PUL ID

PUL0244

PubMed

24351045, Biochem J. 2014 Mar 15;458(3):499-511. doi: 10.1042/BJ20131415.

Characterization method

gene deletion mutant and growth assay, complementation study, carbohydrate binding assay

Genomic accession number

JUET01000139.1

Nucelotide position range

87387-102782

Substrate

sialic acid

Loci

TAnf_13685-Tanf_13725

Species

Tannerella forsythia/28112

Degradation or Biosynthesis

degradation

Cluster number

1

Gene name

Gene position

Gene type

Found by CGCFinder?

- 1 - 1215 (-) CDS No
- 1223 - 3301 (-) CDS No
- 3319 - 5316 (-) CAZyme: GH20 Yes
- 5313 - 6932 (-) CAZyme: GH33 Yes
- 7013 - 8581 (-) TC: gnl|TC-DB|Q5LEN2|8.A.46.1.4 Yes
- 8612 - 11908 (-) TC: gnl|TC-DB|Q93TH9|1.B.14.6.2 Yes
- 12028 - 13272 (-) TC: gnl|TC-DB|Q07YH1|2.A.1.14.25 Yes
- 13297 - 14475 (-) CDS No
- 14482 - 15396 (-) CDS No

PUL ID

PUL0244

PubMed

24351045, Biochem J. 2014 Mar 15;458(3):499-511. doi: 10.1042/BJ20131415.

Title

Structural and functional characterization of NanU, a novel high-affinity sialic acid-inducible binding protein of oral and gut-dwelling Bacteroidetes species.

Author

Phansopa C, Roy S, Rafferty JB, Douglas CW, Pandhal J, Wright PC, Kelly DJ, Stafford GP

Abstract

Many human-dwelling bacteria acquire sialic acid for growth or surface display. We identified previously a sialic acid utilization operon in Tannerella forsythia that includes a novel outer membrane sialic acid-transport system (NanOU), where NanO (neuraminate outer membrane permease) is a putative TonB-dependent receptor and NanU (extracellular neuraminate uptake protein) is a predicted SusD family protein. Using heterologous complementation of nanOU genes into an Escherichia coli strain devoid of outer membrane sialic acid permeases, we show that the nanOU system from the gut bacterium Bacteroides fragilis is functional and demonstrate its dependence on TonB for function. We also show that nanU is required for maximal function of the transport system and that it is expressed in a sialic acid-responsive manner. We also show its cellular localization to the outer membrane using fractionation and immunofluorescence experiments. Ligand-binding studies revealed high-affinity binding of sialic acid to NanU (Kd ~400 nM) from two Bacteroidetes species as well as binding of a range of sialic acid analogues. Determination of the crystal structure of NanU revealed a monomeric SusD-like structure containing a novel motif characterized by an extended kinked helix that might determine sugar-binding specificity. The results of the present study characterize the first bacterial extracellular sialic acid-binding protein and define a sialic acid-specific PUL (polysaccharide utilization locus).