The first structure of a bacterial class B Acid phosphatase reveals further structural heterogeneity among phosphatases of the haloacid dehalogenase fold.
AphA is a periplasmic acid phosphatase of Escherichia coli belonging to class B bacterial phosphatases, which is part of the DDDD superfamily of phosphohydrolases. The crystal structure of AphA has been determined at 2.2A and its resolution extended to 1.7A on an AuCl(3) derivative. This represents the first crystal structure of a class B bacterial phosphatase. Despite the lack of sequence homology, the AphA structure reveals a haloacid dehalogenase-like fold. This finding suggests that this fold could be conserved among members of the DDDD superfamily of phosphohydrolases. The active enzyme is a homotetramer built by using an extended N-terminal arm intertwining the four monomers. The active site of the native enzyme, as prepared, hosts a magnesium ion, which can be replaced by other metal ions. The structure explains the non-specific behaviour of AphA towards substrates, while a structure-based alignment with other phosphatases provides clues about the catalytic mechanism.
Calderone
Vito
V
Dipartimento di Chimica, Università di Siena, Via Aldo Moro, I-53100 Siena, Italy.
Forleo
Costantino
C
Benvenuti
Manuela
M
Cristina Thaller
Maria
M
Rossolini
Gian Maria
GM
Mangani
Stefano
S
D000135:Acid Phosphatase / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D018360:Crystallography, X-Ray; D006867:Hydrolases / Q000737:chemistry*; D008274:Magnesium; D008958:Models, Molecular; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry*; D011487:Protein Conformation; D020836:Protein Structure, Quaternary; D016415:Sequence Alignment; D040681:Structural Homology, Protein; D013379:Substrate Specificity
D001426:Bacterial Proteins; D006867:Hydrolases; C070989:phosphoenolpyruvate phosphatase; D000135:Acid Phosphatase; D010744:Phosphoric Monoester Hydrolases; C034507:2-haloacid dehalogenase; D008274:Magnesium