Maxicircle (mitochondrial) genome sequence (partial) of Leishmania major: Gene content, arrangement and composition compared with Leishmania tarentolae

Abstract

We report 8420 bp of DNA sequence data from the maxicircle (mitochondrial) genome of Leishmania major (MHOM/SU/73/5ASKH), a much larger portion of this genome than has been reported previously from any Leishmania species infecting humans. This region contains 10 partial and complete genes: 5 protein-encoding genes ( COII, COIII, ND1, ND7 and Cyt b); two ribosomal RNA subunits ( 12S and 9S) and three unidentified open reading frames ( MURF1, MURF4 ( ATPase6) and MURF5), as in the lizard-infecting species L. tarentolae. The genes from L. major exhibit 85–87% identity with those of L. tarentolae at the nucleotide level and 71–94% identity at the amino acid level. Most differences between sequences from the two species are transversions. The gene order and arrangement within the maxicircle of L. major are similar to those in L. tarentolae, but base composition and codon usage differ between the species. Codons assigned for initiation for protein-coding genes available for comparison are similar in five genes in the two species. Pre-editing was identified in some of the protein-coding genes. Short intergenic non-coding regions are also present in L. major as they are in L. tarentolae. Intergenic regions between 9S rRNA and MURF5, MURF1 and ND1 genes are G+C rich and considered to be extensive RNA editing regions. The RNA editing process is likely to be conserved in similar pattern in L. major as in L. tarentolae.