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Andersen KR. Insights into Rad3 kinase recruitment from the crystal structure of the DNA damage checkpoint protein Rad26. J Biol Chem 2017; 292:8149-8157. [PMID: 28314775 DOI: 10.1074/jbc.m117.780189] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 03/14/2017] [Indexed: 12/30/2022] Open
Abstract
Metabolic products and environmental factors constantly damage DNA. To protect against these insults and maintain genome integrity, cells have evolved mechanisms to repair DNA lesions. One such mechanism involves Rad3, a master kinase coordinating the DNA damage response. Rad26 is a functional subunit of the Rad3-Rad26 complex and is responsible for bringing the kinase to sites of DNA damage. Here, I present the crystal structure of Rad26 and identify the elements important for recruiting Rad3. The structure suggests that Rad26 is a dimer with a conserved interface in the N-terminal part of the protein. Biochemical data showed that Rad26 uses its C-terminal domain and the flanking kinase-docking motif to bind specific HEAT repeats in Rad3. Analysis of the reconstituted Rad3-Rad26 heterotetrameric complex with electron microscopy enabled me to propose a structural model for its quaternary structure. In conclusion, these results suggest that Rad26 exists as a dimer and provide crucial insight into how Rad3 is recruited and incorporated into the Rad3-Rad26 DNA repair complex.
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Eltschinger S, Loewith R. TOR Complexes and the Maintenance of Cellular Homeostasis. Trends Cell Biol 2015; 26:148-159. [PMID: 26546292 DOI: 10.1016/j.tcb.2015.10.003] [Citation(s) in RCA: 131] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 09/29/2015] [Accepted: 10/01/2015] [Indexed: 12/30/2022]
Abstract
The Target of Rapamycin (TOR) is a conserved serine/threonine (ser/thr) kinase that functions in two, distinct, multiprotein complexes called TORC1 and TORC2. Each complex regulates different aspects of eukaryote growth: TORC1 regulates cell volume and/or mass by influencing protein synthesis and turnover, while TORC2, as detailed in this review, regulates cell surface area by influencing lipid production and intracellular turgor. TOR complexes function in feedback loops, implying that downstream effectors are also likely to be involved in upstream regulation. In this regard, the notion that TORCs function primarily as mediators of cellular and organismal homeostasis is fundamentally different from the current, predominate view of TOR as a direct transducer of extracellular biotic and abiotic signals.
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Affiliation(s)
- Sandra Eltschinger
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland; iGE3 Institute of Genetics and Genomics of Geneva, Geneva, Switzerland
| | - Robbie Loewith
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland; iGE3 Institute of Genetics and Genomics of Geneva, Geneva, Switzerland; National Centre for Competence in Research in Chemical Biology, Geneva, Switzerland.
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Oliveira AP, Dimopoulos S, Busetto AG, Christen S, Dechant R, Falter L, Haghir Chehreghani M, Jozefczuk S, Ludwig C, Rudroff F, Schulz JC, González A, Soulard A, Stracka D, Aebersold R, Buhmann JM, Hall MN, Peter M, Sauer U, Stelling J. Inferring causal metabolic signals that regulate the dynamic TORC1-dependent transcriptome. Mol Syst Biol 2015; 11:802. [PMID: 25888284 PMCID: PMC4422559 DOI: 10.15252/msb.20145475] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cells react to nutritional cues in changing environments via the integrated action of signaling, transcriptional, and metabolic networks. Mechanistic insight into signaling processes is often complicated because ubiquitous feedback loops obscure causal relationships. Consequently, the endogenous inputs of many nutrient signaling pathways remain unknown. Recent advances for system-wide experimental data generation have facilitated the quantification of signaling systems, but the integration of multi-level dynamic data remains challenging. Here, we co-designed dynamic experiments and a probabilistic, model-based method to infer causal relationships between metabolism, signaling, and gene regulation. We analyzed the dynamic regulation of nitrogen metabolism by the target of rapamycin complex 1 (TORC1) pathway in budding yeast. Dynamic transcriptomic, proteomic, and metabolomic measurements along shifts in nitrogen quality yielded a consistent dataset that demonstrated extensive re-wiring of cellular networks during adaptation. Our inference method identified putative downstream targets of TORC1 and putative metabolic inputs of TORC1, including the hypothesized glutamine signal. The work provides a basis for further mechanistic studies of nitrogen metabolism and a general computational framework to study cellular processes.
