A new developmentally regulated gene family in Leishmania amastigotes encoding a homolog of amastin surface proteins

The ability of Leishmania to survive within the phagolysosomes of mammalian macrophages is heavily dependent on the developmental regulation of a numb er of genes. Characterization of genes preferentially expressed during the parasite's intracellular growth would help to elucidate the mechanisms cont rolling stage-specific gene regulation and the intracellular life of the pa rasite in general. Using a genomic approach based on the differential hybri dization screening of high-density filters, we have identified a new develo pmentally regulated gene in Leishmania, which is part of a multigene family and encodes a highly hydrophobic protein that shares homology with the Try panosoma cruzi amastin proteins. The fusion of the Leishmania amastin gene homolog with the green fluorescent protein and analysis by confocal microsc opy suggested a surface localization for this protein. The amastin gene hom olog is expressed predominantly in the amastigote form of several Leishmani a species and is strictly regulated by acidic pH at the post-transcriptiona l level. Its developmental expression involves sequences within the 3'-untr anslated region. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved .