(A). A schematic of the N-terminal Ferredoxin-HydA1 fusion protein showing the relative positions of Ferredoxin, (Fd) peptide linker with TEV protease site (TEV protease), HydA1 and the Factor XA Protease and StrepII-tag (Strep II). HydA1 (C. reinhardtii HYDA1) is the mature protein sequence (without the chloroplast transit peptide). (B). The pHydEFd-HydA1 plasmid is a derivative of pETDuet (Invitrogen, USA) that allows for IPTG-inducible co-expression of the HydE and Fd-HydA1 proteins [11]. The relative locations of HydE, Fd, TEV protease site, HydA1, Factor Xa protease site and the StrepII tag are shown. T7P1, T7 polymerase promoter 1; T7P2, T7 polymerase promoter 2; T7ter, T7 transcriptional terminator; AmpR, ampicillin resistance marker; pBR322 ori, origin of replication; and LacI, lactose repressor gene.