1
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Chappleboim M, Naveh-Tassa S, Carmi M, Levy Y, Barkai N. Ordered and disordered regions of the Origin Recognition Complex direct differential in vivo binding at distinct motif sequences. Nucleic Acids Res 2024:gkae249. [PMID: 38597680 DOI: 10.1093/nar/gkae249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 03/16/2024] [Accepted: 04/09/2024] [Indexed: 04/11/2024] Open
Abstract
The Origin Recognition Complex (ORC) seeds replication-fork formation by binding to DNA replication origins, which in budding yeast contain a 17bp DNA motif. High resolution structure of the ORC-DNA complex revealed two base-interacting elements: a disordered basic patch (Orc1-BP4) and an insertion helix (Orc4-IH). To define the ORC elements guiding its DNA binding in vivo, we mapped genomic locations of 38 designed ORC mutants, revealing that different ORC elements guide binding at different sites. At silencing-associated sites lacking the motif, ORC binding and activity were fully explained by a BAH domain. Within replication origins, we reveal two dominating motif variants showing differential binding modes and symmetry: a non-repetitive motif whose binding requires Orc1-BP4 and Orc4-IH, and a repetitive one where another basic patch, Orc1-BP3, can replace Orc4-IH. Disordered basic patches are therefore key for ORC-motif binding in vivo, and we discuss how these conserved, minor-groove interacting elements can guide specific ORC-DNA recognition.
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Affiliation(s)
- Michal Chappleboim
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Segev Naveh-Tassa
- Department of Chemical and structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Miri Carmi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Yaakov Levy
- Department of Chemical and structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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2
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Mindel V, Brodsky S, Cohen A, Manadre W, Jonas F, Carmi M, Barkai N. Intrinsically disordered regions of the Msn2 transcription factor encode multiple functions using interwoven sequence grammars. Nucleic Acids Res 2024; 52:2260-2272. [PMID: 38109289 PMCID: PMC10954448 DOI: 10.1093/nar/gkad1191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 11/04/2023] [Accepted: 12/11/2023] [Indexed: 12/20/2023] Open
Abstract
Intrinsically disordered regions (IDRs) are abundant in eukaryotic proteins, but their sequence-function relationship remains poorly understood. IDRs of transcription factors (TFs) can direct promoter selection and recruit coactivators, as shown for the budding yeast TF Msn2. To examine how IDRs encode both these functions, we compared genomic binding specificity, coactivator recruitment, and gene induction amongst a large set of designed Msn2-IDR mutants. We find that both functions depend on multiple regions across the > 600AA IDR. Yet, transcription activity was readily disrupted by mutations that showed no effect on the Msn2 binding specificity. Our data attribute this differential sensitivity to the integration of a relaxed, composition-based code directing binding specificity with a more stringent, motif-based code controlling the recruitment of coactivators and transcription activity. Therefore, Msn2 utilizes interwoven sequence grammars for encoding multiple functions, suggesting a new IDR design paradigm of potentially general use.
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Affiliation(s)
- Vladimir Mindel
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Sagie Brodsky
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Aileen Cohen
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Wajd Manadre
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Miri Carmi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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3
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Lupo O, Kumar DK, Livne R, Chappleboim M, Levy I, Barkai N. The architecture of binding cooperativity between densely bound transcription factors. Cell Syst 2023; 14:732-745.e5. [PMID: 37527656 DOI: 10.1016/j.cels.2023.06.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 05/23/2023] [Accepted: 06/27/2023] [Indexed: 08/03/2023]
Abstract
The binding of transcription factors (TFs) along genomes is restricted to a subset of sites containing their preferred motifs. TF-binding specificity is often attributed to the co-binding of interacting TFs; however, apart from specific examples, this model remains untested. Here, we define dependencies among budding yeast TFs that localize to overlapping promoters by profiling the genome-wide consequences of co-depleting multiple TFs. We describe unidirectional interactions, revealing Msn2 as a central factor allowing TF binding at its target promoters. By contrast, no case of mutual cooperation was observed. Particularly, Msn2 retained binding at its preferred promoters upon co-depletion of fourteen similarly bound TFs. Overall, the consequences of TF co-depletions were moderate, limited to a subset of promoters, and failed to explain the role of regions outside the DNA-binding domain in directing TF-binding preferences. Our results call for re-evaluating the role of cooperative interactions in directing TF-binding preferences.
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Affiliation(s)
- Offir Lupo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Divya Krishna Kumar
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Rotem Livne
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Michal Chappleboim
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Idan Levy
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
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4
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Jonas F, Vidavski M, Benuck E, Barkai N, Yaakov G. Nucleosome retention by histone chaperones and remodelers occludes pervasive DNA-protein binding. Nucleic Acids Res 2023; 51:8496-8513. [PMID: 37493599 PMCID: PMC10484674 DOI: 10.1093/nar/gkad615] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 06/07/2023] [Accepted: 07/11/2023] [Indexed: 07/27/2023] Open
Abstract
DNA packaging within chromatin depends on histone chaperones and remodelers that form and position nucleosomes. Cells express multiple such chromatin regulators with overlapping in-vitro activities. Defining specific in-vivo activities requires monitoring histone dynamics during regulator depletion, which has been technically challenging. We have recently generated histone-exchange sensors in Saccharomyces cerevisiae, which we now use to define the contributions of 15 regulators to histone dynamics genome-wide. While replication-independent exchange in unperturbed cells maps to promoters, regulator depletions primarily affected gene bodies. Depletion of Spt6, Spt16 or Chd1 sharply increased nucleosome replacement sequentially at the beginning, middle or end of highly expressed gene bodies. They further triggered re-localization of chaperones to affected gene body regions, which compensated for nucleosome loss during transcription complex passage, but concurred with extensive TF binding in gene bodies. We provide a unified quantitative screen highlighting regulator roles in retaining nucleosome binding during transcription and preserving genomic packaging.
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Affiliation(s)
- Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Matan Vidavski
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Eli Benuck
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Gilad Yaakov
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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5
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Dunjić M, Jonas F, Yaakov G, More R, Mayshar Y, Rais Y, Orenbuch AH, Cheng S, Barkai N, Stelzer Y. Histone exchange sensors reveal variant specific dynamics in mouse embryonic stem cells. Nat Commun 2023; 14:3791. [PMID: 37365167 DOI: 10.1038/s41467-023-39477-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 06/15/2023] [Indexed: 06/28/2023] Open
Abstract
Eviction of histones from nucleosomes and their exchange with newly synthesized or alternative variants is a central epigenetic determinant. Here, we define the genome-wide occupancy and exchange pattern of canonical and non-canonical histone variants in mouse embryonic stem cells by genetically encoded exchange sensors. While exchange of all measured variants scales with transcription, we describe variant-specific associations with transcription elongation and Polycomb binding. We found considerable exchange of H3.1 and H2B variants in heterochromatin and repeat elements, contrasting the occupancy and little exchange of H3.3 in these regions. This unexpected association between H3.3 occupancy and exchange of canonical variants is also evident in active promoters and enhancers, and further validated by reduced H3.1 dynamics following depletion of H3.3-specific chaperone, HIRA. Finally, analyzing transgenic mice harboring H3.1 or H3.3 sensors demonstrates the vast potential of this system for studying histone exchange and its impact on gene expression regulation in vivo.
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Affiliation(s)
- Marko Dunjić
- Department of Molecular Cell Biology, Weizmann Institute of Science, 7610001, Rehovot, Israel
| | - Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science, 7610001, Rehovot, Israel
| | - Gilad Yaakov
- Department of Molecular Genetics, Weizmann Institute of Science, 7610001, Rehovot, Israel
| | - Roye More
- Department of Molecular Cell Biology, Weizmann Institute of Science, 7610001, Rehovot, Israel
| | - Yoav Mayshar
- Department of Molecular Cell Biology, Weizmann Institute of Science, 7610001, Rehovot, Israel
| | - Yoach Rais
- Department of Molecular Cell Biology, Weizmann Institute of Science, 7610001, Rehovot, Israel
| | | | - Saifeng Cheng
- Department of Molecular Cell Biology, Weizmann Institute of Science, 7610001, Rehovot, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, 7610001, Rehovot, Israel
| | - Yonatan Stelzer
- Department of Molecular Cell Biology, Weizmann Institute of Science, 7610001, Rehovot, Israel.
