1
|
Rugbjerg P, Genee HJ, Jensen K, Sarup-Lytzen K, Sommer MOA. Molecular Buffers Permit Sensitivity Tuning and Inversion of Riboswitch Signals. ACS Synth Biol 2016; 5:632-8. [PMID: 27138234 PMCID: PMC4949582 DOI: 10.1021/acssynbio.5b00213] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Predictable integration
of foreign biological signals and parts
remains a key challenge in the systematic engineering of synthetic
cellular actuations, and general methods to improve signal transduction
and sensitivity are needed. To address this problem we modeled and
built a molecular signal buffer network in Saccharomyces cerevisiae inspired by chemical pH buffer systems. The molecular buffer system
context-insulates a riboswitch enabling synthetic control of colony
formation and modular signal manipulations. The riboswitch signal
is relayed to a transcriptional activation domain of a split transcription
factor, while interacting DNA-binding domains mediate the transduction
of signal and form an interacting molecular buffer. The molecular
buffer system enables modular signal inversion through integration
with repressor modules. Further, tuning of input sensitivity was achieved
through perturbation of the buffer pair ratio guided by a mathematical
model. Such buffered signal tuning networks will be useful for domestication
of RNA-based sensors enabling tunable outputs and library-wide selections
for drug discovery and metabolic engineering.
Collapse
Affiliation(s)
- Peter Rugbjerg
- Novo Nordisk Foundation Center
for Biosustainability, Technical University of Denmark, Kogle Allé
6, DK-2970 Hørsholm, Denmark
| | - Hans Jasper Genee
- Novo Nordisk Foundation Center
for Biosustainability, Technical University of Denmark, Kogle Allé
6, DK-2970 Hørsholm, Denmark
| | - Kristian Jensen
- Novo Nordisk Foundation Center
for Biosustainability, Technical University of Denmark, Kogle Allé
6, DK-2970 Hørsholm, Denmark
| | - Kira Sarup-Lytzen
- Novo Nordisk Foundation Center
for Biosustainability, Technical University of Denmark, Kogle Allé
6, DK-2970 Hørsholm, Denmark
| | - Morten Otto Alexander Sommer
- Novo Nordisk Foundation Center
for Biosustainability, Technical University of Denmark, Kogle Allé
6, DK-2970 Hørsholm, Denmark
| |
Collapse
|
2
|
Ball LG, Hanna MD, Lambrecht AD, Mitchell BA, Ziola B, Cobb JA, Xiao W. The Mre11-Rad50-Xrs2 complex is required for yeast DNA postreplication repair. PLoS One 2014; 9:e109292. [PMID: 25343618 PMCID: PMC4208732 DOI: 10.1371/journal.pone.0109292] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2013] [Accepted: 09/10/2014] [Indexed: 12/17/2022] Open
Abstract
Yeast DNA postreplication repair (PRR) bypasses replication-blocking lesions to prevent damage-induced cell death. PRR employs two different mechanisms to bypass damaged DNA, namely translesion synthesis (TLS) and error-free PRR, which are regulated via sequential ubiquitination of proliferating cell nuclear antigen (PCNA). We previously demonstrated that error-free PRR utilizes homologous recombination to facilitate template switching. To our surprise, genes encoding the Mre11-Rad50-Xrs2 (MRX) complex, which are also required for homologous recombination, are epistatic to TLS mutations. Further genetic analyses indicated that two other nucleases involved in double-strand end resection, Sae2 and Exo1, are also variably required for efficient lesion bypass. The involvement of the above genes in TLS and/or error-free PRR could be distinguished by the mutagenesis assay and their differential effects on PCNA ubiquitination. Consistent with the observation that the MRX complex is required for both branches of PRR, the MRX complex was found to physically interact with Rad18 in vivo. In light of the distinct and overlapping activities of the above nucleases in the resection of double-strand breaks, we propose that the interplay between distinct single-strand nucleases dictate the preference between TLS and error-free PRR for lesion bypass.
