II initiation at 1,000,000 individual TSS sequences in a defined promoter context. Pol II MASTER confirms proposed critical qualities of S. cerevisiae TSS -8, -1 and +1 positions, quantitatively, in a controlled promoter context. Pol II MASTER extends quantitative analysis to surrounding sequences and determines that they tune initiation over a wide range of efficiencies. These results enabled the development of a predictive model for initiation efficiency based on sequence. We show that genetic perturbation of Pol II catalytic activity alters initiation efficiency mostly independently of TSS sequence, but selectively modulates preference for the initiating nucleotide. Intriguingly, we find that Pol II initiation efficiency is directly sensitive to guanosine-5'-triphosphate levels at the first five transcript positions and to cytosine-5'-triphosphate and uridine-5'-triphosphate levels at the second position genome wide. These results suggest individual nucleoside triphosphate levels can have transcript-specific effects on initiation, representing a cryptic layer of potential regulation at the level of Pol II biochemical properties. The results establish Pol II MASTER as a method for quantitative dissection of transcription initiation in eukaryotes.
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Affiliation(s)
- Yunye Zhu
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Irina O Vvedenskaya
- Department of Genetics and Waksman Institute, Rutgers University, Piscataway, NJ, USA
| | - Sing-Hoi Sze
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
- Department of Computer Science and Engineering, Texas A&M University, College Station, TX, USA
| | - Bryce E Nickels
- Department of Genetics and Waksman Institute, Rutgers University, Piscataway, NJ, USA
| | - Craig D Kaplan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA.
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Wu K, Dhillon N, Bajor A, Abrahamson S, Kamakaka RT. Yeast Heterochromatin Only Stably Silences Weak Regulatory Elements by Altering Burst Duration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.05.561072. [PMID: 37873261 PMCID: PMC10592971 DOI: 10.1101/2023.10.05.561072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
The interplay between nucleosomes and transcription factors leads to programs of gene expression. Transcriptional silencing involves the generation of a chromatin state that represses transcription and is faithfully propagated through DNA replication and cell division. Using multiple reporter assays, including directly visualizing transcription in single cells, we investigated a diverse set of UAS enhancers and core promoters for their susceptibility to heterochromatic gene silencing. These results show that heterochromatin only stably silences weak and stress induced regulatory elements but is unable to stably repress housekeeping gene regulatory elements and the partial repression did not result in bistable expression states. Permutation analysis of different UAS enhancers and core promoters indicate that both elements function together to determine the susceptibility of regulatory sequences to repression. Specific histone modifiers and chromatin remodellers function in an enhancer specific manner to aid these elements to resist repression suggesting that Sir proteins likely function in part by reducing nucleosome mobility. We also show that the strong housekeeping regulatory elements can be repressed if silencer bound Sir1 is increased, suggesting that Sir1 is a limiting component in silencing. Together, our data suggest that the heterochromatic locus has been optimized to stably silence the weak mating type gene regulatory elements but not strong housekeeping gene regulatory sequences which could help explain why these genes are often found at the boundaries of silenced domains.
