Abstract:
BACKGROUND : Protein glycosylation involves the post-translational attachment of sugar chains to target proteins and
has been observed in all three domains of life. Post-translational glycosylation of flagellin, the main structural
protein of the flagellum, is a common characteristic among many Gram-negative bacteria and Archaea. Several distinct
functions have been ascribed to flagellin glycosylation, including stabilisation and maintenance of the flagellar filament,
motility, surface recognition, adhesion, and virulence. However, little is known about this trait among Gram-positive
bacteria.
RESULTS : Using comparative genomic approaches the flagellin glycosylation loci of multiple strains of the Gram-positive
thermophilic genus Geobacillus were identified and characterized. Eighteen of thirty-six compared strains of the genus
carry these loci, which show evidence of horizontal acquisition. The Geobacillus flagellin glycosylation islands (FGIs) can
be clustered into five distinct types, which are predicted to encode highly variable glycans decorated with distinct and
heavily modified sugars.
CONLUSIONS : Our comparative genomic analyses showed that, while not universal, flagellin glycosylation islands are
relatively common among members of the genus Geobacillus and that the encoded flagellin glycans are highly
variable. This suggests that flagellin glycosylation plays an important role in the lifestyles of members of this
thermophilic genus.
