TY - JOUR
T1 - Membrane-catalyzed nucleotide exchange on DnaA
T2 - Effect of surface molecular crowding
AU - Aranovich, Alexander
AU - Gdalevsky, Garik Y.
AU - Cohen-Luria, Rivka
AU - Fishov, Itzhak
AU - Parola, Abraham H.
PY - 2006/5/5
Y1 - 2006/5/5
N2 - DnaA is the initiator protein for chromosomal replication in bacteria; its activity plays a central role in the timing of the primary initiations within the Escherichia coli cell cycle. A controlled, reversible conversion between the active ATP-DnaA and the inactive ADP forms modulates this activity. In a DNA-dependent manner, bound ATP is hydrolyzed to ADP. Acidic phospholipids with unsaturated fatty acids are capable of reactivating ADP-DnaA by promoting the release of the tightly bound ADP. The nucleotide dissociation kinetics, measured in the present study with the fluorescent derivative 3′-O-(N- methylantraniloyl)-5′-adenosine triphosphate, was dependent on the density of DnaA on the membrane in a cooperative manner: it increased 5-fold with decreased protein density. At all surface densities the nucleotide was completely released, presumably due to protein exchange on the membrane. Distinct temperature dependences and the effect of the crowding agent Ficoll suggest that two functional states of DnaA exist at high and low membrane occupancy, ascribed to local macromolecular crowding on the membrane surface. These novel phenomena are thought to play a major role in the mechanism regulating the initiation of chromosomal replication in bacteria.
AB - DnaA is the initiator protein for chromosomal replication in bacteria; its activity plays a central role in the timing of the primary initiations within the Escherichia coli cell cycle. A controlled, reversible conversion between the active ATP-DnaA and the inactive ADP forms modulates this activity. In a DNA-dependent manner, bound ATP is hydrolyzed to ADP. Acidic phospholipids with unsaturated fatty acids are capable of reactivating ADP-DnaA by promoting the release of the tightly bound ADP. The nucleotide dissociation kinetics, measured in the present study with the fluorescent derivative 3′-O-(N- methylantraniloyl)-5′-adenosine triphosphate, was dependent on the density of DnaA on the membrane in a cooperative manner: it increased 5-fold with decreased protein density. At all surface densities the nucleotide was completely released, presumably due to protein exchange on the membrane. Distinct temperature dependences and the effect of the crowding agent Ficoll suggest that two functional states of DnaA exist at high and low membrane occupancy, ascribed to local macromolecular crowding on the membrane surface. These novel phenomena are thought to play a major role in the mechanism regulating the initiation of chromosomal replication in bacteria.
UR - http://www.scopus.com/inward/record.url?scp=33744958175&partnerID=8YFLogxK
U2 - 10.1074/jbc.M510266200
DO - 10.1074/jbc.M510266200
M3 - Article
AN - SCOPUS:33744958175
SN - 0021-9258
VL - 281
SP - 12526
EP - 12534
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 18
ER -