[Whole-cell catalytic production of pseudouridine by recombinant Escherichia coli]

Pseudouridine is the most abundant modified nucleoside found in non-coding RNA and is widely used in biological and pharmaceutical fields. However, current methods for pseudouridine production suffer from drawbacks such as complex procedures, low efficiency and high costs. This study presents a novel enzymatic cascade reaction route in Escherichia coli, enabling the whole-cell catalytic synthesis of pseudouridine from uridine. Initially, a metabolic pathway was established through plasmid-mediated overexpression of endogenous pseudouridine-5-phosphase glycosidase, ribokinase, and ribonucleoside hydrolase, resulting in the accumulation of pseudouridine. Subsequently, highly active endogenous ribonucleoside hydrolase was screened to enhance uridine hydrolysis and provide more precursors for pseudouridine synthesis. Furthermore, modifications were made to the substrates and products transport pathways to increase the pseudouridine yield while avoiding the accumulation of by-product uridine. The resulting recombinant strain Ψ-7 catalyzed the conversion of 30 g/L uridine into 27.24 g/L pseudouridine in 24 h, achieving a conversion rate of 90.8% and a production efficiency of 1.135 g/(L·h). These values represent the highest reported yield and production efficiency achieved by enzymatic catalysis methods to date.