Fig. 1

Novel fold of Rift Valley fever virus Gn glycoprotein. a The domain organisation of the M-segment of RVFV showing the domain organisation of Gn and Gc by colour. Domain A is teal, domain B is forest green, the β-ribbon is purple, domain I is red, domain II is yellow, domain III is blue and the hydrophobic fusion loop (FL) is orange. Transmembrane regions are indicated with TM, signal peptide is indicated with SP and glycan positions are indicated with a Y. b The crystal structure of Gn from Rift Valley fever virus. Domains are coloured as in a and the position of a predicted glycan is indicated with a Y. c Structures of E2 and E3 from Chikungunya virus (CHIKV)¹⁷. d Structure of Gn from Puumala virus (PUUV)¹⁵. RVFV Gn adopts a novel fold but shares a similar domain organisation with CHIKV E2. Both proteins have a β-ribbon with two anti-parallel β-sheets and a domain B inserted into the β-ribbon. In CHIKV, E2 domain B is a β sandwich, while in RVFV Gn domain B is a small β sheet decorated with four short helices. Domain A of CHIKV E2 and PUUV Gn are both a seven stranded β sandwich with the same topology (Supplementary Figure 1)⁶¹