Sialic Acid Transporter NanT Participates in Tannerella forsythia Biofilm Formation and Survival on Epithelial Cells
Article, Other literature type
Frey, Andrew. M.
Stafford, Graham P.
- Publisher: Elsevier
mesheuropmc: stomatognathic diseases
Tannerella forsythia is a periodontal pathogen
implicated in periodontitis. This gram-negative pathogen depends on exogenous
peptidoglycan amino sugar N-acetylmuramic acid (NAM) for growth. In the biofilm
state the bacterium can utilize sialic acid (Neu5Ac) instead of NAM to sustain
its growth. Thus, the sialic acid utilization system of the bacterium plays a
critical role in the growth and survival of the organism in the absence of NAM.
We sought the function of a T. forsythia gene annotated as
nanT coding for an inner-membrane sugar transporter located
on a sialic acid utilization genetic cluster. To determine the function of this
putative sialic acid transporter, an isogenic nanT-deletion
mutant generated by allelic replacement strategy was evaluated for biofilm
formation on NAM or Neu5Ac, and survival on KB epithelial cells. Moreover, since
T. forsythia forms synergistic biofilms with
Fusobacterium nucleatum, co-biofilm formation activity in
mixed culture and sialic acid uptake in culture were also assessed. The data
showed that the nanT-inactivated mutant of T.
forsythia was attenuated in its ability to uptake sialic acid. The
mutant formed weaker biofilms compared to the wild-type strain in the presence
of sialic acid and as co-biofilms with F. nucleatum. Moreover,
compared to the wild-type T. forsythia nanT -inactivated mutant
showed reduced survival when incubated on KB epithelial cells. Taken together,
the data presented here demonstrate that NanT-mediated sialic transportation is
essential for sialic acid utilization during biofilm growth and survival of the
organism on epithelial cells and implies sialic acid might be key for its
survival both in subgingival biofilms and during infection of human epithelial
cells in vivo.