title: Leishmania major: disruption of signal peptidase type I and its consequences on survival, growth and infectivity.
abstract: 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.
authors.affiliation: Molecular Immunology and Vaccine Research Lab, Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Tahereh
authors.initials: T
authors.lastname: Taheri
authors.forename: Ali-Hatef
authors.initials: AH
authors.lastname: Salmanian
authors.forename: Elham
authors.initials: E
authors.lastname: Gholami
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Doustdari
authors.forename: Farnaz
authors.initials: F
authors.lastname: Zahedifard
authors.forename: Sima
authors.initials: S
authors.lastname: Rafati
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D015971:Gene Expression Regulation, Enzymologic; D005822:Genetic Vectors; D005838:Genotype; D018320:Leishmania major / Q000187:drug effects / Q000201:enzymology* / Q000502:physiology / Q000648:ultrastructure; D016773:Leishmaniasis, Cutaneous / Q000469:parasitology*; D008264:Macrophages / Q000469:parasitology; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D010957:Plasmids / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012697:Serine Endopeptidases / Q000235:genetics / Q000502:physiology*; D014162:Transfection
chemical_list: D008565:Membrane Proteins; D012333:RNA, Messenger; D012697:Serine Endopeptidases; C026515:type I signal peptidase