Thylakoid-bound chloroplast DNA from spinach is enriched for replication forks.
Chloroplast DNA is bound to the thylakoids of spinach chloroplasts. To examine a possible role for thylakoid-bound DNA in chloroplast DNA replication, vesicles formed by treating chloroplasts in 3.5 mM MgCl2 were used. Chloroplast DNA fragments are bound to the surface of these vesicles. Chloroplast DNA isolated from vesicles that had been first treated with Eco R1 contained 10% of branched fragments whereas chloroplast DNA isolated from intact chloroplasts and treated with Eco R1 contained 2% of branched fragments. This result is consistent with the growing replication fork of chloroplast DNA being associated with the chloroplast internal membrane system. Branched fragments from the chloroplast DNA digested with Eco R1 prior to the isolation from the vesicle contained fragments of unequal length. Membrane binding in chloroplasts may have a similar role in DNA replication as it does in bacteria.
Lindbeck
A G
AG
Department of Biological Sciences, University of Newcastle, New South Wales, Australia.
Rose
R J
RJ
D002736:Chloroplasts / Q000378:metabolism*; D004247:DNA / Q000235:genetics* / Q000302:isolation & purification / Q000648:ultrastructure; D004261:DNA Replication; D008854:Microscopy, Electron; D010944:Plants / Q000378:metabolism*
D004247:DNA