Collapse
Affiliation(s)
- Lindsay G. Ball
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK, Canada
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada
| | - Michelle D. Hanna
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Amanda D. Lambrecht
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Bryan A. Mitchell
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Barry Ziola
- Department of Pathology and Laboratory Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Jennifer A. Cobb
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada
| | - Wei Xiao
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK, Canada
- College of Life Sciences, Capital Normal University, Beijing, China
- * E-mail:
| |
Collapse
|
3
|
Stevens JR, O'Donnell AF, Perry TE, Benjamin JJR, Barnes CA, Johnston GC, Singer RA. FACT, the Bur kinase pathway, and the histone co-repressor HirC have overlapping nucleosome-related roles in yeast transcription elongation. PLoS One 2011; 6:e25644. [PMID: 22022426 PMCID: PMC3192111 DOI: 10.1371/journal.pone.0025644] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 09/06/2011] [Indexed: 02/03/2023] Open
Abstract
Gene transcription is constrained by the nucleosomal nature of chromosomal DNA. This nucleosomal barrier is modulated by FACT, a conserved histone-binding heterodimer. FACT mediates transcription-linked nucleosome disassembly and also nucleosome reassembly in the wake of the RNA polymerase II transcription complex, and in this way maintains the repression of ‘cryptic’ promoters found within some genes. Here we focus on a novel mutant version of the yeast FACT subunit Spt16 that supplies essential Spt16 activities but impairs transcription-linked nucleosome reassembly in dominant fashion. This Spt16 mutant protein also has genetic effects that are recessive, which we used to show that certain Spt16 activities collaborate with histone acetylation and the activities of a Bur-kinase/Spt4–Spt5/Paf1C pathway that facilitate transcription elongation. These collaborating activities were opposed by the actions of Rpd3S, a histone deacetylase that restores a repressive chromatin environment in a transcription-linked manner. Spt16 activity paralleling that of HirC, a co-repressor of histone gene expression, was also found to be opposed by Rpd3S. Our findings suggest that Spt16, the Bur/Spt4–Spt5/Paf1C pathway, and normal histone abundance and/or stoichiometry, in mutually cooperative fashion, facilitate nucleosome disassembly during transcription elongation. The recessive nature of these effects of the mutant Spt16 protein on transcription-linked nucleosome disassembly, contrasted to its dominant negative effect on transcription-linked nucleosome reassembly, indicate that mutant FACT harbouring the mutant Spt16 protein competes poorly with normal FACT at the stage of transcription-linked nucleosome disassembly, but effectively with normal FACT for transcription-linked nucleosome reassembly. This functional difference is consistent with the idea that FACT association with the transcription elongation complex depends on nucleosome disassembly, and that the same FACT molecule that associates with an elongation complex through nucleosome disassembly is retained for reassembly of the same nucleosome.
Collapse
Affiliation(s)
- Jennifer R. Stevens
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Allyson F. O'Donnell
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Troy E. Perry
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Jeremy J. R. Benjamin
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Christine A. Barnes
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Gerald C. Johnston
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Richard A. Singer
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- * E-mail:
| |
Collapse
|
4
|
Barbour L, Ball LG, Zhang K, Xiao W. DNA damage checkpoints are involved in postreplication repair. Genetics 2006; 174:1789-800. [PMID: 17057245 PMCID: PMC1698651 DOI: 10.1534/genetics.106.056283] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2006] [Accepted: 10/10/2006] [Indexed: 11/18/2022] Open
Abstract
Saccharomyces cerevisiae MMS2 encodes a ubiquitin-conjugating enzyme variant, belongs to the error-free branch of the RAD6 postreplication repair (PRR) pathway, and is parallel to the REV3-mediated mutagenesis branch. A mutation in genes of either the MMS2 or the REV3 branch does not result in extreme sensitivity to DNA-damaging agents; however, deletion of both subpathways of PRR results in a synergistic phenotype. Nevertheless, the double mutant is not as sensitive to DNA-damaging agents as a rad6 or rad18 mutant defective in the entire PRR pathway, suggesting the presence of an additional subpathway within PRR. A synthetic lethal screen was employed in the presence of a sublethal dose of a DNA-damaging agent to identify novel genes involved in PRR, which resulted in the isolation of RAD9 as a candidate PRR gene. Epistatic analysis showed that rad9 is synergistic to both mms2 and rev3 with respect to killing by methyl methanesulfonate (MMS), and the triple mutant is nearly as sensitive as the rad18 single mutant. In addition, rad9 rad18 is no more sensitive to MMS than the rad18 single mutant, suggesting that rad9 plays a role within the PRR pathway. Moreover, deletion of RAD9 reduces damage-induced mutagenesis and the mms2 spontaneous and induced mutagenesis is partially dependent on the RAD9 gene. We further demonstrated that the observed synergistic interactions apply to any two members between different branches of PRR and G1/S and G2/M checkpoint genes. These results suggest that a damage checkpoint is essential for tolerance mediated by both the error-free and error-prone branches of PRR.
Collapse
Affiliation(s)
- Leslie Barbour
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | | | | | | |
Collapse
|
5
|
Barbour L, Xiao W. Mating type regulation of cellular tolerance to DNA damage is specific to the DNA post-replication repair and mutagenesis pathway. Mol Microbiol 2006; 59:637-50. [PMID: 16390456 DOI: 10.1111/j.1365-2958.2005.04965.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In order to help further define DNA post-replication repair (PRR), a conditional synthetic lethal screen was employed to identify new genes involved in the PRR pathway. A synthetic lethal screen with the mms2 mutation resulted in the recovery of two suppressor mutations responsible for regulating PRR. The recovered suppressors are the mating type genes and SIR3. Indeed, controlled expression of both mating type genes or deletion of SIR3 rescued the conditional synthetic lethal mutant phenotypes. Furthermore, comprehensive analyses suggest that mating type heterozygosity confers tolerance to a broad range of DNA damage, and that this effect is limited to all PRR pathway mutations, but does not apply to base excision repair, nucleotide excision repair or recombination repair mutants. In addition, the tolerance conferred to PRR mutants as a result of mating type heterozygosity is dependent on a functional homologous recombination but not the non-homologous end-joining pathway. Thus, mating type status appears to be responsible for signalling DNA content and possibly cell cycle stage, allowing the cell to select the most efficient means to repair the DNA damage.
Collapse
Affiliation(s)
- Leslie Barbour
- Department of Microbiology and Immunology, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, Canada S7N 5E5
| | | |
Collapse
|
6
|
|