The O-antigen structure of bacterium Comamonas aquatica CJG

Area of Science:

• Microbiology
• Bacterial genetics
• Biochemistry

Background:

• Genus Comamonas bacteria are known for their environmental waste degradation capabilities.
• Comamonas aquatica CJG can absorb low-density lipoprotein but not high-density lipoprotein from human serum.

Purpose of the Study:

• To elucidate the O-polysaccharide (O-antigen) structure of Comamonas aquatica CJG.
• To analyze the O-antigen gene cluster for insights into its biosynthesis.

Main Methods:

• Proton (¹H) and Carbon-13 (¹³C) Nuclear Magnetic Resonance (NMR) spectroscopy were employed to determine the O-antigen structure.
• Analysis of the O-antigen gene cluster located between coaX and tnp4 genes.

Main Results:

• The O-polysaccharide of C. aquatica CJG consists of a disaccharide repeat unit composed of d-glucose and 2-O-acetyl-l-rhamnose.
• This O-antigen structure is identical to that found in Serratia marcescens O6.
• The O-antigen gene cluster contains genes for rhamnose synthesis, glycosyl and acetyl transferases, and ATP-binding cassette transporters.

Conclusions:

• The determined O-antigen structure of Comamonas aquatica CJG is confirmed by the genes present in its O-antigen gene cluster.
• The shared O-antigen structure suggests potential evolutionary or functional links between Comamonas aquatica CJG and Serratia marcescens O6.