Trypanosomes Have Six Mitochondrial DNA Helicases with One Controlling Kinetoplast Maxicircle Replication

Stem-loop silencing reveals that a third mitochondrial DNA polymerase, POLID, is required for kinetoplast DNA replication in trypanosomes.

Kinetoplast DNA (kDNA), the mitochondrial genome of trypanosomes, is a catenated network containing thousands of minicircles and tens of maxicircles. The topological complexity dictates some unusual features including a topoisomerase-mediated release-and-reattachment mechanism for minicircle replication and at least six mitochondrial DNA polymerases (Pols) for kDNA transactions. Previously, we ...

Isolation of maxicircle component of kinetoplast DNA from hemoflagellate protozoa.

Maxicircle DNA has been isolated from the kinetoplast DNA of Leishmania tarentolae culture forms by bouyant separation in CsCl in the presence of the A + T-binding dye Hoechst 33258, after liberation from the kinetoplast DNA network by cleavage with the single-hit restriction endonuclease EcoRI. The purified linearized maxicircle DNA has a density in CsCl of 1.681 g/cm3 (79% A + T) and a molecu...

Kinetoplast DNA Replication

The order Kinetoplastida is composed of several families of flagellated protozoa which are among the most ancient of the eukaryotes. The most prominent members of this order are parasites that are responsible for major tropical diseases. These parasites include Trypanosoma brucei, the African trypanosome; Trypanosoma cruzi, the South American trypanosome; and several species of Leishmania. Othe...

Effects of Trypanocidal Drugs on the Replication and Function of Kinetoplast (mitochondria!.) Dna in Trypanosomes

TbPIF1, a Trypanosoma brucei mitochondrial DNA helicase, is essential for kinetoplast minicircle replication.

Kinetoplast DNA, the trypanosome mitochondrial genome, is a network of interlocked DNA rings including several thousand minicircles and a few dozen maxicircles. Minicircles replicate after release from the network, and their progeny reattach. Remarkably, trypanosomes have six mitochondrial DNA helicases related to yeast PIF1 helicase. Here we report that one of the six, TbPIF1, functions in min...