Site 2 of the Yersinia pestis substrate-binding protein YfeA is a dynamic surface metal-binding site.
Radka, C.D., Aller, S.G.(2021) Acta Crystallogr F Struct Biol Commun 77: 286-293
- PubMed: 34473105 
- DOI: https://doi.org/10.1107/S2053230X21008086
- Primary Citation of Related Structures:  
7ME1 - PubMed Abstract: 
The substrate-binding protein YfeA (also known as YPO2439 or y1897) is a polyspecific metal-binding protein that is crucial for nutrient acquisition and virulence in Yersinia pestis, the causative microbe of plague. YfeA folds into a monomeric c-clamp like other substrate-binding proteins and has two metal-binding sites (sites 1 and 2). Site 2 is a bidentate surface site capable of binding Zn and Mn atoms and is a unique feature of YfeA. Occasionally, the site 2 residues of two YfeA molecules will cooperate with the histidine tag of a third YfeA molecule in coordinating the same metal and lead to metal-dependent crystallographic packing. Here, three crystal structures of YfeA are presented at 1.85, 2.05 and 2.25 Å resolution. A comparison of the structures reveals that the metal can be displaced at five different locations ranging from ∼4 to ∼16 Å away from the canonical site 2. These observations reveal different configurations of site 2 that enable cooperative metal binding and demonstrate how site 2 is dynamic and freely available for inter-protein metal coordination.
Organizational Affiliation: 
Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, TN 38105, USA.