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Affiliation(s)
- Ana Paula Oliveira
- Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland
| | - Sotiris Dimopoulos
- Department of Biosystems Science and Engineering and SIB Swiss Institute of Bioinformatics, ETH Zurich, Basel, Switzerland
| | | | - Stefan Christen
- Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland
| | - Reinhard Dechant
- Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Laura Falter
- Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland
| | | | - Szymon Jozefczuk
- Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland
| | - Christina Ludwig
- Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland
| | - Florian Rudroff
- Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland
| | - Juliane Caroline Schulz
- Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland
| | | | - Alexandre Soulard
- Biozentrum, University of Basel, Basel, Switzerland UMR5240 MAP, Université Lyon 1, Villeurbanne, France
| | | | - Ruedi Aebersold
- Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland Faculty of Science, University of Zurich, Zurich, Switzerland
| | | | | | - Matthias Peter
- Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Uwe Sauer
- Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland
| | - Jörg Stelling
- Department of Biosystems Science and Engineering and SIB Swiss Institute of Bioinformatics, ETH Zurich, Basel, Switzerland
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Dhara A, Eum JH, Robertson A, Gulia-Nuss M, Vogel KJ, Clark KD, Graf R, Brown MR, Strand MR. Ovary ecdysteroidogenic hormone functions independently of the insulin receptor in the yellow fever mosquito, Aedes aegypti. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:1100-8. [PMID: 24076067 PMCID: PMC3885182 DOI: 10.1016/j.ibmb.2013.09.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Revised: 09/18/2013] [Accepted: 09/18/2013] [Indexed: 05/11/2023]
Abstract
Most mosquito species must feed on the blood of a vertebrate host to produce eggs. In the yellow fever mosquito, Aedes aegypti, blood feeding triggers medial neurosecretory cells in the brain to release insulin-like peptides (ILPs) and ovary ecdysteroidogenic hormone (OEH). Theses hormones thereafter directly induce the ovaries to produce ecdysteroid hormone (ECD), which activates the synthesis of yolk proteins in the fat body for uptake by oocytes. ILP3 stimulates ECD production by binding to the mosquito insulin receptor (MIR). In contrast, little is known about the mode of action of OEH, which is a member of a neuropeptide family called neuroparsin. Here we report that OEH is the only neuroparsin family member present in the Ae. aegypti genome and that other mosquitoes also encode only one neuroparsin gene. Immunoblotting experiments suggested that the full-length form of the peptide, which we call long OEH (lOEH), is processed into short OEH (sOEH). The importance of processing, however, remained unclear because a recombinant form of lOEH (rlOEH) and synthetic sOEH exhibited very similar biological activity. A series of experiments indicated that neither rlOEH nor sOEH bound to ILP3 or the MIR. Signaling studies further showed that ILP3 activated the MIR but rlOEH did not, yet both neuropeptides activated Akt, which is a marker for insulin pathway signaling. Our results also indicated that activation of TOR signaling in the ovaries required co-stimulation by amino acids and either ILP3 or rlOEH. Overall, we conclude that OEH activates the insulin signaling pathway independently of the MIR, and that insulin and TOR signaling in the ovaries is coupled.
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Affiliation(s)
- Animesh Dhara
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Jai-Hoon Eum
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
| | - Anne Robertson
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
| | - Monika Gulia-Nuss
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
- Department of Entomology, Purdue University, West Lafayette, IN 47907, USA
| | - Kevin J. Vogel
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
| | | | - Rolf Graf
- Pancreatitis Research Laboratory DL 34, Rämistrasse 100, Universitätsspital Zürich, 8091 Zürich, Switzerland
| | - Mark R. Brown
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
- Corresponding authors: Tel.: 706-542-2816; fax: 706-542-2279, (M. R. Brown), (M. R. Strand)
| | - Michael R. Strand
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
- Corresponding authors: Tel.: 706-542-2816; fax: 706-542-2279, (M. R. Brown), (M. R. Strand)
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