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Yong E. Zhang @pkuzhangy.bsky.social · 5d

Many thanks, Cedric!

Yong E. Zhang @pkuzhangy.bsky.social · 7d

8/8 I appreciate that Caixia invited me to join this exciting scentific journey. This discovery was only possible through a team effort. Huge thanks and congrautulations to all collaborators!

Yong E. Zhang @pkuzhangy.bsky.social · 7d

7/8 Studying TranCs mirrors the classical framework of studying new gene origins: identify recent transitions, compare ancestral and derived states, infer key steps.

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Yong E. Zhang @pkuzhangy.bsky.social · 7d

6/8 Why did Cas12 evolve repeatedly, while Cas9/Cas13 seemingly arose only once? We discuss that the huge diversity of TnpB transposons & the high evolvability of RNA created the perfect storm for recurrent origins, a potential case of molecular contingency.

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Yong E. Zhang @pkuzhangy.bsky.social · 7d

5/8 We engineered this transition: by artificially splitting ISDra2 TnpB’s reRNA into tracrRNA and crRNA, we converted it into a functional CRISPR-like system. This confirms RNA splitting was a key step in Cas12 emergence.

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Yong E. Zhang @pkuzhangy.bsky.social · 7d

4/8 Cryo-EM shows TranC (LaTranC) protein is structurally similar to its TnpB ancestor. The key innovation was at the RNA level: the guide reRNA functionally split into a tracrRNA & crRNA. Computional analysis indicate it as a convergent event across TranC clades.

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Yong E. Zhang @pkuzhangy.bsky.social · 7d

3/8 These TranCs (e.g., LaTranC) are true intermediates: they can be guided by both CRISPR crRNAs AND transposon-derived reRNAs! This dual-guide capacity shows they retain ancestral TnpB function while acquiring CRISPR immunity.

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Yong E. Zhang @pkuzhangy.bsky.social · 7d

2/8 Phylogenetic mining revealed several young Cas12 clades we call “TranCs”, i.e., nascent CRISPR systems emerging from distinct TnpB lineages. These represent multiple independent domestication events from transposons.

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Yong E. Zhang @pkuzhangy.bsky.social · 7d

1/8 Our new paper w/ Drs. Caixia Gao & Gogo Liu groups reveals how #CRISPR-Cas12 systems evolved from transposon-encoded TnpB nucleases through RNA splitting by analyzing “TranC” systems (evolutionary intermediates bridging selfish elements and adaptive immunity). #Evolution

Cell - a Cell Press journal @cp-cell.bsky.social · 8d

Now online! Functional RNA splitting drove the evolutionary emergence of type V CRISPR-Cas systems from transposons

Functional RNA splitting drove the evolutionary emergence of type V CRISPR-Cas systems from transposons

Identification of TranC systems reveals evolutionary intermediates bridging from transposon-encoded TnpBs and CRISPR-Cas12 effectors. Evolutionary, structural, and functional analyses show that RNA splitting into tracrRNA and crRNA was a pivotal step in the emergence of type V CRISPR systems.

dlvr.it

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Reposted by Yong E. Zhang

Jinfeng Chen @jinfeng7chen.bsky.social · Dec 23

SMBE 2025 (July 20-24 in Beijing, China) is now open for abstract submission. We have a symposium for TE folks: Transposable Elements in Genome Evolution and Biotechnology Development. Please spread the message and submit your abstract. See you in Beijing.

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Reposted by Yong E. Zhang

Li Zhao @lizhao.bsky.social · Jan 22

Abstract submission for SMBE2025 in Beijing is open. If you study gene duplication or new genes, please consider submitting an abstract for a talk for Symposium 7, The Origin, Evolution, and Phenotypic Contributions of New Genes. smbe2025.scimeeting.cn/en/web/index.... Deadline is Jan 30, 2025.

SMBE 2025 - Annual Meeting of the Society for Molecular Biology & Evolution, 2025

2025年国际分子与生物进化，在线会议，会议直播平台，网络会议直播，美迪康会务通，学术会议管理系统，会议活动管理，注册签到管理，会场幻灯片传输转播，PPT传输，会议网络直播，电子壁报管理系统，医学会，会员管理系统

smbe2025.scimeeting.cn

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