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6
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Jonas F, Carmi M, Krupkin B, Steinberger J, Brodsky S, Jana T, Barkai N. The molecular grammar of protein disorder guiding genome-binding locations. Nucleic Acids Res 2023; 51:4831-4844. [PMID: 36938874 PMCID: PMC10250222 DOI: 10.1093/nar/gkad184] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 01/25/2023] [Accepted: 03/15/2023] [Indexed: 03/21/2023] Open
Abstract
Intrinsically disordered regions (IDRs) direct transcription factors (TFs) towards selected genomic occurrences of their binding motif, as exemplified by budding yeast's Msn2. However, the sequence basis of IDR-directed TF binding selectivity remains unknown. To reveal this sequence grammar, we analyze the genomic localizations of >100 designed IDR mutants, each carrying up to 122 mutations within this 567-AA region. Our data points at multivalent interactions, carried by hydrophobic-mostly aliphatic-residues dispersed within a disordered environment and independent of linear sequence motifs, as the key determinants of Msn2 genomic localization. The implications of our results for the mechanistic basis of IDR-based TF binding preferences are discussed.
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Affiliation(s)
- Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Miri Carmi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Beniamin Krupkin
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Joseph Steinberger
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Sagie Brodsky
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Tamar Jana
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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7
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Kumar DK, Jonas F, Jana T, Brodsky S, Carmi M, Barkai N. Complementary strategies for directing in vivo transcription factor binding through DNA binding domains and intrinsically disordered regions. Mol Cell 2023; 83:1462-1473.e5. [PMID: 37116493 DOI: 10.1016/j.molcel.2023.04.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 01/17/2023] [Accepted: 01/30/2023] [Indexed: 04/30/2023]
Abstract
DNA binding domains (DBDs) of transcription factors (TFs) recognize DNA sequence motifs that are highly abundant in genomes. Within cells, TFs bind a subset of motif-containing sites as directed by either their DBDs or DBD-external (nonDBD) sequences. To define the relative roles of DBDs and nonDBDs in directing binding preferences, we compared the genome-wide binding of 48 (∼30%) budding yeast TFs with their DBD-only, nonDBD-truncated, and nonDBD-only mutants. With a few exceptions, binding locations differed between DBDs and TFs, resulting from the cumulative action of multiple determinants mapped mostly to disordered nonDBD regions. Furthermore, TFs' preferences for promoters of the fuzzy nucleosome architecture were lost in DBD-only mutants, whose binding spread across promoters, implicating nonDBDs' preferences in this hallmark of budding yeast regulatory design. We conclude that DBDs and nonDBDs employ complementary DNA-targeting strategies, whose balance defines TF binding specificity along genomes.
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Affiliation(s)
- Divya Krishna Kumar
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Tamar Jana
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Sagie Brodsky
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Miri Carmi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
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8
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Krieger G, Lupo O, Wittkopp P, Barkai N. Evolution of transcription factor binding through sequence variations and turnover of binding sites. Genome Res 2022; 32:1099-1111. [PMID: 35618416 DOI: 10.1101/gr.276715.122] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 05/20/2022] [Indexed: 01/08/2023]
Abstract
Variations in noncoding regulatory sequences play a central role in evolution. Interpreting such variations, however, remains difficult even in the context of defined attributes such as transcription factor (TF) binding sites. Here, we systematically link variations in cis-regulatory sequences to TF binding by profiling the allele-specific binding of 27 TFs expressed in a yeast hybrid, in which two related genomes are present within the same nucleus. TFs localize preferentially to sites containing their known consensus motifs but occupy only a small fraction of the motif-containing sites available within the genomes. Differential binding of TFs to the orthologous alleles was well explained by variations that alter motif sequence, whereas differences in chromatin accessibility between alleles were of little apparent effect. Motif variations that abolished binding when present in only one allele were still bound when present in both alleles, suggesting evolutionary compensation, with a potential role for sequence conservation at the motif's vicinity. At the level of the full promoter, we identify cases of binding-site turnover, in which binding sites are reciprocally gained and lost, yet most interspecific differences remained uncompensated. Our results show the flexibility of TFs to bind imprecise motifs and the fast evolution of TF binding sites between related species.
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Affiliation(s)
- Gat Krieger
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Offir Lupo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Patricia Wittkopp
- Department of Ecology and Evolutionary Biology, Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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9
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Jonas F, Yaakov G, Barkai N. Rtt109 promotes nucleosome replacement ahead of the replication fork. Genome Res 2022; 32:1089-1098. [PMID: 35609993 DOI: 10.1101/gr.276674.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 05/05/2022] [Indexed: 11/25/2022]
Abstract
DNA replication perturbs chromatin by triggering the eviction, replacement, and incorporation of nucleosomes. How this dynamic is orchestrated in time and space is poorly understood. Here, we apply a genetically encoded sensor for histone exchange to follow the time-resolved histone H3 exchange profile in budding yeast cells undergoing slow synchronous replication in nucleotide-limiting conditions. We find that new histones are incorporated not only behind, but also ahead of the replication fork. We provide evidence that Rtt109, the S-phase-induced acetyltransferase, stabilizes nucleosomes behind the fork but promotes H3 replacement ahead of the fork. Increased replacement ahead of the fork is independent of the primary Rtt109 acetylation target H3K56 and rather results from Vps75-dependent Rtt109 activity toward the H3 N terminus. Our results suggest that, at least under nucleotide-limiting conditions, selective incorporation of differentially modified H3s behind and ahead of the replication fork results in opposing effects on histone exchange, likely reflecting the distinct challenges for genome stability at these different regions.
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Affiliation(s)
- Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Gilad Yaakov
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
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10
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Gera T, Jonas F, More R, Barkai N. Evolution of binding preferences among whole-genome duplicated transcription factors. eLife 2022; 11:73225. [PMID: 35404235 PMCID: PMC9000951 DOI: 10.7554/elife.73225] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Accepted: 01/20/2022] [Indexed: 01/10/2023] Open
Abstract
Throughout evolution, new transcription factors (TFs) emerge by gene duplication, promoting growth and rewiring of transcriptional networks. How TF duplicates diverge was studied in a few cases only. To provide a genome-scale view, we considered the set of budding yeast TFs classified as whole-genome duplication (WGD)-retained paralogs (~35% of all specific TFs). Using high-resolution profiling, we find that ~60% of paralogs evolved differential binding preferences. We show that this divergence results primarily from variations outside the DNA-binding domains (DBDs), while DBD preferences remain largely conserved. Analysis of non-WGD orthologs revealed uneven splitting of ancestral preferences between duplicates, and the preferential acquiring of new targets by the least conserved paralog (biased neo/sub-functionalization). Interactions between paralogs were rare, and, when present, occurred through weak competition for DNA-binding or dependency between dimer-forming paralogs. We discuss the implications of our findings for the evolutionary design of transcriptional networks.
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Affiliation(s)
- Tamar Gera
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Roye More
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science
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11
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Carmon S, Jonas F, Barkai N, Schejter ED, Shilo BZ. Generation and timing of graded responses to morphogen gradients. Development 2021; 148:273784. [PMID: 34918740 PMCID: PMC8722393 DOI: 10.1242/dev.199991] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 11/17/2021] [Indexed: 11/20/2022]
Abstract
Morphogen gradients are known to subdivide a naive cell field into distinct zones of gene expression. Here, we examine whether morphogens can also induce a graded response within such domains. To this end, we explore the role of the Dorsal protein nuclear gradient along the dorsoventral axis in defining the graded pattern of actomyosin constriction that initiates gastrulation in early Drosophila embryos. Two complementary mechanisms for graded accumulation of mRNAs of crucial zygotic Dorsal target genes were identified. First, activation of target-gene expression expands over time from the ventral-most region of high nuclear Dorsal to lateral regions, where the levels are lower, as a result of a Dorsal-dependent activation probability of transcription sites. Thus, sites that are activated earlier will exhibit more mRNA accumulation. Second, once the sites are activated, the rate of RNA Polymerase II loading is also dependent on Dorsal levels. Morphological restrictions require that translation of the graded mRNA be delayed until completion of embryonic cell formation. Such timing is achieved by large introns, which provide a delay in production of the mature mRNAs. Spatio-temporal regulation of key zygotic genes therefore shapes the pattern of gastrulation.
