4L7T

B. fragilis NanU

4L7T の概要

• エントリーDOI: 10.2210/pdb4l7t/pdb
• 分子名称: NanU sialic acid binding protein, ACETATE ION, 1,2-ETHANEDIOL, ... (5 entities in total)
• 機能のキーワード: susd-like, sialic acid binding, nano, outer membrane, sialic acid-binding protein
• 由来する生物種: Bacteroides fragilis
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 59951.08

構造登録者

Rafferty, J.B.,Phansopa, C.,Stafford, G.P. (登録日: 2013-06-14, 公開日: 2014-01-01, 最終更新日: 2024-02-28)

主引用文献

Phansopa, C.,Roy, S.,Rafferty, J.B.,Douglas, C.W.,Pandhal, J.,Wright, P.C.,Kelly, D.J.,Stafford, G.P.
Structural and functional characterization of NanU, a novel high-affinity sialic acid-inducible binding protein of oral and gut-dwelling Bacteroidetes species.
Biochem.J., 458:499-511, 2014

PubMed 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).

PubMed: 24351045
DOI: 10.1042/BJ20131415

実験手法

X-RAY DIFFRACTION (1.61 Å)