Biosynthesis of Polysaccharides

Polysaccharides like glycogen and starch are synthesized from nucleoside diphosphate sugars such as uridine diphosphate glucose— UDPG or adenosine diphosphate glucose— ADPG.

It occurs on a preexisting polymer fragment, serving as a chain elongation primer.

Glycogen or starch synthases extend these chains by adding glucose units to their non-reducing ends.

UDPG forms when glucose-1-phosphate reacts with uridine triphosphate, catalyzed by UDP-glucose pyrophosphorylase.

UDP sugars play a crucial role in bacterial cell wall biosynthesis.

Similarly, ADPG, synthesized from glucose-1-phosphate and adenosine triphosphate via ADP-glucose pyrophosphorylase, plays a key role in glycogen and starch synthesis.

Beyond direct synthesis, cells can generate glucose through gluconeogenesis, utilizing non-carbohydrate sources such as lactate, amino acids, and glycerol.

This glucose can be converted into UDPG or ADPG for polysaccharide biosynthesis.

These polysaccharides support microbial survival by contributing to cell wall biosynthesis, carbon storage, and energy conservation.