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Affiliation(s)
- Shari Carmon
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Eyal D Schejter
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ben-Zion Shilo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
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12
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Hurst V, Challa K, Jonas F, Forey R, Sack R, Seebacher J, Schmid CD, Barkai N, Shimada K, Gasser SM, Poli J. A regulatory phosphorylation site on Mec1 controls chromatin occupancy of RNA polymerases during replication stress. EMBO J 2021; 40:e108439. [PMID: 34569643 PMCID: PMC8561635 DOI: 10.15252/embj.2021108439] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 09/08/2021] [Accepted: 09/10/2021] [Indexed: 01/16/2023] Open
Abstract
Upon replication stress, budding yeast checkpoint kinase Mec1ATR triggers the downregulation of transcription, thereby reducing the level of RNA polymerase (RNAP) on chromatin to facilitate replication fork progression. Here, we identify a hydroxyurea-induced phosphorylation site on Mec1, Mec1-S1991, that contributes to the eviction of RNAPII and RNAPIII during replication stress. The expression of the non-phosphorylatable mec1-S1991A mutant reduces replication fork progression genome-wide and compromises survival on hydroxyurea. This defect can be suppressed by destabilizing chromatin-bound RNAPII through a TAP fusion to its Rpb3 subunit, suggesting that lethality in mec1-S1991A mutants arises from replication-transcription conflicts. Coincident with a failure to repress gene expression on hydroxyurea in mec1-S1991A cells, highly transcribed genes such as GAL1 remain bound at nuclear pores. Consistently, we find that nuclear pore proteins and factors controlling RNAPII and RNAPIII are phosphorylated in a Mec1-dependent manner on hydroxyurea. Moreover, we show that Mec1 kinase also contributes to reduced RNAPII occupancy on chromatin during an unperturbed S phase by promoting degradation of the Rpb1 subunit.
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Affiliation(s)
- Verena Hurst
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, Basel, Switzerland
| | - Kiran Challa
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Felix Jonas
- Departments of Molecular Genetics and Physics of Complex Systems, Weizmann Institute of Science, Rehovot, Israel
| | - Romain Forey
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Equipe labélisée Ligue contre le Cancer, Montpellier, France
| | - Ragna Sack
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Jan Seebacher
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Christoph D Schmid
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Naama Barkai
- Departments of Molecular Genetics and Physics of Complex Systems, Weizmann Institute of Science, Rehovot, Israel
| | - Kenji Shimada
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Susan M Gasser
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, Basel, Switzerland
| | - Jérôme Poli
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,Institut de Génétique Humaine, CNRS, Université de Montpellier, Equipe labélisée Ligue contre le Cancer, Montpellier, France
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13
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Yaakov G, Jonas F, Barkai N. Publisher Correction: Measurement of histone replacement dynamics with genetically encoded exchange timers in yeast. Nat Biotechnol 2021; 39:1467. [PMID: 34584249 DOI: 10.1038/s41587-021-01103-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Gilad Yaakov
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
| | - Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
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14
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Brodsky S, Jana T, Barkai N. Order through disorder: The role of intrinsically disordered regions in transcription factor binding specificity. Curr Opin Struct Biol 2021; 71:110-115. [PMID: 34303077 DOI: 10.1016/j.sbi.2021.06.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 05/31/2021] [Accepted: 06/14/2021] [Indexed: 02/07/2023]
Abstract
Transcription factors (TFs) must bind at specific genomic locations to accurately regulate gene expression. The ability of TFs to recognize specific DNA sequence motifs arises from the inherent preferences of their globular DNA-binding domains (DBDs). Yet, these preferences are insufficient to explain the in vivo TF binding site selection. TFs are enriched with intrinsically disordered regions (IDRs), most of which are poorly characterized. While not generally considered as determinants of TF binding specificity, IDRs guide protein-protein interactions within transcriptional condensates, and multiple examples exist in which short IDRs flanking the DBD contribute to binding specificity via direct contact with the DNA. We recently reported that long IDRs, present away from the DBD, act as major specificity determinants at the genomic scale. Here, we discuss mechanisms through which IDRs contribute to DNA binding specificity, highlighting the role of long IDRs in dictating the in vivo binding site selection.
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Affiliation(s)
- Sagie Brodsky
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Tamar Jana
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 76100, Israel.
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15
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Bar-Ziv R, Brodsky S, Chapal M, Barkai N. Transcription Factor Binding to Replicated DNA. Cell Rep 2021; 30:3989-3995.e4. [PMID: 32209462 DOI: 10.1016/j.celrep.2020.02.114] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 01/13/2020] [Accepted: 02/27/2020] [Indexed: 11/17/2022] Open
Abstract
Genome replication perturbs the DNA regulatory environment by displacing DNA-bound proteins, replacing nucleosomes, and introducing dosage imbalance between regions replicating at different S-phase stages. Recently, we showed that these effects are integrated to maintain transcription homeostasis: replicated genes increase in dosage, but their expression remains stable due to replication-dependent epigenetic changes that suppress transcription. Here, we examine whether reduced transcription from replicated DNA results from limited accessibility to regulatory factors by measuring the time-resolved binding of RNA polymerase II (Pol II) and specific transcription factors (TFs) to DNA during S phase in budding yeast. We show that the Pol II binding pattern is largely insensitive to DNA dosage, indicating limited binding to replicated DNA. In contrast, binding of three TFs (Reb1, Abf1, and Rap1) to DNA increases with the increasing DNA dosage. We conclude that the replication-specific chromatin environment remains accessible to regulatory factors but suppresses RNA polymerase recruitment.
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Affiliation(s)
- Raz Bar-Ziv
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel; The Howard Hughes Medical Institute, University of California Berkeley, Berkeley, CA 94720, USA
| | - Sagie Brodsky
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Michal Chapal
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
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16
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Frenkel N, Jonas F, Carmi M, Yaakov G, Barkai N. Rtt109 slows replication speed by histone N-terminal acetylation. Genome Res 2021; 31:426-435. [PMID: 33563717 PMCID: PMC7919450 DOI: 10.1101/gr.266510.120] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 12/28/2020] [Indexed: 01/17/2023]
Abstract
The wrapping of DNA around histone octamers challenges processes that use DNA as their template. In vitro, DNA replication through chromatin depends on histone modifiers, raising the possibility that cells modify histones to optimize fork progression. Rtt109 is an acetyl transferase that acetylates histone H3 before its DNA incorporation on the K56 and N-terminal residues. We previously reported that, in budding yeast, a wave of histone H3 K9 acetylation progresses ∼3–5 kb ahead of the replication fork. Whether this wave contributes to replication dynamics remained unknown. Here, we show that the replication fork velocity increases following deletion of RTT109, the gene encoding the enzyme required for the prereplication H3 acetylation wave. By using histone H3 mutants, we find that Rtt109-dependent N-terminal acetylation regulates fork velocity, whereas K56 acetylation contributes to replication dynamics only when N-terminal acetylation is compromised. We propose that acetylation of newly synthesized histones slows replication by promoting replacement of nucleosomes evicted by the incoming fork, thereby protecting genome integrity.
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Affiliation(s)
- Nelly Frenkel
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Miri Carmi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Gilad Yaakov
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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17
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Lupo O, Krieger G, Jonas F, Barkai N. Accumulation of cis- and trans-regulatory variations is associated with phenotypic divergence of a complex trait between yeast species. G3 (Bethesda) 2021; 11:6121923. [PMID: 33609368 PMCID: PMC8022985 DOI: 10.1093/g3journal/jkab016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Accepted: 01/07/2021] [Indexed: 11/15/2022]
Abstract
Gene regulatory variations accumulate during evolution and alter gene expression. While the importance of expression variation in phenotypic evolution is well established, the molecular basis remains largely unknown. Here, we examine two closely related yeast species, Saccharomyces cerevisiae and Saccharomyces paradoxus, which show phenotypical differences in morphology and cell cycle progression when grown in the same environment. By profiling the cell cycle transcriptome and binding of key transcription factors (TFs) in the two species and their hybrid, we show that changes in expression levels and dynamics of oscillating genes are dominated by upstream trans-variations. We find that multiple cell cycle regulators show both cis- and trans-regulatory variations, which alters their expression in favor of the different cell cycle phenotypes. Moreover, we show that variations in the cell cycle TFs, Fkh1, and Fkh2 affect both the expression of target genes, and the binding specificity of an interacting TF, Ace2. Our study reveals how multiple variations accumulate and propagate through the gene regulatory network, alter TFs binding, contributing to phenotypic changes in cell cycle progression.
