Open AccessMitochondrial minicircle DNA supports plasmid replication and maintenance in nuclei of Trypanosoma brucei.
Author(s) -
Stan Metzenberg,
Nina Agabian
Publication year - 1994
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.91.13.5962
Subject(s) - minicircle , kinetoplast , trypanosoma brucei , biology , concatemer , plasmid , extrachromosomal dna , mitochondrial dna , dna replication , dna , microbiology and biotechnology , population , genetics , gene , genome , demography , sociology
In a search for trypanosome DNA sequences that permit replication and stable maintenance of extrachromosomal elements, a 1-kilobase-pair (kbp) fragment from a mitochondrial kinetoplast DNA (kDNA) minicircle of Trypanosoma brucei was isolated and characterized. The plasmid pTbo-1, carrying the kDNA element, is maintained in T. brucei as a supercoiled concatemer containing approximately seven to nine pTbo-1 monomer units (5.6 kbp each) in a head-to-tail orientation. The concatemer is found in approximately one copy per cell when procyclic trypanosomes are cultured in the presence of 100 micrograms of hygromycin per ml; however, in the absence of continuous hygromycin selection, the plasmid is lost from the population with a t1/2 of approximately 8.7 days (17 cell generations). A second unrelated kDNA minicircle was also able to serve as an autonomously replicating sequence (ARS) element in T. brucei, suggesting that this is a general property of kDNA minicircles. Replication of mitochondrial DNA in the nucleus may be due to either a specific consensus sequence (such as in yeast ARS elements) or nonspecific sequence characteristics (such as the degree of A&T-richness or bent DNA).