Fine mapping of replication origins (ori A and ori B) in Nicotiana tabacum chloroplast DNA. Nucleic Acids Res 1997 Sep 15;25(18):3681-6
Date
09/15/1997Pubmed ID
9278490Pubmed Central ID
PMC146947DOI
10.1093/nar/25.18.3681Scopus ID
2-s2.0-0030766634 (requires institutional sign-in at Scopus site) 71 CitationsAbstract
Using a partially purified replication complex from tobacco chloroplasts, replication origins have been localized to minimal sequences of 82 (pKN8, positions 137 683-137 764) and 243 bp (pKN3, positions 130 513-130 755) for ori A and ori B respectively. Analysis of in vitro replication products by two-dimensional agarose gel electrophoresis showed simple Y patterns for single ori sequence-containing clones, indicative of rolling circle replication. Double Y patterns were observed when a chloroplast DNA template containing both ori s (pKN9) was tested. Dpn I analysis and control assays with Escherichia coli DNA polymerase provide a clear method to distinguish between true replication and DNA repair synthesis. These controls also support the reliability of this in vitro chloroplast DNA replication system. EM analysis of in vitro replicated products showed rolling circle replication intermediates for single ori clones (ori A or ori B), whereas D loops were observed for a clone (pKN9) containing both ori s. The minimal ori regions contain sequences which are capable of forming stem-loop structures with relatively high free energy and other sequences which interact with specific protein(s) from the chloroplast replication fraction. Apparently the minimal ori sequences reported here contain all the necessary elements for support of chloroplast DNA replication in vitro.
Author List
Kunnimalaiyaan M, Nielsen BLMESH terms used to index this publication - Major topics in bold
Base SequenceChloroplasts
Chromosome Mapping
DNA, Chloroplast
Escherichia coli
Molecular Sequence Data
Plants, Toxic
Replication Origin
