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Jiang XY, Hou F, Shen XD, Du XD, Xu HL, Zou SM. The N-terminal zinc finger domain of Tgf2 transposase contributes to DNA binding and to transposition activity. Sci Rep 2016; 6:27101. [PMID: 27251101 PMCID: PMC4890040 DOI: 10.1038/srep27101] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 05/13/2016] [Indexed: 01/14/2023] Open
Abstract
Active Hobo/Activator/Tam3 (hAT) transposable elements are rarely found in vertebrates. Previously, goldfish Tgf2 was found to be an autonomously active vertebrate transposon that is efficient at gene-transfer in teleost fish. However, little is known about Tgf2 functional domains required for transposition. To explore this, we first predicted in silico a zinc finger domain in the N-terminus of full length Tgf2 transposase (L-Tgf2TPase). Two truncated recombinant Tgf2 transposases with deletions in the N-terminal zinc finger domain, S1- and S2-Tgf2TPase, were expressed in bacteria from goldfish cDNAs. Both truncated Tgf2TPases lost their DNA-binding ability in vitro, specifically at the ends of Tgf2 transposon than native L-Tgf2TPase. Consequently, S1- and S2-Tgf2TPases mediated gene transfer in the zebrafish genome in vivo at a significantly (p < 0.01) lower efficiency (21%–25%), in comparison with L-Tgf2TPase (56% efficiency). Compared to L-Tgf2TPase, truncated Tgf2TPases catalyzed imprecise excisions with partial deletion of TE ends and/or plasmid backbone insertion/deletion. The gene integration into the zebrafish genome mediated by truncated Tgf2TPases was imperfect, creating incomplete 8-bp target site duplications at the insertion sites. These results indicate that the zinc finger domain in Tgf2 transposase is involved in binding to Tgf2 terminal sequences, and loss of those domains has effects on TE transposition.
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Affiliation(s)
- Xia-Yun Jiang
- College of Food Science and Technology, Shanghai Ocean University, Huchenghuan Road 999, Shanghai 201306, China.,Key Laboratory of Freshwater Aquatic Genetic Resources, Shanghai Ocean University, Huchenghuan Road 999, Shanghai 201306, China
| | - Fei Hou
- College of Food Science and Technology, Shanghai Ocean University, Huchenghuan Road 999, Shanghai 201306, China
| | - Xiao-Dan Shen
- Key Laboratory of Freshwater Aquatic Genetic Resources, Shanghai Ocean University, Huchenghuan Road 999, Shanghai 201306, China
| | - Xue-Di Du
- College of animal science and technology, Yangzhou University, Wenhui Road 48, Yangzhou 225009, China
| | - Hai-Li Xu
- College of Food Science and Technology, Shanghai Ocean University, Huchenghuan Road 999, Shanghai 201306, China
| | - Shu-Ming Zou
- Key Laboratory of Freshwater Aquatic Genetic Resources, Shanghai Ocean University, Huchenghuan Road 999, Shanghai 201306, China
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Abstract
hAT transposons are ancient in their origin and they are widespread across eukaryote kingdoms. They can be present in large numbers in many genomes. However, only a few active forms of these elements have so far been discovered indicating that, like all transposable elements, there is selective pressure to inactivate them. Nonetheless, there have been sufficient numbers of active hAT elements and their transposases characterized that permit an analysis of their structure and function. This review analyzes these and provides a comparison with the several domesticated hAT genes discovered in eukaryote genomes. Active hAT transposons have also been developed as genetic tools and understanding how these may be optimally utilized in new hosts will depend, in part, on understanding the basis of their function in genomes.
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Hickman AB, Ewis HE, Li X, Knapp JA, Laver T, Doss AL, Tolun G, Steven AC, Grishaev A, Bax A, Atkinson PW, Craig NL, Dyda F. Structural basis of hAT transposon end recognition by Hermes, an octameric DNA transposase from Musca domestica. Cell 2014; 158:353-367. [PMID: 25036632 DOI: 10.1016/j.cell.2014.05.037] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 04/10/2014] [Accepted: 05/12/2014] [Indexed: 11/25/2022]
Abstract
Hermes is a member of the hAT transposon superfamily that has active representatives, including McClintock's archetypal Ac mobile genetic element, in many eukaryotic species. The crystal structure of the Hermes transposase-DNA complex reveals that Hermes forms an octameric ring organized as a tetramer of dimers. Although isolated dimers are active in vitro for all the chemical steps of transposition, only octamers are active in vivo. The octamer can provide not only multiple specific DNA-binding domains to recognize repeated subterminal sequences within the transposon ends, which are important for activity, but also multiple nonspecific DNA binding surfaces for target capture. The unusual assembly explains the basis of bipartite DNA recognition at hAT transposon ends, provides a rationale for transposon end asymmetry, and suggests how the avidity provided by multiple sites of interaction could allow a transposase to locate its transposon ends amidst a sea of chromosomal DNA.
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Affiliation(s)
- Alison B Hickman
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hosam E Ewis
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Xianghong Li
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Joshua A Knapp
- Graduate Program in Biochemistry and Molecular Biology, University of California Riverside, Riverside, CA 92521, USA
| | - Thomas Laver
- Graduate Program in Genetics, Genomics, and Bioinformatics, University of California Riverside, Riverside, CA 92521, USA
| | - Anna-Louise Doss
- Graduate Program in Cell, Molecular, and Developmental Biology, University of California Riverside, Riverside, CA 92521, USA
| | - Gökhan Tolun
- Laboratory of Structural Biology Research, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alasdair C Steven
- Laboratory of Structural Biology Research, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alexander Grishaev
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ad Bax
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Peter W Atkinson
- Graduate Program in Biochemistry and Molecular Biology, University of California Riverside, Riverside, CA 92521, USA; Graduate Program in Genetics, Genomics, and Bioinformatics, University of California Riverside, Riverside, CA 92521, USA; Graduate Program in Cell, Molecular, and Developmental Biology, University of California Riverside, Riverside, CA 92521, USA; Department of Entomology and Institute for Integrative Genome Biology, University of California Riverside, Riverside, CA 92521, USA
| | - Nancy L Craig
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Fred Dyda
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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