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Affiliation(s)
- Kenneth Wu
- Department of MCD Biology, 1156 High Street, University of California, Santa Cruz, CA 95064 USA
| | - Namrita Dhillon
- Department of MCD Biology, 1156 High Street, University of California, Santa Cruz, CA 95064 USA
| | - Antone Bajor
- Electrical Engineering Department, Baskin School of Engineering, 1156 High Street, University of California, Santa Cruz, CA 95064 USA
| | - Sara Abrahamson
- Electrical Engineering Department, Baskin School of Engineering, 1156 High Street, University of California, Santa Cruz, CA 95064 USA
| | - Rohinton T. Kamakaka
- Department of MCD Biology, 1156 High Street, University of California, Santa Cruz, CA 95064 USA
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Zhou LY, Zhang S, Li LY, Yang GY, Zeng L. Optimization of mammalian expression vector by cis-regulatory element combinations. Mol Genet Genomics 2023:10.1007/s00438-023-02042-0. [PMID: 37318628 DOI: 10.1007/s00438-023-02042-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 05/31/2023] [Indexed: 06/16/2023]
Abstract
The regulation of gene expression in mammalian cells by combining various cis-regulatory features has rarely been discussed. In this study, we constructed expression vectors containing various combinations of regulatory elements to examine the regulation of gene expression by different combinations of cis-regulatory elements. The effects of four promoters (CMV promoter, PGK promoter, Polr2a promoter, and EF-1α core promoter), two enhancers (CMV enhancer and SV40 enhancer), two introns (EF-1α intron A and hybrid intron), two terminators (CYC1 terminator and TEF terminator), and their different combinations on downstream gene expression were compared in various mammalian cells using fluorescence microscopy to observe fluorescence, quantitative real-time PCR (qRT-PCR), and western blot. The receptor binding domain (RBD) sequence from severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike protein was used to replace the eGFP sequence in the expression vector and the RBD expression was detected by qRT-PCR and western blot. The results showed that protein expression can be regulated by optimizing the combination of cis-acting elements. The vector with the CMV enhancer, EF-1α core promoter, and TEF terminator was found to express approximately threefold higher eGFP than the unmodified vector in different animal cells, as well as 2.63-fold higher recombinant RBD protein than the original vector in HEK-293T cells. Moreover, we suggest that combinations of multiple regulatory elements capable of regulating gene expression do not necessarily exhibit synergistic effects to enhance expression further. Overall, our findings provide insights into biological applications that require the regulation of gene expression and will help to optimize expression vectors for biosynthesis and other fields. Additionally, we provide valuable insights into the production of RBD proteins, which may aid in developing reagents for diagnosis and treatment during the COVID-19 pandemic.
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Affiliation(s)
- Lu-Yu Zhou
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, Henan, People's Republic of China
- Key Laboratory of Animal Biochemistry and Nutrition, Henan Agricultural University, Ministry of Agriculture and Rural Affairs, Zhengzhou, 450046, Henan, People's Republic of China
- Key Laboratory of Animal Growth and Development, The Education Department of Henan Province, Zhengzhou, 450046, Henan, People's Republic of China
| | - Shuang Zhang
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, Henan, People's Republic of China
- Key Laboratory of Animal Biochemistry and Nutrition, Henan Agricultural University, Ministry of Agriculture and Rural Affairs, Zhengzhou, 450046, Henan, People's Republic of China
- Key Laboratory of Animal Growth and Development, The Education Department of Henan Province, Zhengzhou, 450046, Henan, People's Republic of China
| | - Li-Yun Li
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, Henan, People's Republic of China
- Key Laboratory of Animal Biochemistry and Nutrition, Henan Agricultural University, Ministry of Agriculture and Rural Affairs, Zhengzhou, 450046, Henan, People's Republic of China
- Key Laboratory of Animal Growth and Development, The Education Department of Henan Province, Zhengzhou, 450046, Henan, People's Republic of China
| | - Guo-Yu Yang
- Key Laboratory of Animal Biochemistry and Nutrition, Henan Agricultural University, Ministry of Agriculture and Rural Affairs, Zhengzhou, 450046, Henan, People's Republic of China
- Key Laboratory of Animal Growth and Development, The Education Department of Henan Province, Zhengzhou, 450046, Henan, People's Republic of China
| | - Lei Zeng
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, Henan, People's Republic of China.
- Key Laboratory of Animal Biochemistry and Nutrition, Henan Agricultural University, Ministry of Agriculture and Rural Affairs, Zhengzhou, 450046, Henan, People's Republic of China.
- Key Laboratory of Animal Growth and Development, The Education Department of Henan Province, Zhengzhou, 450046, Henan, People's Republic of China.
