Kinetoplast

A kinetoplast is a disk-shaped mass of circular DNA inside a large mitochondrion that contains many copies of the mitochondrial genome. Kinetoplasts are only found in protozoa of the class Kinetoplastida. Kinetoplasts are usually adjacent to the organisms' flagellar basal body leading to the thought that they are tightly bound to the cytoskeleton.

Trypanosoma

In Trypanosomes, a group of flagellated protozoans, the kinetoplast exists as a dense granule of DNA within the large mitochondrion. Trypanosoma brucei, the parasite which causes African trypanosomiasis (African sleeping sickness), is an example of a trypanosome with a kinetoplast. Its kinetoplast is easily visible in samples stained with DAPI, a fluorescent DNA stain.

The kinetoplast contains circular DNA in two forms - minicircles and maxicircles. Maxicircles are between 20 and 40kb in size and there are a few dozen per kinetoplast. There are several thousand minicricles per kinetoplast and these are between 0.5 and 1kb in size. The maxicircles encode the typical protein products needed for the mitochondria which is encrypted. Herein lies the only known function of the minicircles - producing guide RNA (gRNA) to decode this encrypted information. This unique mode of DNA replication may represent potential drug targets.