Relationships between the major kinetoplastid paraflagellar rod proteins: a consolidating nomenclature.

Abstract

The Kinetoplastida comprise a family of flagellated microbes that are defined by the presence of a network of concatenated mitochondrial DNA called the kinetoplast and a range of other unique features. One such is the paraflagellar rod (PFR), which has an essential role in cell motility [1–3], an intricate sub-structural arrangement [4,5] and an interesting phylogenetic distribution [6,7]. Although the complete composition of the PFR is still unknown, the major structural components have been described in several species of Kinetoplastida. The first biochemical description in kinetoplastids identified the two major PFR proteins, PFR1 and PFR2, in Crithidia fasciculata [8]. In that paper, PFR1 was defined as the protein with the slower migration in SDS–PAGE gels while the faster migrating band was called PFR2. Since then, other descriptions of major PFR proteins in trypanosomatids have been made, including those of Herpetomonas megaseliae [9], Trypanosoma species [10,11] and Leishmania species [12,13]. At the time of many of these publications the correlation between major PFR proteins of different species was unclear and nomenclatures developed that were peculiar to each species and did not reflect the homologies amongst the proteins (see Table 1). However, with the increasing availability of DNA and protein sequences, we have now been able to define the levels of homology between PFR proteins (Fig. 1) and this reveals that the disconnected nomenclature