Abstract
Kinetoplast DNA (kDNA) is the mitochondrial genome of trypanosomatids. It consists of a few dozen maxicircles and several thousand minicircles, all catenated topologically to form a two-dimensional DNA network. Minicircles are heterogeneous in size and sequence among species. They present one or several conserved regions that contain three highly conserved sequence blocks. CSB-1 (10 bp sequence) and CSB-2 (8 bp sequence) present lower interspecies homology, while CSB-3 (12 bp sequence) or the Universal Minicircle Sequence is conserved within most trypanosomatids. The Universal Minicircle Sequence is located at the replication origin of the minicircles, and is the binding site for the UMS binding protein, a protein involved in trypanosomatid survival and virulence. Here, we describe the structure and organisation of the kDNA of Trypanosoma copemani, a parasite that has been shown to infect mammalian cells and has been associated with the drastic decline of the endangered Australian marsupial, the woylie (Bettongia penicillata). Deep genomic sequencing showed that T. copemani presents two classes of minicircles that share sequence identity and organisation in the conserved sequence blocks with those of Trypanosoma cruzi and Trypanosoma lewisi. A 19,257 bp partial region of the maxicircle of T. copemani that contained the entire coding region was obtained. Comparative analysis of the T. copemani entire maxicircle coding region with the coding regions of T. cruzi and T. lewisi showed they share 71.05% and 71.28% identity, respectively. The shared features in the maxicircle/minicircle organisation and sequence between T. copemani and T. cruzi/T. lewisi suggest similarities in their process of kDNA replication, and are of significance in understanding the evolution of Australian trypanosomes.
Highlights
IntroductionThe kinetoplast is a network of circular DNA (kDNA) inside a large mitochondrion
The kinetoplast is a network of circular DNA inside a large mitochondrion
Considering that the Universal Minicircle Sequence (UMS) element is present in C. fasciculata minicircles, and that it was found in T. copemani minicircles, we investigated the presence of a UMS binding protein (UMSBP) in T. copemani using antibodies raised against C. fasciculata UMSBP (Tzfati et al, 1995)
Summary
The kinetoplast is a network of circular DNA (kDNA) inside a large mitochondrion. It contains the mitochondrial genome, which consists of thousands of interlocked DNA circles of two types, maxicircles and minicircles that form a complex network (Lukeš et al, 2002; Jensen and Euglund, 2012). Their size ranges from approximately 20–40 Kb, depending upon the species, and they encode mitochondrial gene products (Shlomai, 2004).
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