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Affiliation(s)
- Offir Lupo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Gat Krieger
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.,Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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18
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Jana T, Brodsky S, Barkai N. Speed-Specificity Trade-Offs in the Transcription Factors Search for Their Genomic Binding Sites. Trends Genet 2021; 37:421-432. [PMID: 33414013 DOI: 10.1016/j.tig.2020.12.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 12/04/2020] [Accepted: 12/07/2020] [Indexed: 12/17/2022]
Abstract
Transcription factors (TFs) regulate gene expression by binding DNA sequences recognized by their DNA-binding domains (DBDs). DBD-recognized motifs are short and highly abundant in genomes. The ability of TFs to bind a specific subset of motif-containing sites, and to do so rapidly upon activation, is fundamental for gene expression in all eukaryotes. Despite extensive interest, our understanding of the TF-target search process is fragmented; although binding specificity and detection speed are two facets of this same process, trade-offs between them are rarely addressed. In this opinion article, we discuss potential speed-specificity trade-offs in the context of existing models. We further discuss the recently described 'distributed specificity' paradigm, suggesting that intrinsically disordered regions (IDRs) promote specificity while reducing the TF-target search time.
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Affiliation(s)
- Tamar Jana
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Sagie Brodsky
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
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19
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Affiliation(s)
- Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
| | - Ben-Zion Shilo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
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20
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Brodsky S, Jana T, Mittelman K, Chapal M, Kumar DK, Carmi M, Barkai N. Intrinsically Disordered Regions Direct Transcription Factor In Vivo Binding Specificity. Mol Cell 2020; 79:459-471.e4. [DOI: 10.1016/j.molcel.2020.05.032] [Citation(s) in RCA: 99] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 03/10/2020] [Accepted: 05/21/2020] [Indexed: 11/25/2022]
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21
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Krieger G, Lupo O, Levy AA, Barkai N. Independent evolution of transcript abundance and gene regulatory dynamics. Genome Res 2020; 30:1000-1011. [PMID: 32699020 PMCID: PMC7397873 DOI: 10.1101/gr.261537.120] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 06/24/2020] [Indexed: 12/13/2022]
Abstract
Changes in gene expression drive novel phenotypes, raising interest in how gene expression evolves. In contrast to the static genome, cells modulate gene expression in response to changing environments. Previous comparative studies focused on specific conditions, describing interspecies variation in expression levels, but providing limited information about variation across different conditions. To close this gap, we profiled mRNA levels of two related yeast species in hundreds of conditions and used coexpression analysis to distinguish variation in the dynamic pattern of gene expression from variation in expression levels. The majority of genes whose expression varied between the species maintained a conserved dynamic pattern. Cases of diverged dynamic pattern correspond to genes that were induced under distinct subsets of conditions in the two species. Profiling the interspecific hybrid allowed us to distinguish between genes with predominantly cis- or trans-regulatory variation. We find that trans-varying alleles are dominantly inherited, and that cis-variations are often complemented by variations in trans Based on these results, we suggest that gene expression diverges primarily through changes in expression levels, but does not alter the pattern by which these levels are dynamically regulated.
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Affiliation(s)
- Gat Krieger
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Offir Lupo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Avraham A Levy
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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22
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Jonas F, Soifer I, Barkai N. A Visual Framework for Classifying Determinants of Cell Size. Cell Rep 2019; 25:3519-3529.e2. [PMID: 30566874 PMCID: PMC6315284 DOI: 10.1016/j.celrep.2018.11.087] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 09/19/2018] [Accepted: 11/20/2018] [Indexed: 12/04/2022] Open
Abstract
Cells control their size by coordinating cell cycle progression with volume growth. Size control is typically studied at specific cell cycle transitions that are delayed or accelerated depending on size. This focus is well suited for revealing mechanisms acting at these transitions, but neglects the dynamics in other cell cycle phases, and is therefore inherently limited for studying how the characteristic cell size is determined. We address this limitation through a formalism that intuitively visualizes the characteristic size emerging from integrated cell cycle dynamics of individual cells. Applying this formalism to budding yeast, we describe the contributions of the un-budded (G1) and budded (S-G2-M) phase to size adjustments following environmental or genetic perturbations. We show that although the budded phase can be perturbed with little consequences for G1 dynamics, perturbations in G1 propagate to the budded phase. Our study provides an integrated view on cell size determinants in budding yeast. An intuitive visualization framework for cell size control is described Cell size control in different environments or mutant backgrounds can be compared Mutual dependencies between size control at different cell cycle phases are described
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Affiliation(s)
- Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Ilya Soifer
- Calico Labs, South San Francisco, CA 94080, USA
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
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23
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Abstract
Gene duplication promotes adaptive evolution in two main ways: allowing one duplicate to evolve a new function and splitting ancestral functions between the duplicates. The second scenario may resolve adaptive conflicts that can rise when one gene performs different functions. In an apparent departure from both scenarios, low-expressing transcription factor (TF) duplicates commonly bind to the same DNA motifs and act in overlapping conditions. To examine for possible benefits of this apparent redundancy, we examined the Msn2 and Msn4 duplicates in budding yeast. We show that Msn2,4 function as one unit by inducing the same set of target genes in overlapping conditions. Yet, the two-factor composition allows this unit’s expression to be both environmentally responsive and with low noise, resolving an adaptive conflict that limits expression of single genes. We propose that duplication can provide adaptive benefit through cooperation rather than functional divergence, allowing two-factor dynamics with beneficial properties that cannot be achieved by a single gene. Gene expression tuning is limited by a conflict between expression plasticity and expression noise. This study shows that duplicated genes can resolve this conflict by functioning as one unit with expression control that is both environmentally responsive and low-noise, revealing a new adaptive benefit of duplication.
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Affiliation(s)
- Michal Chapal
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Sefi Mintzer
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Sagie Brodsky
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Miri Carmi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
- * E-mail:
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24
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Rahimi N, Averbukh I, Carmon S, Schejter ED, Barkai N, Shilo BZ. Dynamics of Spaetzle morphogen shuttling in the Drosophila embryo shapes gastrulation patterning. Development 2019; 146:146/21/dev181487. [PMID: 31719046 DOI: 10.1242/dev.181487] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 10/07/2019] [Indexed: 12/27/2022]
Abstract
Establishment of morphogen gradients in the early Drosophila embryo is challenged by a diffusible sextracellular milieu, and by rapid nuclear divisions that occur at the same time. To understand how a sharp gradient is formed within this dynamic environment, we followed the generation of graded nuclear Dorsal protein, the hallmark of pattern formation along the dorso-ventral axis, in live embryos. The dynamics indicate that a sharp extracellular gradient is formed through diffusion-based shuttling of the Spaetzle (Spz) morphogen that progresses through several nuclear divisions. Perturbed shuttling in wntD mutant embryos results in a flat activation peak and aberrant gastrulation. Re-entry of Dorsal into the nuclei at the final division cycle plays an instructive role, as the residence time of Dorsal in each nucleus is translated to the amount of zygotic transcript that will be produced, thereby guiding graded accumulation of specific zygotic transcripts that drive patterned gastrulation. We conclude that diffusion-based ligand shuttling, coupled with dynamic readout, establishes a refined pattern within the diffusible environment of early embryos.
