Release of ecto-protein kinases by the protozoan parasite Leishmania major

N. Sacerdoti-Sierra, C. L. Jaffe*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

45 Scopus citations

Abstract

Leishmania major promastigotes have externally oriented ecto-protein kinases (PK) that are capable of phosphorylating both endogenous membrane substrates and foreign proteins. Live parasites phosphorylate protamine sulfate, casein, and phosvitin but not bovine serum albumin. Addition of exogenous PK substrates, such as phosvitin or casein, induced the shedding of ecto-PK that are capable of phosphorylating protamine sulfate. No phosphorylation of protamine sulfate was seen when cell-free supernatants from promastigotes incubated with either buffer alone or bovine serum albumin were used. A second enzyme, a constitutively released PK that phosphorylates casein or phosvitin and not protamine sulfate or mixed histones, was identified and characterized. This PK is inhibited by 5 μM staurosporine, 50 μg/ml heparin, and 75 μM CKI-7, concentrations typical of the ICA50 found for other eukaryotic casein kinases (CK). The constitutively shed ecto-PK specifically phosphorylated a peptide substrate for CK1 but not for CK2, suggesting that this shed PK is similar to CK1.

Original languageAmerican English
Pages (from-to)30760-30765
Number of pages6
JournalJournal of Biological Chemistry
Volume272
Issue number49
DOIs
StatePublished - 1997

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