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Cryo-EM structure of chitin synthase
Structural highlights
FunctionCHS1_PHYSP Polymerizes chitin, a structural polymer of the cell wall and septum, by transferring the sugar moiety of UDP-GlcNAc to the non-reducing end of the growing chitin polymer (PubMed:36131020). Involved in mycelial growth, sporangial production, zoospore release and pathogenesis (PubMed:31314944).[1] [2] Publication Abstract from PubMedChitin, an extracellular polysaccharide, is synthesized by membrane-embedded chitin synthase (CHS) utilizing intracellular substrates. The mechanism of the translocation of synthesized chitin across the membrane to extracellular locations remains unresolved. We prove that the chitin synthase from Phytophthora sojae (PsCHS) is a processive glycosyltransferase, which can rapidly produce and tightly bind with the highly polymerized chitin. We further demonstrate that PsCHS is a bifunctional enzyme, which is necessary and sufficient to translocate the synthesized chitin. PsCHS was purified and then reconstituted into proteoliposomes (PLs). The nascent chitin is generated and protected from chitinase degradation unless detergent solubilizes the PLs, showing that PsCHS translocates the newly produced chitin into the lumen of the PLs. We also attempted to resolve the PsCHS structure of the synthesized chitin-bound state, although it was not successful; the obtained high-resolution structure of the UDP/Mn(2+)-bound state could still assist in describing the characterization of the PsCHS's transmembrane channel. Consistently, we demonstrate that PsCHS is indispensable and capable of translocating chitin in a process that is tightly coupled to chitin synthesis. Chitin Translocation Is Functionally Coupled with Synthesis in Chitin Synthase.,Niu S, Qi L, Zhang X, He D, Li P, Wang H, Bi Y Int J Mol Sci. 2024 Oct 30;25(21):11667. doi: 10.3390/ijms252111667. PMID:39519219[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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