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Affiliation(s)
- Neta Rahimi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Inna Averbukh
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Shari Carmon
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Eyal D Schejter
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ben-Zion Shilo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
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25
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Averbukh I, Lai SL, Doe CQ, Barkai N. A repressor-decay timer for robust temporal patterning in embryonic Drosophila neuroblast lineages. eLife 2018; 7:38631. [PMID: 30526852 PMCID: PMC6303102 DOI: 10.7554/elife.38631] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 12/10/2018] [Indexed: 11/13/2022] Open
Abstract
Biological timers synchronize patterning processes during embryonic development. In the Drosophila embryo, neural progenitors (neuroblasts; NBs) produce a sequence of unique neurons whose identities depend on the sequential expression of temporal transcription factors (TTFs). The stereotypy and precision of NB lineages indicate reproducible TTF timer progression. We combine theory and experiments to define the timer mechanism. The TTF timer is commonly described as a relay of activators, but its regulatory circuit is also consistent with a repressor-decay timer, where TTF expression begins when its repressor decays. Theory shows that repressor-decay timers are more robust to parameter variations than activator-relay timers. This motivated us to experimentally compare the relative importance of the relay and decay interactions in vivo. Comparing WT and mutant NBs at high temporal resolution, we show that the TTF sequence progresses primarily by repressor-decay. We suggest that need for robust performance shapes the evolutionary-selected designs of biological circuits.
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Affiliation(s)
- Inna Averbukh
- Department of Molecular Genetics, Weizmann institute of science, Rehovot, Israel
| | - Sen-Lin Lai
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Chris Q Doe
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann institute of science, Rehovot, Israel
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26
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Voichek Y, Mittelman K, Gordon Y, Bar-Ziv R, Lifshitz Smit D, Shenhav R, Barkai N. Epigenetic Control of Expression Homeostasis during Replication Is Stabilized by the Replication Checkpoint. Mol Cell 2018; 70:1121-1133.e9. [PMID: 29910110 DOI: 10.1016/j.molcel.2018.05.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 03/22/2018] [Accepted: 05/11/2018] [Indexed: 11/24/2022]
Abstract
DNA replication introduces a dosage imbalance between early and late replicating genes. In budding yeast, buffering gene expression against this imbalance depends on marking replicated DNA by H3K56 acetylation (H3K56ac). Whether additional processes are required for suppressing transcription from H3K56ac-labeled DNA remains unknown. Here, using a database-guided candidate screen, we find that COMPASS, the H3K4 methyltransferase, and its upstream effector, PAF1C, act downstream of H3K56ac to buffer expression. Replicated genes show reduced abundance of the transcription activating mark H3K4me3 and accumulate the transcription inhibitory mark H3K4me2 near transcription start sites. Notably, in hydroxyurea-exposed cells, the S phase checkpoint stabilizes H3K56ac and becomes essential for buffering. We suggest that H3K56ac suppresses transcription of replicated genes by interfering with post-replication recovery of epigenetic marks and assign a new function for the S phase checkpoint in stabilizing this mechanism during persistent dosage imbalance.
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Affiliation(s)
- Yoav Voichek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Karin Mittelman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yulia Gordon
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Raz Bar-Ziv
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - David Lifshitz Smit
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Rom Shenhav
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
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27
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Abstract
Growing cells are subject to cycles of nutrient depletion and repletion. A shortage of nutrients activates a starvation program that promotes growth in limiting conditions. To examine whether nutrient-deprived cells prepare also for their subsequent recovery, we followed the transcription program activated in budding yeast transferred to low-phosphate media and defined its contribution to cell growth during phosphate limitation and upon recovery. An initial transcription wave was induced by moderate phosphate depletion that did not affect cell growth. A second transcription wave followed when phosphate became growth limiting. The starvation program contributed to growth only in the second, growth-limiting phase. Notably, the early response, activated at moderate depletion, promoted recovery from starvation by increasing phosphate influx upon transfer to rich medium. Our results suggest that cells subject to nutrient depletion prepare not only for growth in the limiting conditions but also for their predicted recovery once nutrients are replenished.
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Affiliation(s)
- Yonat Gurvich
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Dena Leshkowitz
- Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
- * E-mail:
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28
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29
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Metzl-Raz E, Kafri M, Yaakov G, Soifer I, Gurvich Y, Barkai N. Principles of cellular resource allocation revealed by condition-dependent proteome profiling. eLife 2017; 6:28034. [PMID: 28857745 PMCID: PMC5578734 DOI: 10.7554/elife.28034] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 08/08/2017] [Indexed: 12/23/2022] Open
Abstract
Growing cells coordinate protein translation with metabolic rates. Central to this coordination is ribosome production. Ribosomes drive cell growth, but translation of ribosomal proteins competes with production of non-ribosomal proteins. Theory shows that cell growth is maximized when all expressed ribosomes are constantly translating. To examine whether budding yeast function at this limit of full ribosomal usage, we profiled the proteomes of cells growing in different environments. We find that cells produce excess ribosomal proteins, amounting to a constant ≈8% of the proteome. Accordingly, ≈25% of ribosomal proteins expressed in rapidly growing cells does not contribute to translation. Further, this fraction increases as growth rate decreases and these excess ribosomal proteins are employed when translation demands unexpectedly increase. We suggest that steadily growing cells prepare for conditions that demand increased translation by producing excess ribosomes, at the expense of lower steady-state growth rate.
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Affiliation(s)
- Eyal Metzl-Raz
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Moshe Kafri
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Gilad Yaakov
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Ilya Soifer
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Yonat Gurvich
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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30
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Fainsod A, Leibovich A, Leibovich-Kot H, Ben-Zvi D, Barkai N. Expansion-restriction of Spemann's organizer by an ADMP self-regulatory switch to scale the BMP gradient. Mech Dev 2017. [DOI: 10.1016/j.mod.2017.04.180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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31
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Abstract
Activation of extracellular signal regulated kinase (ERK) is used by many signaling pathways to control tissue patterning in a broad range of multicellular organisms. In this issue of Developmental Cell, Johnson et al. (2017) provide an optogenetic approach to manipulate this pathway with high precision and explore its signaling code.
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Affiliation(s)
- Ben-Zion Shilo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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32
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Abstract
Chromatin can function as an integrator of DNA-related processes, allowing communication, for example, between DNA replication and gene transcription. Such communication is needed to overcome the gene-dosage imbalance introduced during DNA replication, when certain genes are replicated prior to others. Increased transcription of early replicating genes could alter regulatory balances. This does not occur, suggesting a mechanism that suppresses expression from newly replicated DNA. Critical to this buffering is Rtt109, which acetylates the internal K56 residue of newly synthesized histone H3 prior to incorporation onto DNA. H3K56ac distinguishes replicated from non-replicated DNA, communicating this information to the transcription machinery to ensure expression homeostasis during S phase.
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Affiliation(s)
- Yoav Voichek
- a Department of Molecular Genetics , Weizmann Institute of Science , Rehovot , Israel
| | - Raz Bar-Ziv
- a Department of Molecular Genetics , Weizmann Institute of Science , Rehovot , Israel
| | - Naama Barkai
- a Department of Molecular Genetics , Weizmann Institute of Science , Rehovot , Israel
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33
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Herbst RH, Bar-Zvi D, Reikhav S, Soifer I, Breker M, Jona G, Shimoni E, Schuldiner M, Levy AA, Barkai N. Heterosis as a consequence of regulatory incompatibility. BMC Biol 2017; 15:38. [PMID: 28494792 PMCID: PMC5426048 DOI: 10.1186/s12915-017-0373-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 04/11/2017] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND The merging of genomes in inter-specific hybrids can result in novel phenotypes, including increased growth rate and biomass yield, a phenomenon known as heterosis. Heterosis is typically viewed as the opposite of hybrid incompatibility. In this view, the superior performance of the hybrid is attributed to heterozygote combinations that compensate for deleterious mutations accumulating in each individual genome, or lead to new, over-dominating interactions with improved performance. Still, only fragmented knowledge is available on genes and processes contributing to heterosis. RESULTS We describe a budding yeast hybrid that grows faster than both its parents under different environments. Phenotypically, the hybrid progresses more rapidly through cell cycle checkpoints, relieves the repression of respiration in fast growing conditions, does not slow down its growth when presented with ethanol stress, and shows increased signs of DNA damage. A systematic genetic screen identified hundreds of S. cerevisiae alleles whose deletion reduced growth of the hybrid. These growth-affecting alleles were condition-dependent, and differed greatly from alleles that reduced the growth of the S. cerevisiae parent. CONCLUSIONS Our results define a budding yeast hybrid that is perturbed in multiple regulatory processes but still shows a clear growth heterosis. We propose that heterosis results from incompatibilities that perturb regulatory mechanisms, which evolved to protect cells against damage or prepare them for future challenges by limiting cell growth.
