title: Plasmodium knowlesi: secondary processing of the malaria merozoite surface protein-1.
abstract: Secondary processing of the Plasmodium falciparum malaria merozoite surface protein-1 (MSP-1) is defined as a single proteolytic cleavage within the carboxy-terminal membrane-bound component of the MSP-1 protein complex on the free merozoite surface. The N-terminal cleavage product (MSP-1(33)) is shed from the parasite surface along with a number of other polypeptides, whereas the C-terminal processing product remains bound to the merozoite surface and is the only part of MSP-1 detectable in the newly invaded host cell. We report that secondary processing of MSP-1 takes place in a similar manner on invasive merozoites of the simian malaria parasite Plasmodium knowlesi. Processing can take place to a limited extent in pure isolated merozoites; however, within 10 min of the addition of purified invasive merozoites to rhesus erythrocytes, processing and shedding of MSP-1 has gone to completion only in those parasites which have undergone invasion; residual free merozoites remain uniformly reactive with antibodies against MSP-1(33). Successful invasion is therefore associated with complete shedding of MSP-1(33) from the merozoite surface. The nucleotide sequence of the 3' domain of the P. knowlesi MSP-1 gene is also presented.
authors.affiliation: Division of Parasitology, National Institute for Medical Research, London, United Kingdom. m-blackm@nimr.mrc.ac.uk
authors.forename: M J
authors.initials: MJ
authors.lastname: Blackman
authors.forename: E D
authors.initials: ED
authors.lastname: Dennis
authors.forename: E M
authors.initials: EM
authors.lastname: Hirst
authors.forename: C H
authors.initials: CH
authors.lastname: Kocken
authors.forename: T J
authors.initials: TJ
authors.lastname: Scott-Finnigan
authors.forename: A W
authors.initials: AW
authors.lastname: Thomas
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D017931:DNA Primers / Q000737:chemistry; D016054:DNA, Protozoan / Q000737:chemistry; D004912:Erythrocytes / Q000469:parasitology; D019085:Fluorescent Antibody Technique, Direct; D019084:Fluorescent Antibody Technique, Indirect; D008253:Macaca mulatta; D020066:Merozoite Surface Protein 1; D051379:Mice; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D016790:Plasmodium knowlesi / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011498:Protein Precursors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers; D016054:DNA, Protozoan; D020066:Merozoite Surface Protein 1; D011498:Protein Precursors; D015800:Protozoan Proteins