biostudies-literatureUnknown16(1)Li JLi Jialu gratefully acknowledges support from the Sichuan Province Innovative Talent Funding Project for Postdoctoral FellowsThe Haihe Laboratory of Sustainable Chemical Transformations for financial supportβ-1,3 Glucan synthase (GS) is essential for fungal cell wall biosynthesis. The GS holoenzyme comprises the glycosyltransferase FKS1 and its regulatory factor Rho1, a small GTPase. However, the mechanism by which Rho1 activates FKS1 in a GTP-dependent manner remains unclear. Here, we present two cryo-EM structures of FKS1, apo and in complex with Rho1. FKS1 adopts a cellulose synthase-like conformation. The interaction between Rho1 and FKS1 is enhanced in the presence of GTPγS. Rho1 is positioned within a pocket between the glycosyltransferase domain of FKS1 (GT domain) and the transmembrane helix spanning TM7-15. Comparison of the two structures reveals extensive conformational changes within FKS1. These alterations suggest that Rho1's GTP/GDP cycling may act as a molecular pump, promotingNature communications2054https://www.ebi.ac.uk/biostudies/studies/S-EPMC11871024biostudies-literatureCryo-EM structure of the β-1,3-glucan synthase FKS1-Rho1 complex.PMC11871024Liu HLi HLiu JLi JZhu ADai XXiao QQian WGuo LDeng DYan CLuo YWang XfalseCryo-EM structure of the β-1,3-glucan synthase FKS1-Rho1 complex.β-1,3 Glucan synthase (GS) is essential for fungal cell wall biosynthesis. The GS holoenzyme comprises the glycosyltransferase FKS1 and its regulatory factor Rho1, a small GTPase. However, the mechanism by which Rho1 activates FKS1 in a GTP-dependent manner remains unclear. Here, we present two cryo-EM structures of FKS1, apo and in complex with Rho1. FKS1 adopts a cellulose synthase-like conformation. The interaction between Rho1 and FKS1 is enhanced in the presence of GTPγS. Rho1 is positioned within a pocket between the glycosyltransferase domain of FKS1 (GT domain) and the transmembrane helix spanning TM7-15. Comparison of the two structures reveals extensive conformational changes within FKS1. These alterations suggest that Rho1's GTP/GDP cycling may act as a molecular pump, promoting2025-01-01T00:00:00Z2025 Feb2026-06-01T08:52:07.547Z2025-04-07T11:28:20.008ZS-EPMC118710244002162910.1038/s41467-025-57152-7