Synthase-dependent exopolysaccharide secretion in Gram-negative bacteria

Trends Microbiol. 2013 Feb;21(2):63-72. doi: 10.1016/j.tim.2012.10.001. Epub 2012 Oct 29.


The biosynthesis and export of bacterial cell-surface polysaccharides is known to occur through several distinct mechanisms. Recent advances in the biochemistry and structural biology of several proteins in synthase-dependent polysaccharide secretion systems have identified key conserved components of this pathway in Gram-negative bacteria. These components include an inner-membrane-embedded polysaccharide synthase, a periplasmic tetratricopeptide repeat (TPR)-containing scaffold protein, and an outer-membrane β-barrel porin. There is also increasing evidence that many synthase-dependent systems are post-translationally regulated by the bacterial second messenger bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP). Here, we compare these core proteins in the context of the alginate, cellulose, and poly-β-D-N-acetylglucosamine (PNAG) secretion systems.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Alginates
  • Bacterial Proteins / metabolism*
  • Bacterial Secretion Systems / physiology
  • Cellulose / biosynthesis
  • Glucuronic Acid / biosynthesis
  • Gram-Negative Bacteria / metabolism*
  • Hexuronic Acids
  • Polysaccharides, Bacterial / biosynthesis
  • Polysaccharides, Bacterial / metabolism*
  • beta-Glucans / metabolism


  • Alginates
  • Bacterial Proteins
  • Bacterial Secretion Systems
  • Hexuronic Acids
  • Polysaccharides, Bacterial
  • beta-Glucans
  • poly-N-acetyl-1-6-glucosamine
  • Glucuronic Acid
  • Cellulose