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Affiliation(s)
- Rebecca H Herbst
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7610001, Israel
- Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
- Department of Systems Biology, Harvard Medical School, Boston, MA, 02114, USA
| | - Dana Bar-Zvi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Sharon Reikhav
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Ilya Soifer
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7610001, Israel
- Current affiliation: Calico Labs, South San Francisco, CA, 94080, USA
| | - Michal Breker
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Ghil Jona
- Department of Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Eyal Shimoni
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Avraham A Levy
- Plant and Environmental Sciences Department, Weizmann Institute of Science, Rehovot, 7610001, Israel.
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7610001, Israel.
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Shilo BZ, Barkai N. Buffering Global Variability of Morphogen Gradients. Dev Cell 2017; 40:429-438. [DOI: 10.1016/j.devcel.2016.12.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 10/14/2016] [Accepted: 12/05/2016] [Indexed: 12/23/2022]
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Yaakov G, Lerner D, Bentele K, Steinberger J, Barkai N. Coupling phenotypic persistence to DNA damage increases genetic diversity in severe stress. Nat Ecol Evol 2017; 1:16. [PMID: 28812556 DOI: 10.1038/s41559-016-0016] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 10/13/2016] [Indexed: 12/30/2022]
Abstract
Mutation rate balances the need to protect genome integrity with the advantage of evolutionary innovations. Microorganisms increase their mutation rate when stressed, perhaps addressing the growing need for evolutionary innovation. Such a strategy, however, is only beneficial under moderate stresses that allow cells to divide and realize their mutagenic potential. In contrast, severe stresses rapidly kill the majority of the population with the exception of a small minority of cells that are in a phenotypically distinct state termed persistence. Although persisters were discovered many decades ago, the stochastic event triggering persistence is poorly understood. We report that spontaneous DNA damage triggers persistence in Saccharomyces cerevisiae by activating the general stress response, providing protection against a range of harsh stress and drug environments. We further show that the persister subpopulation carries an increased load of genetic variants in the form of insertions, deletions or large structural variations, which are unrelated to their stress survival. This coupling of DNA damage to phenotypic persistence may increase genetic diversity specifically in severe stress conditions, where diversity is beneficial but the ability to generate de novo mutations is limited.
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Affiliation(s)
- Gilad Yaakov
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - David Lerner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Kajetan Bentele
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Joseph Steinberger
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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36
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Abstract
Tissue stem cells produce a constant flux of differentiated cells with distinct proportions. Here, we show that stem cells in colonic crypts differentiate early to form precisely 1:3 ratio of secretory to absorptive cells. This precision is surprising, as there are only eight stem cells making irreversible fate decisions, and so large stochastic effects of this small pool should have yielded much larger noise in cell proportions. We use single molecule FISH, lineage‐tracing mice and simulations to identify the homeostatic mechanisms facilitating robust proportions. We find that Delta‐Notch lateral inhibition operates in a restricted spatial zone to reduce initial noise in cell proportions. Increased dwell time and dispersive migration of secretory cells further averages additional variability added during progenitor divisions and breaks up continuous patches of same‐fate cells. These noise‐reducing mechanisms resolve the trade‐off between early commitment and robust differentiation and ensure spatially uniform spread of secretory cells. Our findings may apply to other cases where small progenitor pools expand to give rise to precise tissue cell proportions.
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Affiliation(s)
- Beáta Tóth
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Shani Ben-Moshe
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Avishai Gavish
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Shalev Itzkovitz
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
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37
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Gispan A, Carmi M, Barkai N. Model-based analysis of DNA replication profiles: predicting replication fork velocity and initiation rate by profiling free-cycling cells. Genome Res 2016; 27:310-319. [PMID: 28028072 PMCID: PMC5287236 DOI: 10.1101/gr.205849.116] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 12/12/2016] [Indexed: 12/24/2022]
Abstract
Eukaryotic cells initiate DNA synthesis by sequential firing of hundreds of origins. This ordered replication is described by replication profiles, which measure the DNA content within a cell population. Here, we show that replication dynamics can be deduced from replication profiles of free-cycling cells. While such profiles lack explicit temporal information, they are sensitive to fork velocity and initiation capacity through the passive replication pattern, namely the replication of origins by forks emanating elsewhere. We apply our model-based approach to a compendium of profiles that include most viable budding yeast mutants implicated in replication. Predicted changes in fork velocity or initiation capacity are verified by profiling synchronously replicating cells. Notably, most mutants implicated in late (or early) origin effects are explained by global modulation of fork velocity or initiation capacity. Our approach provides a rigorous framework for analyzing DNA replication profiles of free-cycling cells.
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Affiliation(s)
- Ariel Gispan
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Miri Carmi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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38
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Abstract
The minimal description of a growing cell consists of self-replicating ribosomes translating the cellular proteome. While neglecting all other cellular components, this model provides key insights into the control and limitations of growth rate. It shows, for example, that growth rate is maximized when ribosomes work at full capacity, explains the linear relation between growth rate and the ribosome fraction of the proteome and defines the maximal possible growth rate. This ribosome-centered model also highlights the challenge of coordinating cell growth with related processes such as cell division or nutrient production. Coordination is promoted when ribosomes don't translate at maximal capacity, as it allows escaping strict exponential growth. Recent data support the notion that multiple cellular processes limit growth. In particular, increasing transcriptional demand may be as deleterious as increasing translational demand, depending on growth conditions. Consistent with the idea of trade-off, cells may forgo maximal growth to enable more efficient interprocess coordination and faster adaptation to changing conditions.
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Affiliation(s)
- Moshe Kafri
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Eyal Metzl-Raz
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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39
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Bar-Ziv R, Voichek Y, Barkai N. Dealing with Gene-Dosage Imbalance during S Phase. Trends Genet 2016; 32:717-723. [PMID: 27575299 DOI: 10.1016/j.tig.2016.08.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 08/09/2016] [Accepted: 08/12/2016] [Indexed: 12/01/2022]
Abstract
DNA replication perturbs the dosage balance between genes that replicate early during S phase and those that replicate late. If propagated to influence protein content, this dosage imbalance could influence cellular functions. In bacteria, mechanisms have evolved to use this imbalance to tune certain processes with the rate of cell growth. By contrast, eukaryotes buffer this dosage imbalance to ensure gene expression homeostasis also during S phase. Here, we outline classical and more recent studies describing how different organisms deal with this replication-dependent dosage imbalance, and describe recent results linking the eukaryotic buffering mechanism to replication-dependent histone acetylation. Finally, we discuss the possible implications of this buffering mechanism and speculate why it is specific to eukaryote cells.
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Affiliation(s)
- Raz Bar-Ziv
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yoav Voichek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
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40
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Tamari Z, Yona AH, Pilpel Y, Barkai N. Rapid evolutionary adaptation to growth on an 'unfamiliar' carbon source. BMC Genomics 2016; 17:674. [PMID: 27552923 PMCID: PMC5477773 DOI: 10.1186/s12864-016-3010-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 08/11/2016] [Indexed: 11/10/2022] Open
Abstract
Background Cells constantly adapt to changes in their environment. When environment shifts between conditions that were previously encountered during the course of evolution, evolutionary-programmed responses are possible. Cells, however, may also encounter a new environment to which a novel response is required. To characterize the first steps in adaptation to a novel condition, we studied budding yeast growth on xylulose, a sugar that is very rarely found in the wild. Results We previously reported that growth on xylulose induces the expression of amino acid biosynthesis genes in multiple natural yeast isolates. This induction occurs despite the presence of amino acids in the growth medium and is a unique response to xylulose, not triggered by naturally available carbon sources. Propagating these strains for ~300 generations on xylulose significantly improved their growth rate. Notably, the most significant change in gene expression was the loss of amino acid biosynthesis gene induction. Furthermore, the reduction in amino-acid biosynthesis gene expression on xylulose was tightly correlated with the improvement in growth rate, suggesting that internal depletion of amino-acids presented a major bottleneck limiting growth in xylulose. Conclusions We discuss the possible implications of our results for explaining how cells maintain the balance between supply and demand of amino acids during growth in evolutionary ‘familiar’ vs. ‘novel’ conditions. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-3010-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Zvi Tamari
- Department of molecular genetics, Weizmann institute of science, Rehovot, 76100, Israel.
