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Exp Parasitol. 2010 Oct;126(2):135-45. doi: 10.1016/j.exppara.2010.04.009. Epub 2010 Apr 22.

Leishmania major: disruption of signal peptidase type I and its consequences on survival, growth and infectivity.

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  • 1Molecular Immunology and Vaccine Research Lab, Pasteur Institute of Iran, Tehran, Iran.


Leishmania major (L. major) signal peptidase type I (SPase I) is an endopeptidase encoded by a single-copy gene. In all organisms, SPase I is responsible for removing the signal peptide from secretory pre-proteins and releasing mature proteins to cellular or extra-cellular space. In this study, the role of SPase I in L. major is investigated by gene deletion using homologous recombination (HR). The null mutant of SPase I was not possible to create, suggesting that SPase I is an essential gene for parasite survival. The obtained heterozygote mutant by disrupting one allele of SPase I in L. major showed significantly reduced level of infectivity in bone marrow-derived macrophages. In addition, the heterozygote mutants are unable to cause cutaneous lesion in susceptible BALB/c mice. This is the first report showing that SPase I may have an important role in Leishmania infectivity, e.g. in differentiation and survival of amastigotes. Apparently, the SPase I expression is not essential for in vitro growth of the parasite.

Copyright 2010 Elsevier Inc. All rights reserved.

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