A pentose bisphosphate pathway for nucleoside degradation in Archaea

Little is known about how Archaea break down the sugar parts of nucleosides. In most organisms, the pentose phosphate pathway handles this task. But in Archaea, this pathway is missing. This gap motivated researchers to explore alternative routes. Prior research has shown that Archaea use unique metabolic strategies. However, no prior work had resolved the specific mechanism for ribose degradation. This uncertainty drove the current investigation. The study aimed to uncover a possible metabolic network. The focus was on the archaeon Thermococcus kodakarensis.

The goal was to identify a metabolic route for ribose breakdown in Archaea. The researchers examined Thermococcus kodakarensis for such a pathway. They hypothesized that an alternative to the pentose phosphate pathway exists. The study aimed to map the enzymes involved in this process. The motivation was to understand how Archaea integrate nucleoside sugars into central metabolism. This would clarify a major gap in archaeal biochemistry. The researchers sought to determine the specific intermediates and enzymes. The study also aimed to name the newly identified pathway.

The team used biochemical assays to detect relevant enzymes. They analyzed the genome of Thermococcus kodakarensis for candidate genes. The researchers tested the activity of nucleoside phosphorylases. They also assessed the function of ribose-1-phosphate kinase. Two enzymes from a known NMP degradation pathway were included. The researchers examined ribose-1,5-bisphosphate isomerase. They studied the activity of type III ribulose-1,5-bisphosphate carboxylase/oxygenase. The team traced the flow of carbon through the proposed pathway.

The study identified a network of enzymes in Thermococcus kodakarensis. Three nucleoside phosphorylases were active in the pathway. An ADP-dependent ribose-1-phosphate kinase was also involved. The researchers confirmed the role of ribose-1,5-bisphosphate isomerase. Type III ribulose-1,5-bisphosphate carboxylase/oxygenase was active. Ribose 1,5-bisphosphate and ribulose 1,5-bisphosphate were detected as intermediates. These compounds linked nucleoside sugars to central carbon metabolism. The pathway was named the pentose bisphosphate pathway.

The study proposes a new pathway for ribose degradation in Archaea. The pentose bisphosphate pathway links nucleoside sugars to central metabolism. The pathway includes ribose-1,5-bisphosphate and ribulose-1,5-bisphosphate. The enzymes involved were confirmed through biochemical analysis. The findings suggest a unique metabolic strategy in Archaea. The pathway may differ from the pentose phosphate pathway in other organisms. The study supports the idea that Archaea use distinct biochemical routes. The results provide a framework for further research into archaeal metabolism.