Phosphatase activity characterization on the surface of intact bloodstream forms of Trypanosoma brucei

• Published in: FEMS microbiology letters Vol. 220; no. 2; pp. 197 - 206
• Main Authors: Fernandes, Eloise Cedro, José Mauro Granjeiro, Eulázio Mikio Taga, Meyer-Fernandes, José Roberto, Aoyama, Hiroshi
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.03.2003
• Subjects: Acid phosphatase; Ascorbic acid; Calcium; Calcium ions; Carbon dioxide; Cell surface; Cobalt; Electrophoresis; Gel electrophoresis; Hydrogen peroxide; Iron; Kinases; Magnesium; Microbiology; Okadaic acid; p-Nitrophenylphosphate; Parasites; Phosphatase; Phosphoserine; Phosphotyrosine; Protozoa; Purification; Substrates; Trypanosoma brucei; Vanadate; Vanadates; Zinc
• DOI: 10.1016/S0378-10970300091-0
• ISSN: 0378-1097

Procyclic forms of Trypanosoma brucei possess a phosphatase activity on their external cell surface. This activity, while it dephosphorylates [32P]phosphocasein, is inhibited weakly by NaF and tartrate but strongly by vanadate. In this work, we describe the presence of an external phosphatase activity in intact bloodstream forms of T. brucei. With p-nitrophenyl phosphate (pNPP) as substrate, these intact cells produced 3–5 nmol pNP min−1 mg−1, linearly for up to at least 30 min. The activity was not significantly increased by Mg2+, Mn2+, Ca2+ and Co2+, but was inhibited by vanadate, NaF, p-chloromercuribenzoate and Zn2+ and was insensitive to okadaic acid. Membrane-enriched fractions of parasites contained an acid phosphatase activity, with a pH optimum in the range of 4.5–5.5. This activity hydrolyzed phosphotyrosine (40 nmol phosphate min−1 mg−1) better than phosphothreonine or phosphoserine. Partial purification of this phosphatase yielded a single activity band following gel electrophoresis, a Km value of 0.29 mM with pNPP and was insensitive to the Fe2+/H2O2/ascorbate system.