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A Function for a Specific Zinc Metalloprotease of African Trypanosomes
Journal article   Open access   Peer reviewed

A Function for a Specific Zinc Metalloprotease of African Trypanosomes

Paul M Grandgenett, Keiko Otsu, Helen R Wilson, Mary E Wilson and John E Donelson
PLoS pathogens, Vol.3(10), pp.1432-1445
10/2007
DOI: 10.1371/journal.ppat.0030150
PMCID: PMC2034397
PMID: 17953481
url
https://doi.org/10.1371/journal.ppat.0030150View
Published (Version of record) Open Access

Abstract

The Trypanosoma brucei genome encodes three groups of zinc metalloproteases, each of which contains ∼30% amino acid identity with the major surface protease (MSP, also called GP63) of Leishmania . One of these proteases, TbMSP-B, is encoded by four nearly identical, tandem genes transcribed in both bloodstream and procyclic trypanosomes. Earlier work showed that RNA interference against TbMSP-B prevents release of a recombinant variant surface glycoprotein (VSG) from procyclic trypanosomes. Here, we used gene deletions to show that TbMSP-B and a phospholipase C (GPI-PLC) act in concert to remove native VSG during differentiation of bloodstream trypanosomes to procyclic form. When the four tandem TbMSP-B genes were deleted from both chromosomal alleles, bloodstream B −/− trypanosomes could still differentiate to procyclic form, but VSG was removed more slowly and in a non-truncated form compared to differentiation of wild-type organisms. Similarly, when both alleles of the single-copy GPI-PLC gene were deleted, bloodstream PLC −/− cells could still differentiate. However, when all the genes for both TbMSP-B and GPI-PLC were deleted from the diploid genome, the bloodstream B −/− PLC −/− trypanosomes did not proliferate in the differentiation medium, and 60% of the VSG remained on the cell surface. Inhibitors of cysteine proteases did not affect this result. These findings demonstrate that removal of 60% of the VSG during differentiation from bloodstream to procyclic form is due to the synergistic activities of GPI-PLC and TbMSP-B.
Infectious Diseases Eukaryotes Biochemistry Microbiology Molecular Biology

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