The supply of exogenous deoxyribonucleotides accelerates the speed of the replication fork in early S-phase.
Earlier studies have established that the average speed of a replication fork is two to three times slower in early S-phase than in late S-phase and that the intracellular 2'-deoxyribonucleoside 5'-triphosphate pools grow during S-phase. In this study, the effect of the exogenous 2'-deoxyribonucleoside 5'-triphosphate (dNTP) supply on the average replication speed in a synchronised population of human HeLa cells was tested. The speed of replication fork movement was measured on extended DNA fibers labelled with 2'-deoxythymidine analogues 5-chloro-2'-deoxyuridine and 5-iodo-2'-deoxyuridine. We show that the introduction of exogenous dNTPs accelerates the replication process at the beginning of DNA synthesis only. In late S-phase, the administration of additional dNTPs has no effect on the speed of replication forks. The availability of 2'-deoxynucleotides seems to be a rate-limiting factor for DNA replication during early S-phase.
Malínsky
J
J
Department of Cell Biology, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Albertov 4, 128 00 Prague 2, Czech Republic.
Koberna
K
K
Stanĕk
D
D
Masata
M
M
Votruba
I
I
Raska
I
I
D004261:DNA Replication / Q000187:drug effects*; D003854:Deoxyribonucleotides / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008856:Microscopy, Fluorescence; D016196:S Phase / Q000187:drug effects*
D003854:Deoxyribonucleotides