Journal of Biochemistry Advance Access originally published online on February 22, 2008
Journal of Biochemistry 2008 143(6):759-764; doi:10.1093/jb/mvn025
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© 2008 The Japanese Biochemical Society
Facilitation of Dissociation Reaction of Nucleotides Bound to Mycobacterium tuberculosis DnaA
1Graduate School of Bioresource and Bioenvironmental Science, Kyushu University, Fukuoka 812-8581, Japan; and 2Biomedical Research, The University of Texas Health Center at Tyler, Tyler, TX 75708-3154, USA
*To whom correspondence should be addressed. Tel: +81-92-621-4991, Fax: +81-92-624-1011, E-mail: yamamok{at}agr.kyushu-u.ac.jp
Received November 14, 2007; Accepted February 14, 2008
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Acidic phospholipids have been shown to promote dissociation of bound nucleotides from Mycobacterium tuberculosis DnaA (DnaATB) purified under denaturing conditions [Yamamoto et al., (2002) Modulation of Mycobacterium tuberculosis DnaA protein–adenine-nucleotide interactions by acidic phospholipids. Biochem. J., 363, 305–311]. In the present study, we show that a majority of DnaATB in non-overproducing cells of M. tuberculosis is membrane associated. Estimation of phospholipid phosphorus following chloroform: methanol extraction of soluble DnaATB purified under native conditions (nDnaATB) confirmed the association with phospholipids. nDnaATB exhibited weak ATPase activity, and rapidly exchanged ATP for bound ADP in the absence of any added phospholipids. We suggest that the outcome of intra-cellular DnaATB–nucleotide interactions, hence DnaATB activity, is influenced by phospholipids.
Key Words: ADP, ATP, ATPase, DNA replication, mycobacteria
Abbreviations: OriC, origin of replication; Trx, thioredoxin; PEI, polyethyleneimine