H. Daniell et al., ISOLATION AND CHARACTERIZATION OF AN IN-VITRO DNA-REPLICATION SYSTEM FROM MAIZE MITOCHONDRIA, Biochemical and biophysical research communications, 208(1), 1995, pp. 287-294
An in vitro DNA replication system from maize mitochondria has been is
olated and characterized. Maize mtDNA polymerase activity was purified
about 1100-fold through DEAE cellulose and Heparin-Sepharose columns.
In addition to the DNA polymerase activity, this in vitro replication
system also contained topoisomerase I, DNA primase and RNA polymerase
activities. Optimal conditions for enzyme activity, preferred templat
es and inhibitors were determined in order to further characterize thi
s in vitro replication system; this system was devoid of any detectabl
e extramitochondrial activity as determined by: a) the mt origin of th
e DNA polymerase activity as evidenced by studies using different temp
lates and inhibitors, b) absence of chloroplast or nuclear DNA, glucos
e -6-P-dehydrogenase (known to be present only in the cytosol and chlo
roplasts) and photosynthetic pigments in the mitochondrial fraction an
d c) the ability of maize mt topoisomerase I to relax positively super
coiled DNA. (C) 1995 Academic Press, Inc.