{"id":35350,"date":"2020-07-27T20:17:00","date_gmt":"2020-07-27T17:17:00","guid":{"rendered":"https:\/\/en.buradabiliyorum.com\/researchers-develop-new-cytosine-base-editors-with-high-specificity-and-precision\/"},"modified":"2020-07-27T20:17:00","modified_gmt":"2020-07-27T17:17:00","slug":"researchers-develop-new-cytosine-base-editors-with-high-specificity-and-precision","status":"publish","type":"post","link":"https:\/\/buradabiliyorum.com\/en\/researchers-develop-new-cytosine-base-editors-with-high-specificity-and-precision\/","title":{"rendered":"#Researchers develop new cytosine base editors with high specificity and precision"},"content":{"rendered":"

“#Researchers develop new cytosine base editors with high specificity and precision<\/strong>”<\/p>\n

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\"Researchers<\/img>
\n Top: Rationally-designed APOBEC3B deaminases. Middle: Evaluation of the specificity of CBEs by the orthogonal R-loop assay. Bottom: Evaluation of the specificity of CBEs by whole genome sequencing. Credit: IGDB
\n <\/figcaption><\/figure>\n<\/div>\n<\/div>\n

Base editors, which enable production of highly efficient targeted point mutations in genomic DNA without causing double-stranded DNA breaks, hold great promise for gene therapy in human disease and trait improvement in crop plants.<\/p>\n

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Gao Caixia’s group from the Institute of Genetics and Developmental Biology of the Chinese Academy of Science<\/a>s has been developing plant base editing technologies. The researchers showed that cytosine base editors (CBEs) induce unexpected genome-wide off-target mutations in rice in order to stimulate the worldwide genome editing community to correct them.<\/p>\n

Recently, GAO’s team created two new CBEs based on a truncated human APOBEC3 cytidine deaminase (A3Bctd) and developed a high-throughput assay for assessing sgRNA-independent deamination changes in plant CBEs.
\nThey first developed a rapid, high-throughput and inexpensive method for assessing CBEs in plants (nSaCas9-media<\/a>ted orthogonal R-loop assay). In this assay, the orthogonal CRISPR system, nSaCas9, was used to create ssDNA regions in plant cells that acted as targets for sgRNA-independent deamination changes. To assess the nSaCas9-mediated orthogonal R-loop assay, they compared it with the whole-genome sequencing (WGS) assay.
\nThe consistent results indicate that the nSaCas9-mediated orthogonal R-loop assay provides a logical, rapid and high-throughput method for assessing the sgRNA-independent off-target activities of CBEs.
\nThen they created 16 A3Bctd deaminase variants by rational design and evaluated their on-target efficiency and the sgRNA-independent off-target activities. They tested these A3Bctd-BE3 variants using the R-loop assay and selected seven mutations associated with efficient on-target editing activity and reduced off-target activity. After that, they combined these mutations and produced nine new A3Bctd-BE3 variants with double or trip<\/a>le amino acid substitutions.
\nIn this way, they obtained two new CBE variants, A3Bctd-VHM-BE3 and A3Bctd-KKR-BE3, which exhibited efficient on-target activity and markedly reduced sgRNA-independent off-target activity.
\nIn addition, these two new CBEs behaved more precisely at their target sites, and mainly produced single and double C edits. Also, they validated the high specificity of A3Bctd-VHM-BE3 and A3Bctd-KKR-BE3 by WGS assay.
\nThe scientific paper, entitled “Rationally designed APOBEC3B cytosine base editors with improved specificity,” was online published in Molecular Cell<\/i> on July 27.
\nThe research was mainly supported by the National Transgenic Science and Technology<\/a> Program, the Strategic Priority Research Program of the Chinese Academy of Sciences, and the National Natural Science Foundation of China.<\/p>\n

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More information:<\/strong>
\n Shuai Jin et al. Rationally Designed APOBEC3B Cytosine Base Editors with Improved Specificity, Molecular Cell<\/i> (2020). DOI: 10.1016\/j.molcel.2020.07.005<\/p>\n

\n Citation<\/strong>:
\n Researchers develop new cytosine base editors with high specificity and precision (2020, July 27)
\n retrieved 27 July 2020
\n from https:\/\/phys.org\/news<\/a>\/2020-07-cytosine-base-editors-high-specificity.html<\/p>\n

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“#Researchers develop new cytosine base editors with high specificity and precision” Top: Rationally-designed APOBEC3B deaminases. Middle: Evaluation of the specificity of CBEs by the orthogonal R-loop assay. Bottom: Evaluation of the specificity of CBEs by whole genome sequencing. Credit: IGDB Base editors, which enable production of highly efficient targeted point mutations in genomic DNA without…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"fifu_image_url":"","fifu_image_alt":"","footnotes":""},"categories":[16],"tags":[10663,44856],"class_list":["post-35350","post","type-post","status-publish","format-standard","hentry","category-sciencee","tag-biotechnology-molecular-computational-biology","tag-researchers-develop-new-cytosine-base-editors-with-high-specificity-and-precision"],"_links":{"self":[{"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/posts\/35350","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/comments?post=35350"}],"version-history":[{"count":0,"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/posts\/35350\/revisions"}],"wp:attachment":[{"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/media?parent=35350"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/categories?post=35350"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/tags?post=35350"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}