TY - JOUR
T1 - On the localization of the origin of DNA replication in E. coli
AU - Litwin, Samuel
AU - Kallenbach, Neville R.
N1 - Funding Information:
This work was supported by grant GB-29210 from the National Science Foun-
Funding Information:
dation, U.S.P.H.S. grants CA-06927 and RR-05539 from the National Institutes of Health, and by an appropriation from the Commonwealth of Pennsylvania. N.R.K. acknowledges a fellowship from the J. S. Guggenheim Memorial Foundation. Dr Toshio Nagata provided helpful data and discussion on his work as did Dr Thomas F. Anderson and Dr Manfred E. Bayer.
PY - 1977/2/21
Y1 - 1977/2/21
N2 - The process of DNA replication in procaryotes with a circular chromosome is analyzed in terms of a stochastic model including the following features: (1) heterogeneity in the rate of DNA synthesis from cell to cell in a culture, (2) any degree of positive or negative correlation between mother and daughter cells and (3) drift of the origin and terminus in a chromosome from one generation to the next over a specified region or set of points in the chromosome. The model is applied to experimental data on E. coli cells in balanced growth, assuming the bidirectional replication process can be simulated by independent unidirectional processes along each arm. Comparison of calculated recovery profiles for label in a density pulse experiment reveals that there is remarkable latitude for drift of the origin from one generation to the next, with succeeding rounds capable of initiation at any site within a region of one half the total chromosomal length. The marker frequencies of genes at different positions on the chromosome measured by "equilibrium" assays similarly can be reconciled with unidirectional or bidirectional processes with a wandering origin. If as is suggested by results from kinetic experiments on populations with aligned chromosomes replication is bidirectional with a unique fixed site of origin, the results of the label recovery experiments are inconsistent with the available evidence for heterogeneity in replication times and growth rates.
AB - The process of DNA replication in procaryotes with a circular chromosome is analyzed in terms of a stochastic model including the following features: (1) heterogeneity in the rate of DNA synthesis from cell to cell in a culture, (2) any degree of positive or negative correlation between mother and daughter cells and (3) drift of the origin and terminus in a chromosome from one generation to the next over a specified region or set of points in the chromosome. The model is applied to experimental data on E. coli cells in balanced growth, assuming the bidirectional replication process can be simulated by independent unidirectional processes along each arm. Comparison of calculated recovery profiles for label in a density pulse experiment reveals that there is remarkable latitude for drift of the origin from one generation to the next, with succeeding rounds capable of initiation at any site within a region of one half the total chromosomal length. The marker frequencies of genes at different positions on the chromosome measured by "equilibrium" assays similarly can be reconciled with unidirectional or bidirectional processes with a wandering origin. If as is suggested by results from kinetic experiments on populations with aligned chromosomes replication is bidirectional with a unique fixed site of origin, the results of the label recovery experiments are inconsistent with the available evidence for heterogeneity in replication times and growth rates.
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U2 - 10.1016/0022-5193(77)90273-9
DO - 10.1016/0022-5193(77)90273-9
M3 - Article
C2 - 321880
AN - SCOPUS:0017578485
SN - 0022-5193
VL - 64
SP - 747
EP - 760
JO - Journal of Theoretical Biology
JF - Journal of Theoretical Biology
IS - 4
ER -