title: The leishmania ARL-1 and Golgi traffic.
abstract: We present here the characterisation of the Leishmania small G protein ADP-Ribosylation Factor-Like protein 1 (ARL-1). The ARL-1 gene is present in one copy per haploid genome and conserved among trypanosomatids. It encodes a protein of 20 kDa, which is equally expressed in the insect promastigote and mammalian amastigote forms of the parasite. ARL-1 localises to the Trans-Golgi Network (TGN); N-terminal myristoylation is essential for TGN localisation. In vivo expression of the LdARL-1/Q74L and LdARL-1/T51N mutants (GTP- and GDP-bound blocked forms respectively) shows that GDP/GTP cycling occurs entirely within the TGN. This is contrary to previous reports in yeast and mammals, where the mutant empty form devoid of nucleotide has been considered as the GDP-blocked form. The dominant-negative empty form mutant LdARL-1/T34N inhibits endocytosis and intracellular trafficking from the TGN to the Lysosome/Multivesicular Tubule and to the acidocalcisomes; these defects are probably related to a mislocalisation of the GRIP domain-containing vesicle tethering factors which cannot be recruited to the TGN by the cytoplasmic LdARL-1/T34N. Thus, besides the functional characterization of a new mutant and a better understanding of ARL-1 GDP/GTP cycling, this work shows that Leishmania ARL-1 is a key component of an essential pathway worth future study.
authors.affiliation: Laboratoire de Microbiologie Cellulaire et Moléculaire et Pathogénicité, UMR CNRS 5234, Université Bordeaux 2, Bordeaux, France.
authors.forename: Annelise
authors.initials: A
authors.lastname: Sahin
authors.forename: Benoît
authors.initials: B
authors.lastname: Espiau
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Tetaud
authors.forename: Armelle
authors.initials: A
authors.lastname: Cuvillier
authors.forename: Lydia
authors.initials: L
authors.lastname: Lartigue
authors.forename: Audrey
authors.initials: A
authors.lastname: Ambit
authors.forename: Derrick R
authors.initials: DR
authors.lastname: Robinson
authors.forename: Gilles
authors.initials: G
authors.lastname: Merlin
mesh_terms: D020727:ADP-Ribosylation Factors / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D006056:Golgi Apparatus / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D007891:Leishmania / Q000737:chemistry*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D021381:Protein Transport; D015800:Protozoan Proteins
chemical_list: D008565:Membrane Proteins; D015800:Protozoan Proteins; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; C097313:ADP-ribosylation factor related proteins; D020727:ADP-Ribosylation Factors