This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Meeker, R Articles by Tewari, K K Search for Related Content PubMed PubMed Citation Articles by Meeker, R Articles by Tewari, K K

 Previous Article  |  Next Article 

Mol Cell Biol. 1988 March; 8(3): 1216-1223

Localization of replication origins in pea chloroplast DNA.

R Meeker, B Nielsen and K K Tewari

Department of Molecular Biology and Biochemistry, University of California, Irvine 92717.

ABSTRACT

The locations of the two replication origins in pea chloroplast DNA (ctDNA) have been mapped by electron microscopic analysis of restriction digests of supercoiled ctDNA cross-linked with trioxalen. Both origins of replication, identified as displacement loops (D-loops), were present in the 44-kilobase-pair (kbp) SalI A fragment. The first D-loop was located at 9.0 kbp from the closest SalI restriction site. The average size of this D-loop was about 0.7 kbp. The second D-loop started 14.2 kbp in from the same restriction site and ended at about 15.5 kbp, giving it a size of about 1.3 kbp. The orientation of these two D-loops on the restriction map of pea ctDNA was determined by analyzing SmaI, PstI, and SalI-SmaI restriction digests of pea ctDNA. One D-loop has been mapped in the spacer region between the 16S and 23S rRNA genes. The second D-loop was located downstream of the 23S rRNA gene. Denaturation mapping of recombinants pCP 12-7 and pCB 1-12, which contain both D-loops, confirmed the location of the D-loops in the restriction map of pea ctDNA. Denaturation-mapping studies also showed that the two D-loops had different base compositions; the one closest to a SalI restriction site denatured readily compared with the other D-loop. The recombinants pCP 12-7 and pCB 1-12 were found to be highly active in DNA synthesis when used as templates in a partially purified replication system from pea chloroplasts. Analysis of in vitro-synthesized DNA with either of these recombinants showed that full-length template DNA was synthesized. Recombinants from other regions of the pea chloroplast genome showed no significant DNA synthesis activity in vitro.

---

Mol Cell Biol. 1988 March; 8(3): 1216-1223

This article has been cited by other articles:

• Tuteja, N., Phan, T.-N. (1998). A Chloroplast DNA Helicase II from Pea That Prefers Fork-Like Replication Structures. Plant Physiol. 118: 1029-1038 [Abstract] [Full Text]  
• Heinhorst, S, Cannon, G. (1993). DNA replication in chloroplasts. J. Cell Sci. 104: 1-9 [Abstract]