Premium
A mitochondrial topoisomerase IA essential for late theta structure resolution in African trypanosomes
Author(s) -
Scocca Jane R.,
Shapiro Theresa A.
Publication year - 2008
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2007.06087.x
Subject(s) - biology , kinetoplast , topoisomerase , trypanosoma brucei , mitochondrial dna , mitochondrion , kinetoplastida , dna , trypanosoma , dna replication , microbiology and biotechnology , genetics , gene , protozoal disease , malaria , immunology
Summary Trypanosomes and Leishmania , protozoans that cause major human diseases, have a topologically intricate mitochondrial DNA (kinetoplast or kDNA) in the form of a network of thousands of interlocked circles. This unusual system provides a useful reporter for studying topoisomerase functions in vivo . We now find that these organisms have three type IA topoisomerases, one of which is phylogenetically distinctive and which we designate topoisomerase IA mt . In Trypanosoma brucei topoisomerase IA mt immunolocalizes within the mitochondrion close to the kDNA disk in patterns that vary with the cell cycle. When expression of TOPIA mt is silenced by RNAi there is a striking accumulation of kDNA late theta structure replication intermediates, with subsequent loss of kDNA networks and halt in cell growth. This essential enzyme provides clear molecular evidence for the obligatory role of a type IA enzyme in the resolution of late theta structures in vivo . With no close orthologue in humans it also offers a target for the rational development of selectively toxic new antiprotozoal therapies.