Biosynthesis of L-Erythrose by Assembly of Two Key Enzymes in Gluconobacter oxydans.

L-erythrose, a rare aldotetrose, possesses various pharmacological activities. However, efficient L-erythrose production is challenging. Currently, L-erythrose is produced by a two-step fermentation process from erythritol. Here, we describe a novel strategy for the production of L-erythrose in Gluconobacter oxydans (G. oxydans) by localizing the assembly of L-ribose isomerase (L-RI) to membrane-bound sorbitol dehydrogenase (SDH) via the protein-peptide interactions of the PDZ domain and PDZ ligand. To demonstrate this self-assembly, green fluorescent protein (GFP) replaced L-RI and its movement to membrane-bound SDH was observed by fluorescence microscopy. The final L-erythrose production was improved to 23.5 g/L with the stepwise metabolic engineering of G. oxydans, which was 1.4-fold higher than that obtained using coexpression of SDH and L-RI in G. oxydans. This self-assembly strategy shows remarkable potential for further improvement of L-erythrose production.