Role of p38 in replication of Trypanosoma brucei kinetoplast DNA.
Trypanosomes have an unusual mitochondrial genome, called kinetoplast DNA, that is a giant network containing thousands of interlocked minicircles. During kinetoplast DNA synthesis, minicircles are released from the network for replication as theta-structures, and then the free minicircle progeny reattach to the network. We report that a mitochondrial protein, which we term p38, functions in kinetoplast DNA replication. RNA interference (RNAi) of p38 resulted in loss of kinetoplast DNA and accumulation of a novel free minicircle species named fraction S. Fraction S minicircles are so underwound that on isolation they become highly negatively supertwisted and develop a region of Z-DNA. p38 binds to minicircle sequences within the replication origin. We conclude that cells with RNAi-induced loss of p38 cannot initiate minicircle replication, although they can extensively unwind free minicircles.
Liu
Beiyu
B
Department of Biological Chemistry, Johns Hopkins Medical School, 725 N. Wolfe St., Baltimore, MD 21205, USA.
Molina
Henrik
H
Kalume
Dario
D
Pandey
Akhilesh
A
Griffith
Jack D
JD
Englund
Paul T
PT
D000818:Animals; D001483:Base Sequence; D004261:DNA Replication / Q000502:physiology*; D018105:DNA, Kinetoplast / Q000096:biosynthesis* / Q000235:genetics / Q000648:ultrastructure; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017125:Genes, Protozoan; D008854:Microscopy, Electron; D024101:Mitochondrial Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008954:Models, Biological; D040901:Proteomics; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D034622:RNA Interference; D014346:Trypanosoma brucei brucei / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure
D018105:DNA, Kinetoplast; D004268:DNA-Binding Proteins; D024101:Mitochondrial Proteins; D015800:Protozoan Proteins