Crystal structure of the phosphate-binding protein (PBP-1) of an ABC-type phosphate transporter from Clostridium perfringens

Daniel Gonzalez (1) , Magali Richez (1) , Celine Bergonzi (1, 2) , Eric Chabriere (1) , Mikael Elias (2)

1 URMITE - Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes
2 Department of Biochemistry, Molecular Biology and Biophysics & Biotechnology Institute, St. Paul

Phosphate limitation is an important environmental stress that affects the metabolism of various organisms and, in particular, can trigger the virulence of numerous bacterial pathogens. Clostridium perfringens, a human pathogen, is one of the most common causes of enteritis necroticans, gas gangrene and food poisoning. Here, we focused on the high affinity phosphate-binding protein (PBP-1) of an ABC-type transporter, responsible for cellular phosphate uptake. We report the crystal structure (1.65 A ˚ resolution) of the protein in complex with phosphate. Interestingly, PBP-1 does not form the short, low-barrier hydrogen bond with phosphate that is typical of previously characterized phosphate-binding proteins, but rather a canonical hydrogen bond. In its unique binding configuration, PBP-1 forms an unusually high number of hydrogen bonds (14) with the phosphate anion. Discrimination experiments reveal that PBP-1 is the least selective PBP characterised so far and is able to discriminate phosphate from its close competing anion, arsenate, by ,150-fold. P hosphorus is essential for living organisms because it is involved in the composition of critical biomolecules (e.g., nucleic acids) and in key biological processes 1. Although phosphorus is relatively abundant on our planet, it is mostly trapped in rocks 2. Therefore, the bioavailability of phosphorus is limited, and living organisms have had to develop efficient mechanisms to extract phosphate from the environment 3. In prokaryotes, two main systems have been identified so far: (i) the Phosphate inorganic transport (Pit) and (ii) the Phosphate specific transport (Pst) systems. The Pit system is a single transmembrane component 4,5 , that is fueled by the proton-motive force and transports a divalent metal cation complexed with a phosphate anion 6. Pst, the predominant phosphate transporter 7 , is a classical ABC-transporter, composed of 5 proteins: 2 membrane permeases (PstA and PstC), 2 ATPases (PstB) and the high-affinity phosphate binding protein PstS (or phosphate-binding protein, PBP) 8. The Pst system is a high-affinity, high-specificity transporter that enables the extraction of phosphate from the environment 9,10

Keywords: ESCHERICHIA-COLI; PSEUDOMONAS-AERUGINOSA; MYCOBACTERIUM-TUBERCULOSIS; PATHOGENESIS; VIRULENCE; SYSTEM; VARIABILITY; SPECIFICITY; SEQUENCE; RECEPTOR

Domains: Life Sciences [q-bio]; Microbiology and Parasitology

Daniel Gonzalez, Magali Richez, Celine Bergonzi, Eric Chabriere, Mikael Elias. Crystal structure of the phosphate-binding protein (PBP-1) of an ABC-type phosphate transporter from Clostridium perfringens. Scientific Reports, 2014, 4 (6636 ), ⟨10.1038/srep06636⟩. ⟨hal-01244834⟩