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

TitleStem-loop silencing reveals that a third mitochondrial DNA polymerase, POLID, is required for kinetoplast DNA replication in trypanosomes.
Publication TypeJournal Article
Year of Publication2008
AuthorsChandler J, Vandoros AV, Mozeleski B, Klingbeil MM
JournalEukaryot Cell
Volume7
Issue12
Pagination2141-6
Date Published2008 Dec
ISSN1535-9786
KeywordsAnimals, DNA Replication, DNA, Kinetoplast, DNA-Directed DNA Polymerase, Mitochondria, Mitochondrial Proteins, Protozoan Proteins, RNA Interference, RNA, Double-Stranded, Trypanosoma brucei brucei
Abstract

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 identified four family A DNA Pols from Trypanosoma brucei with similarity to bacterial DNA Pol I and demonstrated that two (POLIB and POLIC) were essential for maintaining the kDNA network, while POLIA was not. Here, we used RNA interference to investigate the function of POLID in procyclic T. brucei. Stem-loop silencing of POLID resulted in growth arrest and the progressive loss of the kDNA network. Additional defects in kDNA replication included a rapid decline in minicircle and maxicircle abundance and a transient accumulation of minicircle replication intermediates before loss of the kDNA network. These results demonstrate that POLID is a third essential DNA Pol required for kDNA replication. While other eukaryotes utilize a single DNA Pol (Pol gamma) for replication of mitochondrial DNA, T. brucei requires at least three to maintain the complex kDNA network.

DOI10.1128/EC.00199-08
Alternate JournalEukaryotic Cell
PubMed ID18849470