Fig. 1

Metabolic scheme for engineering Synechocystis strains. L-arabinose may enter the transformant strains by means of native transporter/s such as GlcP and heterologous transporters such as AraE, AraFGH and AraJ. Direction of entry and exit of sugars (established, indicated in this study and putative) is shown using dotted arrows. L-arabinose is converted to L-ribulose by L-arabinose isomerase (AraA) in the presence of manganese ions (Mn⁺²). L-ribulose is phosphorylated to L-ribulose 5-phosphate (L-Ru5P) by the action of L-ribulokinase (AraB). L-Ru5P is converted by L-ribulose 5-phosphate 4-epimerase (AraD) in the presence of zinc ions (Zn⁺²) to D-xylulose 5-phosphate (D-Xu5P), which enters the pentose phosphate pathway (PPP). Bidirectional arrows indicate a reversible reaction or connections between metabolic pathways through intermediates. Unidirectional arrows indicate a non-reversible reaction or the ability of a sugar or an intermediate to either enter or exit a pathway. Dashed arrows indicate the involvement of one or more intermediates. Question marks (?) indicate putative transport of L-arabinose. Other abbreviations: ADP, adenosine diphosphate; ATP, adenosine triphosphate