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6
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Evaluation of Aspergillus niger Six Constitutive Strong Promoters by Fluorescent-Auxotrophic Selection Coupled with Flow Cytometry: A Case for Citric Acid Production. J Fungi (Basel) 2022; 8:jof8060568. [PMID: 35736051 PMCID: PMC9224621 DOI: 10.3390/jof8060568] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 05/19/2022] [Accepted: 05/24/2022] [Indexed: 02/05/2023] Open
Abstract
Aspergillus niger is an important industrial workhorse for the biomanufacturing of organic acids, proteins, etc. Well-controlled genetic regulatory elements, including promoters, are vital for strain engineering, but available strong promoters for A. niger are limited. Herein, to efficiently assess promoters, we developed an accurate and intuitive fluorescent-auxotrophic selection workflow based on mCherry, pyrG, CRISPR/Cas9 system, and flow cytometry. With this workflow, we characterized six endogenous constitutive promoters in A. niger. The endogenous glyceraldehyde-3-phosphate dehydrogenase promoter PgpdAg showed a 2.28-fold increase in promoter activity compared with the most frequently used strong promoter PgpdAd from A. nidulans. Six predicted conserved motifs, including the gpdA-box, were verified to be essential for the PgpdAg activity. To demonstrate its application, the promoter PgpdAg was used for enhancing the expression of citrate exporter cexA in a citric acid-producing isolate D353.8. Compared with the cexA controlled by PgpdAd, the transcription level of the cexA gene driven by PgpdAg increased by 2.19-fold, which is consistent with the promoter activity assessment. Moreover, following cexA overexpression, several genes involved in carbohydrate transport and metabolism were synergically upregulated, resulting in up to a 2.48-fold increase in citric acid titer compared with that of the parent strain. This study provides an intuitive workflow to speed up the quantitative evaluation of A. niger promoters and strong constitutive promoters for fungal cell factory construction and strain engineering.
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Cazier AP, Blazeck J. Advances in promoter engineering: novel applications and predefined transcriptional control. Biotechnol J 2021; 16:e2100239. [PMID: 34351706 DOI: 10.1002/biot.202100239] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 07/30/2021] [Accepted: 08/03/2021] [Indexed: 11/08/2022]
Abstract
Synthetic biology continues to progress by relying on more robust tools for transcriptional control, of which promoters are the most fundamental component. Numerous studies have sought to characterize promoter function, determine principles to guide their engineering, and create promoters with stronger expression or tailored inducible control. In this review, we will summarize promoter architecture and highlight recent advances in the field, focusing on the novel applications of inducible promoter design and engineering towards metabolic engineering and cellular therapeutic development. Additionally, we will highlight how the expansion of new, machine learning techniques for modeling and engineering promoter sequences are enabling more accurate prediction of promoter characteristics. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Andrew P Cazier
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst St. NW, Atlanta, Georgia, 30332, USA
| | - John Blazeck
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst St. NW, Atlanta, Georgia, 30332, USA
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Zrimec J, Buric F, Kokina M, Garcia V, Zelezniak A. Learning the Regulatory Code of Gene Expression. Front Mol Biosci 2021; 8:673363. [PMID: 34179082 PMCID: PMC8223075 DOI: 10.3389/fmolb.2021.673363] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 05/24/2021] [Indexed: 11/13/2022] Open
Abstract
Data-driven machine learning is the method of choice for predicting molecular phenotypes from nucleotide sequence, modeling gene expression events including protein-DNA binding, chromatin states as well as mRNA and protein levels. Deep neural networks automatically learn informative sequence representations and interpreting them enables us to improve our understanding of the regulatory code governing gene expression. Here, we review the latest developments that apply shallow or deep learning to quantify molecular phenotypes and decode the cis-regulatory grammar from prokaryotic and eukaryotic sequencing data. Our approach is to build from the ground up, first focusing on the initiating protein-DNA interactions, then specific coding and non-coding regions, and finally on advances that combine multiple parts of the gene and mRNA regulatory structures, achieving unprecedented performance. We thus provide a quantitative view of gene expression regulation from nucleotide sequence, concluding with an information-centric overview of the central dogma of molecular biology.
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Affiliation(s)
- Jan Zrimec
- Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Filip Buric
- Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Mariia Kokina
- Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Victor Garcia
- School of Life Sciences and Facility Management, Zurich University of Applied Sciences, Wädenswil, Switzerland
| | - Aleksej Zelezniak
- Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
- Science for Life Laboratory, Stockholm, Sweden
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