The mechanism of thioamide formation by the YcfA-YcfC system in 6-thioguanine biosynthesis

Li Zhang, Chao Dou, Weizhu Yan, Pengpeng Chen, Xinyu Jia, Na Zhang, Dan Zhou, Zhaolin Long, Lu Zhang, Xiaofeng Zhu () and Wei Cheng ()
Additional contact information
Li Zhang: Sichuan University
Chao Dou: Chengdu University
Weizhu Yan: Sichuan University
Pengpeng Chen: Sichuan University
Xinyu Jia: Sichuan University
Na Zhang: Sichuan University
Dan Zhou: Sichuan University
Zhaolin Long: Sichuan University
Lu Zhang: Sichuan University
Xiaofeng Zhu: Sichuan University
Wei Cheng: Sichuan University

Nature Communications, 2025, vol. 16, issue 1, 1-15

Abstract: Abstract 6-thioguanine (6-TG) is a therapeutic medication for childhood acute lymphoblastic leukemia (ALL) and a potent antimicrobial agent. Its biosynthesis relies on the YcfA-YcfC system, yet the formation of its critical thioamide moiety remains incompletely understood. Here, we provide a detailed biochemical and structural characterization of YcfA, including apo and substrate-bound crystal structures, which reveal that substrate adenylation and L-cysteine addition are key initial steps in the reaction cascade. Cryo-electron microscopy (cryo-EM) and functional analyses highlight YcfA’s assembly into a two-layered heptameric structure, essential for the enzymatic function. GTP serves a dual role as a substrate and oligomerization enhancer. Additionally, pyridoxal 5’-phosphate (PLP), a cofactor for YcfC, the partner enzyme in this system, promotes YcfA oligomerization but inhibits its activity by obstructing GTP binding. Biochemical and structural evidence confirms that YcfC acts as a C‒S lyase, which is essential for thioamide formation in the presence of PLP. Exploiting substrate flexibility, we synthesized a seleno analog with antimicrobial properties. Multi-omics analyses of the biosynthetic precursor underscore its potential as an antibiotic. Collectively, our findings unravel the distinct architecture and functionality of the YcfA-YcfC system, offering an evolutionary perspective on noncanonical thioamide biosynthesis and a foundation for synthetic biology applications in drug development.

Date: 2025
References: Add references at CitEc
Citations:

Downloads: (external link)
https://www.nature.com/articles/s41467-025-63937-7 Abstract (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:nat:natcom:v:16:y:2025:i:1:d:10.1038_s41467-025-63937-7

Ordering information: This journal article can be ordered from
https://www.nature.com/ncomms/

DOI: 10.1038/s41467-025-63937-7

Access Statistics for this article

Nature Communications is currently edited by Nathalie Le Bot, Enda Bergin and Fiona Gillespie

More articles in Nature Communications from Nature
Bibliographic data for series maintained by Sonal Shukla () and Springer Nature Abstracting and Indexing ().