| | - Avihu H Yona
- Department of molecular genetics, Weizmann institute of science, Rehovot, 76100, Israel
| | - Yitzhak Pilpel
- Department of molecular genetics, Weizmann institute of science, Rehovot, 76100, Israel
| | - Naama Barkai
- Department of molecular genetics, Weizmann institute of science, Rehovot, 76100, Israel
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41
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Rahimi N, Averbukh I, Haskel-Ittah M, Degani N, Schejter ED, Barkai N, Shilo BZ. A WntD-Dependent Integral Feedback Loop Attenuates Variability in Drosophila Toll Signaling. Dev Cell 2016; 36:401-14. [PMID: 26906736 DOI: 10.1016/j.devcel.2016.01.023] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 11/22/2015] [Accepted: 01/27/2016] [Indexed: 12/25/2022]
Abstract
Patterning by morphogen gradients relies on the capacity to generate reproducible distribution profiles. Morphogen spread depends on kinetic parameters, including diffusion and degradation rates, which vary between embryos, raising the question of how variability is controlled. We examined this in the context of Toll-dependent dorsoventral (DV) patterning of the Drosophila embryo. We find that low embryo-to-embryo variability in DV patterning relies on wntD, a Toll-target gene expressed initially at the posterior pole. WntD protein is secreted and disperses in the extracellular milieu, associates with its receptor Frizzled4, and inhibits the Toll pathway by blocking the Toll extracellular domain. Mathematical modeling predicts that WntD accumulates until the Toll gradient narrows to its desired spread, and we support this feedback experimentally. This circuit exemplifies a broadly applicable induction-contraction mechanism, which reduces patterning variability through a restricted morphogen-dependent expression of a secreted diffusible inhibitor.
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Affiliation(s)
- Neta Rahimi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Inna Averbukh
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Michal Haskel-Ittah
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Neta Degani
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Eyal D Schejter
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
| | - Ben-Zion Shilo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
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42
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Abstract
Chromatin is composed of DNA and histones, which provide a unified platform for regulating DNA-related processes, mostly through their post-translational modification. During DNA replication, histone arrangement is perturbed, first to allow progression of DNA polymerase and then during repackaging of the replicated DNA. To study how DNA replication influences the pattern of histone modification, we followed the cell-cycle dynamics of 10 histone marks in budding yeast. We find that histones deposited on newly replicated DNA are modified at different rates: While some marks appear immediately upon replication (e.g., H4K16ac, H3K4me1), others increase with transcription-dependent delays (e.g., H3K4me3, H3K36me3). Notably, H3K9ac was deposited as a wave preceding the replication fork by ∼5–6 kb. This replication-guided H3K9ac was fully dependent on the acetyltransferase Rtt109, while expression-guided H3K9ac was deposited by Gcn5. Further, topoisomerase depletion intensified H3K9ac in front of the replication fork and in sites where RNA polymerase II was trapped, suggesting supercoiling stresses trigger H3K9 acetylation. Our results assign complementary roles for DNA replication and gene expression in defining the pattern of histone modification.
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Affiliation(s)
- Raz Bar-Ziv
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yoav Voichek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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43
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Abstract
Genome replication introduces a stepwise increase in the DNA template available for transcription. Genes replicated early in S phase experience this increase before late-replicating genes, raising the question of how expression levels are affected by DNA replication. We show that in budding yeast, messenger RNA (mRNA) synthesis rate is buffered against changes in gene dosage during S phase. This expression homeostasis depends on acetylation of H3 on its internal K56 site by Rtt109/Asf1. Deleting these factors, mutating H3K56 or up-regulating its deacetylation, increases gene expression in S phase in proportion to gene replication timing. Therefore, H3K56 acetylation on newly deposited histones reduces transcription efficiency from replicated DNA, complementing its role in guarding genome stability. Our study provides molecular insight into the mechanism maintaining expression homeostasis during DNA replication.
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Affiliation(s)
- Yoav Voichek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Raz Bar-Ziv
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
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44
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Gavish A, Barkai N. A two-step patterning process increases the robustness of periodic patterning in the fly eye. J Biol Phys 2016; 42:317-38. [PMID: 26884095 DOI: 10.1007/s10867-016-9409-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 01/06/2016] [Indexed: 12/31/2022] Open
Abstract
Complex periodic patterns can self-organize through dynamic interactions between diffusible activators and inhibitors. In the biological context, self-organized patterning is challenged by spatial heterogeneities ('noise') inherent to biological systems. How spatial variability impacts the periodic patterning mechanism and how it can be buffered to ensure precise patterning is not well understood. We examine the effect of spatial heterogeneity on the periodic patterning of the fruit fly eye, an organ composed of ∼800 miniature eye units (ommatidia) whose periodic arrangement along a hexagonal lattice self-organizes during early stages of fly development. The patterning follows a two-step process, with an initial formation of evenly spaced clusters of ∼10 cells followed by a subsequent refinement of each cluster into a single selected cell. Using a probabilistic approach, we calculate the rate of patterning errors resulting from spatial heterogeneities in cell size, position and biosynthetic capacity. Notably, error rates were largely independent of the desired cluster size but followed the distributions of signaling speeds. Pre-formation of large clusters therefore greatly increases the reproducibility of the overall periodic arrangement, suggesting that the two-stage patterning process functions to guard the pattern against errors caused by spatial heterogeneities. Our results emphasize the constraints imposed on self-organized patterning mechanisms by the need to buffer stochastic effects. Author summary Complex periodic patterns are common in nature and are observed in physical, chemical and biological systems. Understanding how these patterns are generated in a precise manner is a key challenge. Biological patterns are especially intriguing, as they are generated in a noisy environment; cell position and cell size, for example, are subject to stochastic variations, as are the strengths of the chemical signals mediating cell-to-cell communication. The need to generate a precise and robust pattern in this 'noisy' environment restricts the space of patterning mechanisms that can function in the biological setting. Mathematical modeling is useful in comparing the sensitivity of different mechanisms to such variations, thereby highlighting key aspects of their design.We use mathematical modeling to study the periodic patterning of the fruit fly eye. In this system, a highly ordered lattice of differentiated cells is generated in a two-dimensional cell epithelium. The pattern is first observed by the appearance of evenly spaced clusters of ∼10 cells that express specific genes. Each cluster is subsequently refined into a single cell, which initiates the formation and differentiation of a miniature eye unit, the ommatidium. We formulate a mathematical model based on the known molecular properties of the patterning mechanism, and use a probabilistic approach to calculate the errors in cluster formation and refinement resulting from stochastic cell-to-cell variations ('noise') in different quantitative parameters. This enables us to define the parameters most influencing noise sensitivity. Notably, we find that this error is roughly independent of the desired cluster size, suggesting that large clusters are beneficial for ensuring the overall reproducibility of the periodic cluster arrangement. For the stage of cluster refinement, we find that rapid communication between cells is critical for reducing error. Our work provides new insights into the constraints imposed on mechanisms generating periodic patterning in a realistic, noisy environment, and in particular, discusses the different considerations in achieving optimal design of the patterning network.
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Affiliation(s)
- Avishai Gavish
- Department of Molecular Genetics, Weizmann institute of Science, Rehovot, 76100, Israel.
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel.
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann institute of Science, Rehovot, 76100, Israel
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Gavish A, Shwartz A, Weizman A, Schejter E, Shilo BZ, Barkai N. Periodic patterning of the Drosophila eye is stabilized by the diffusible activator Scabrous. Nat Commun 2016; 7:10461. [PMID: 26876750 PMCID: PMC4756378 DOI: 10.1038/ncomms10461] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Accepted: 12/14/2015] [Indexed: 01/24/2023] Open
Abstract
Generation of periodic patterns is fundamental to the differentiation of multiple tissues during development. How such patterns form robustly is still unclear. The Drosophila eye comprises ∼750 units, whose crystalline order is set during differentiation of the eye imaginal disc: an activation wave sweeping across the disc is coupled to lateral inhibition, sequentially selecting pro-neural cells. Using mathematical modelling, here we show that this template-based lateral inhibition is highly sensitive to spatial variations in biochemical parameters and cell sizes. We reveal the basis of this sensitivity, and suggest that it can be overcome by assuming a short-range diffusible activator. Clonal experiments identify Scabrous, a previously implicated inhibitor, as the predicted activator. Our results reveal the mechanism by which periodic patterning in the fly eye is stabilized against spatial variations, highlighting how the need to maintain robustness shapes the design of patterning circuits. Patterning in the Drosophila eye is achieved by a series of signalling cascades over several cell distances. Here Gavish et al. model lateral inhibition in the developing eye to understand how developmental noise refines such patterning, identifying a novel activator required for buffering spatial variability.
