Structures of Streptococcus pneumoniae PiaA and its complex with ferrichrome reveal insights into the substrate binding and release of high affinity iron transporters.

ABSTRACT: Iron scarcity is one of the nutrition limitations that the Gram-positive infectious pathogens Streptococcus pneumoniae encounter in the human host. To guarantee sufficient iron supply, the ATP binding cassette (ABC) transporter Pia is employed to uptake iron chelated by hydroxamate siderophore, via the membrane-anchored substrate-binding protein PiaA. The high affinity towards ferrichrome enables PiaA to capture iron at a very low concentration in the host. We presented here the crystal structures of PiaA in both apo and ferrichrome-complexed forms at 2.7 and 2.1 Å resolution, respectively. Similar to other class III substrate binding proteins, PiaA is composed of an N-terminal and a C-terminal domain bridged by an α-helix. At the inter-domain cleft, a molecule of ferrichrome is stabilized

SUBMITTER: Cheng W 

PROVIDER: S-EPMC3741162 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature