title: Identification of a class B acid phosphatase in Haemophilus parasuis.
abstract: An acid phosphatase activity was detected in the supernatant of Haemophilus parasuis, a Gram-negative pleomorphic bacillus and the causative agent of Glässer's disease in pigs. To identify the gene responsible for the secreted activity, a genomic library of H. parasuis strain ER-6P was produced in Escherichia coli. Screening of the library allowed identification of two homologs to known phosphatases: PgpB and AphA. PgpB was predicted to be located in the bacterial membrane through six transmembrane domains while AphA was predicted to have a signal peptide. The aphA gene was cloned and expressed in E. coli. Characterization of H. parasuis AphA indicated that this protein belongs to the class B nonspecific acid phosphatases. AphA contained sequence signatures characteristic of this family of phosphatases and its activity was inhibited by EDTA. The optimal pH of recombinant AphA differed from that of the phosphatase activity found in H. parasuis supernatants. In addition, the phosphatase activity from H. parasuis supernatants was not inhibited by EDTA, indicating that H. parasuis AphA does not account for the phosphatase activity observed in the supernatants. Our results demonstrate the presence of a class B acid phosphatase (AphA) in H. parasuis and suggest that the bacterium would also secrete another, as yet unidentified phosphatase.
authors.affiliation: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autonoma de Barcelona, Bellaterra, Barcelona, Spain.
authors.forename: Paula
authors.initials: P
authors.lastname: Manrique-Ramírez
authors.affiliation: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autonoma de Barcelona, Bellaterra, Barcelona, Spain.
authors.forename: Núria
authors.initials: N
authors.lastname: Galofré-Milà
authors.affiliation: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autonoma de Barcelona, Bellaterra, Barcelona, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Serrano
authors.affiliation: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autonoma de Barcelona, Bellaterra, Barcelona, Spain.|Institut de Recerca i Tecnologia Agroalimentàries (IRTA), Barcelona, Spain.
authors.forename: Virginia
authors.initials: V
authors.lastname: Aragón
mesh_terms: D000135:Acid Phosphatase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D004795:Enzyme Stability; D044137:Haemophilus parasuis / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D016415:Sequence Alignment
chemical_list: D001426:Bacterial Proteins; D000135:Acid Phosphatase
keywords: Glässer’s disease; Haemophilus parasuis; non-specifi c acid phosphatases; phosphatase activity; xylem-limited bacteria