Analysis of the kinetoplast DNA of Leishmania panamensis

• Main Author: Brewster, S.
• Published: University of Cambridge 1999
• Subjects: 578.012
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596899

An in-depth study of the kinetoplast DNA of the human-infecting parasite <I>Leishmania panamensis</I> was conducted with the following objectives: • To find out how many minicircle sequence classes are present in the kinetoplast, and the relative abundance of each class; • To use this information to develop and test a kDNA-based diagnostic test specific for this species of parasite; • To investigate whether minicircle sequence data can be meaningfully used to infer phylogenetic relationships between <I>Leishmania</I> species; • To also investigate RNA editing in this parasite and compare it with previous results in a lizard-infecting <I>Leishmania</I>. Kinetoplast DNA from <I>L. panamensis</I> was cloned and investigated in detail by restriction enzyme typing and sequence analysis, and three other species of the <I>braziliensis</I> complex of New World <I>Leishmania</I> were analysed in a similar way. It was found that the minicircle component of the kinetoplast DNA is highly complex, and is comprised of at least 35 classes of minicircle per kinetoplast, with each class having a varying level of abundance. A kDNA probe and primers specific for <I>L. panamensis</I> were designed from an abundant minicircle class, and were subsequently field-tested in Medellin, Colombia. The sequence data generated during this study was used to infer phylogenetic relationships between the species of New World <I>Leishmania</I>. A variety of different approaches were used, and the suitability of this type of sequence data for phylogenetic analysis is discussed. The sequence data was also screened for potential guide RNA genes, and a total of 26 possible genes were identified. Comparison of the maxicircle gene sequence for the ATPase subunit 6 gene between <I>L. panamensis </I> and <I>L. tarentolae</I> (lizard-infecting) together with an analysis of previous work revealed that the RNA editing process is remarkably similar between <I>Leishmania</I> species. This study extends the little known about the organisation and function of minicircle DNA in pathogenic <I>Leishmania </I>species.