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Affiliation(s)
- Avishai Gavish
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.,Sackler Faculty of Medicine, Geha Mental Health Center, Felsenstein Medical Research Center, Rabin Medical Center, Tel Aviv University, Bellinson Campus, Petah Tiqva 49100, Israel
| | - Arkadi Shwartz
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Abraham Weizman
- Sackler Faculty of Medicine, Geha Mental Health Center, Felsenstein Medical Research Center, Rabin Medical Center, Tel Aviv University, Bellinson Campus, Petah Tiqva 49100, Israel
| | - Eyal Schejter
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Ben-Zion Shilo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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Shilo S, Melamed-Bessudo C, Dorone Y, Barkai N, Levy AA. DNA Crossover Motifs Associated with Epigenetic Modifications Delineate Open Chromatin Regions in Arabidopsis. Plant Cell 2015; 27:2427-36. [PMID: 26381163 PMCID: PMC4815091 DOI: 10.1105/tpc.15.00391] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Accepted: 08/31/2015] [Indexed: 05/14/2023]
Abstract
The rate of crossover, the reciprocal exchanges of homologous chromosomal segments, is not uniform along chromosomes differing between male and female meiocytes. To better understand the factors regulating this variable landscape, we performed a detailed genetic and epigenetic analysis of 737 crossover events in Arabidopsis thaliana. Crossovers were more frequent than expected in promoters. Three DNA motifs enriched in crossover regions and less abundant in crossover-poor pericentric regions were identified. One of these motifs, the CCN repeat, was previously unknown in plants. The A-rich motif was preferentially associated with promoters, while the CCN repeat and the CTT repeat motifs were preferentially associated with genes. Analysis of epigenetic modifications around the motifs showed, in most cases, a specific epigenetic architecture. For example, we show that there is a peak of nucleosome occupancy and of H3K4me3 around the CCN and CTT repeat motifs while nucleosome occupancy was lowest around the A-rich motif. Cytosine methylation levels showed a gradual decrease within ∼2 kb of the three motifs, being lowest at sites where crossover occurred. This landscape was conserved in the decreased DNA methylation1 mutant. In summary, the crossover motifs are associated with epigenetic landscapes corresponding to open chromatin and contributing to the nonuniformity of crossovers in Arabidopsis.
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Affiliation(s)
- Shay Shilo
- Plant and Environmental Sciences Department, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Cathy Melamed-Bessudo
- Plant and Environmental Sciences Department, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yanniv Dorone
- Plant and Environmental Sciences Department, The Weizmann Institute of Science, Rehovot 76100, Israel Département de Biologie, Ecole Normale Supérieure de Lyon, Lyon 69007, France
| | - Naama Barkai
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Avraham A Levy
- Plant and Environmental Sciences Department, The Weizmann Institute of Science, Rehovot 76100, Israel
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47
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Yanagida H, Gispan A, Kadouri N, Rozen S, Sharon M, Barkai N, Tawfik DS. The Evolutionary Potential of Phenotypic Mutations. PLoS Genet 2015; 11:e1005445. [PMID: 26244544 PMCID: PMC4526572 DOI: 10.1371/journal.pgen.1005445] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 07/15/2015] [Indexed: 01/08/2023] Open
Abstract
Errors in protein synthesis, so-called phenotypic mutations, are orders-of-magnitude more frequent than genetic mutations. Here, we provide direct evidence that alternative protein forms and phenotypic variability derived from translational errors paved the path to genetic, evolutionary adaptations via gene duplication. We explored the evolutionary origins of Saccharomyces cerevisiae IDP3 - an NADP-dependent isocitrate dehydrogenase mediating fatty acids ß-oxidation in the peroxisome. Following the yeast whole genome duplication, IDP3 diverged from a cytosolic ancestral gene by acquisition of a C-terminal peroxisomal targeting signal. We discovered that the pre-duplicated cytosolic IDPs are partially localized to the peroxisome owing to +1 translational frameshifts that bypass the stop codon and unveil cryptic peroxisomal targeting signals within the 3’-UTR. Exploring putative cryptic signals in all 3’-UTRs of yeast genomes, we found that other enzymes related to NADPH production such as pyruvate carboxylase 1 (PYC1) might be prone to peroxisomal localization via cryptic signals. Using laboratory evolution we found that these translational frameshifts are rapidly imprinted via genetic single base deletions occurring within the very same gene location. Further, as exemplified here, the sequences that promote translational frameshifts are also more prone to genetic deletions. Thus, genotypes conferring higher phenotypic variability not only meet immediate challenges by unveiling cryptic 3’-UTR sequences, but also boost the potential for future genetic adaptations. The rarity of genetic mutations limits the likelihood of adaptation. However, transcriptional and translational errors, so-called phenotypic mutations, are >105-fold more frequent, thus generating protein mutants from unmodified genes. We provide the first evidence that phenotypic mutations paved the path to what later, after gene duplication, became newly compartmentalized enzymes. Thus, gene duplication followed rather than initiated the divergence of this new trait. Our findings also show that translational infidelity and phenotypic variability comprise the origins of evolutionary innovations, and how selection for enhanced phenotypic variability also promotes the appearance of genetic mutations that lead to the very same outcome.
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Affiliation(s)
- Hayato Yanagida
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Ariel Gispan
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Noam Kadouri
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Shelly Rozen
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Michal Sharon
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Dan S. Tawfik
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
- * E-mail:
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48
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Schmidt-Glenewinkel H, Barkai N. Loss of growth homeostasis by genetic decoupling of cell division from biomass growth: implication for size control mechanisms. Mol Syst Biol 2014; 10:769. [PMID: 25538138 PMCID: PMC4300492 DOI: 10.15252/msb.20145513] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Growing cells adjust their division time with biomass accumulation to maintain growth homeostasis. Size control mechanisms, such as the size checkpoint, provide an inherent coupling of growth and division by gating certain cell cycle transitions based on cell size. We describe genetic manipulations that decouple cell division from cell size, leading to the loss of growth homeostasis, with cells becoming progressively smaller or progressively larger until arresting. This was achieved by modulating glucose influx independently of external glucose. Division rate followed glucose influx, while volume growth was largely defined by external glucose. Therefore, the coordination of size and division observed in wild-type cells reflects tuning of two parallel processes, which is only refined by an inherent feedback-dependent coupling. We present a class of size control models explaining the observed breakdowns of growth homeostasis.
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Affiliation(s)
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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49
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Abstract
Cell size is determined by a complex interplay between growth and division, involving multiple
cellular pathways. To identify systematically processes affecting size control in G1 in budding
yeast, we imaged and analyzed the cell cycle of millions of individual cells representing 591
mutants implicated in size control. Quantitative metric distinguished mutants affecting the
mechanism of size control from the majority of mutants that have a perturbed size due to indirect
effects modulating cell growth. Overall, we identified 17 negative and dozens positive size control
regulators, with the negative regulators forming a small network centered on elements of mitotic
exit network. Some elements of the translation machinery affected size control with a notable
distinction between the deletions of parts of small and large ribosomal subunit: parts of small
ribosomal subunit tended to regulate size control, while parts of the large subunit affected cell
growth. Analysis of small cells revealed additional size control mechanism that functions in G2/M,
complementing the primary size control in G1. Our study provides new insights about size control
mechanisms in budding yeast.
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Affiliation(s)
- Ilya Soifer
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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50
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Vardi N, Levy S, Gurvich Y, Polacheck T, Carmi M, Jaitin D, Amit I, Barkai N. Sequential Feedback Induction Stabilizes the Phosphate Starvation Response in Budding Yeast. Cell Rep 2014; 9:1122-34. [DOI: 10.1016/j.celrep.2014.10.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 09/02/2014] [Accepted: 09/29/2014] [Indexed: 12/14/2022] Open
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