@article{2a8e6ecffca84999b3049af832923e2e,
title = "Horizontal Transfer of Bacterial Cytolethal Distending Toxin B Genes to Insects",
abstract = "Horizontal gene transfer events have played a major role in the evolution of microbial species, but their importance in animals is less clear. Here, we report horizontal gene transfer of cytolethal distending toxin B (cdtB), prokaryotic genes encoding eukaryote-targeting DNase I toxins, into the genomes of vinegar flies (Diptera: Drosophilidae) and aphids (Hemiptera: Aphididae). We found insect-encoded cdtB genes are most closely related to orthologs from bacteriophage that infect Candidatus Hamiltonella defensa, a bacterial mutualistic symbiont of aphids that confers resistance to parasitoid wasps. In drosophilids, cdtB orthologs are highly expressed during the parasitoid-prone larval stage and encode a protein with ancestral DNase activity. We show that cdtB has been domesticated by diverse insects and hypothesize that it functions in defense against their natural enemies.",
keywords = "Aphids, Cytolethal distending toxin, DNase, Drosophila, Horizontal gene transfer",
author = "Verster, {Kirsten I.} and Wisecaver, {Jennifer H.} and Marianthi Karageorgi and Duncan, {Rebecca P.} and Gloss, {Andrew D.} and Armstrong, {Ellie E.} and Price, {Donald K.} and Menon, {Aruna R.} and Ali, {Zainab M.} and Whiteman, {Noah K.} and Harmit Malik",
note = "Funding Information: We thank Dr Chris Jeans and Brooks Bond-Watts for their preparation of purified CdtB. Coco Verster provided field assistance in acquiring specimens. Raoul O. Martin provided biochemistry advice, Dr Stefan Prost and Timothy O{\textquoteright}Connor provided bioinformatics advice, Julianne N. Pelaez assisted in phylogenetic reconstruction, and Dr Anthony T. Iavarone performed mass spectrometry analysis. Dr Artyom Kopp and Dr Doris Bachtrog provided Drosophila specimens. The M. persicae transcriptome assembly was provided by Dr Alex Wilson and Dr Honglin Feng. Dr Nancy Moran ran BLAST searches of unpublished aphid genomes that corroborated our conclusions from this study. Dr Naomi E. Pierce and Dr Frederick M. Ausubel provided early support for obtaining a genome sequence from S. flava. Funding: K.I.V. was supported by a National Science Foundation Graduate Research Fellowship and grants from Sigma Xi (University of California – Berkeley chapter) and the Animal Behavior Society. R.P.D. was supported by the Miller Institute for Basic Research in Science at the University of California, Berkeley. Research was supported by the National Institute of General Medical Science of the National Institutes of Health award number R35GM119816 to N.K.W. K.I.V., A.D.G., and N.K.W. are inventors on a preliminary patent application related to this work, entitled “Cytolethal distending toxin B from insects for human cancer treatment.” Publisher Copyright: {\textcopyright} 2019 The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved.",
year = "2019",
month = oct,
day = "1",
doi = "10.1093/molbev/msz146",
language = "English (US)",
volume = "36",
pages = "2105--2110",
journal = "Molecular Biology and Evolution",
issn = "0737-4038",
publisher = "Oxford University Press",
number = "10",
}