Leishmania donovani: Characterization and expression of ORFF, a gene amplified from the LDI locus

The LD1 locus is a 27.5-kb region of chromosome 35 that is conserved among all species of Leishmania and is amplified in several different isolates. H ere, we report the genomic distribution of ORFF, a gene from the LDI region , and its expression at the RNA and protein levels in two Indian isolates o f Leishmania donovani. In both of these isolates, ORFF was present as a sin gle copy on chromosome 35. Densitometric analysis of ORFF mRNA abundance re vealed relative abundance of 0.2 and 1.0 in AG83 and S-Lal, respectively. A ntiserum against recombinant ORFF protein detected a protein of the predict ed size (similar to 34 kDa) in both strains. The protein is most abundant i n mid-log-phase promastigotes and has a nuclear localization. The ORFF prot ein is preferentially expressed in L. donovani amastigotes but, in contrast , is expressed at higher levels in L. major promasti gores. (C) 1999 Academ ic Press.