FIGURE 5.

Proposed modes of replication that might co-exist in C. parapsilosis mitochondria. The filled black circle indicates the switching point of the two major transcriptional units. In mode 1, unidirectional replication initiates from the left TR exposing ssDNA of the upper strand. Proceeding through the molecule, lagging-strand synthesis initiates at different locations thus explaining the occurrence of ssDNA of different lengths along the mtDNA of C. parapsilosis. Mode 2 accounts for the possibility of RDR facilitated by transcription (RNA is depicted as broken line). Transcription can support strand invasions to initiate strand-coupled and/or bidirectional replication. Mode 3 is proposed based on observations as presented in Figs. 1 and 3; strand invasions (due to homologous recombination by t-circles or self-invasion of main-molecules) may provide primers for replication initiation at random locations across the C. parapsilosis mtDNA or from the TR toward the respective opposite ends. As soon as the replisome reaches the coding regions, replication proceeds in a strand-coupled mode (Fig. 1 formation of Y-arcs).