Stage-specific expression of the Leishmania mexicana paraflagellar rod protein PFR-2.

A screen for Leishmania mexicana genes encoding promastigote-specific flagellar proteins resulted in isolation of genes encoding the major components of the paraflagellar rod. One of these, PFR-2, was characterized extensively. PFR-2 genes are present in the genome as a tandem array of three genes designated PFR-2A, PFR-2B, PFR-2C. PFR-2A and PFR-2B are encoded by a 3.1 transcript while PFR-2C is encoded by a 3.8-kb transcript that has a 3' UTR different from that of the 3.1-kb transcript. Both of these mRNAs were 15-fold more abundant in promastigotes than in amastigotes. Two transcripts immediately upstream of the locus were constitutively expressed while two downstream transcripts were fourfold more abundant in promastigotes than in amastigotes. The PFR genes will provide a good model system for analysis of stage-specific gene regulation in Leishmania as well as assist in the characterization of the function and organization of the paraflagellar rod.