TY - JOUR
T1 - Mitochondrial-like DNA sequences flanked by direct and inverted repeats in the nuclear genome of Toxoplasma gondii
AU - Ossorio, Pilar N.
AU - Sibley, L. David
AU - Boothroyd, John C.
N1 - Funding Information:
We thank Dr <Jean-Francois Dubremetz for communicating results prior to publication. We also thank Dr David Clayton and members of the Boothroyd laboratory for their helpful comments. This work was supported in part by grants from the NIH (A121423) and the John D. and Catherine T. MacArthur Foundation. J.C.B. is a Burroughs Wellcome Scholar in Molecular Parasitology. L.D.S. is support’ed in part by a grant from Merck, Sharp and Dohme and P.N.G. by an NIH predoctoral training grant (AI0732803).
PY - 1991/12/5
Y1 - 1991/12/5
N2 - In the course of our genetic studies on Toxoplasma gondii, it was discovered that one cosmid hybridized to a repetitive element. The hybridization pattern observed for the enzyme bglII indicated that this cosmid hybridized to a large number of discrete, but related, elements. Four bglII fragments were subcloned from the cosmid, and each was shown to hybridize with all the others, as well as to numerous dispersed sequences in genomic DNA. Three subclones were sequenced in their entirety, and shown to contain fragments of the genes for cytochrome oxidase subunit I and apocytochrome b, complete and functional copies of which have been found in only mitochondrial genomes. All the subcloned fragments were bounded at both ends by a 91 base-pair sequence, which contains a site for bglII. This 91 base-pair sequence could be found as either a direct or inverted repeat. It was determined that the bglII elements are arrayed downstream from a single copy nuclear gene. Comparison of genomic and cosmid DNAs confirmed that the cosmid faithfully reflects the nuclear genome. Although the mitochondrial genome of Toxoplasma has not been characterized, these nuclear mitochondrial-like sequences appear to be internally rearranged with respect to known, functional mitochondrial genomes, and with respect to each other. The finding of short repeated sequences flanking these elements may be a clue to the mechanism of their dissemination.
AB - In the course of our genetic studies on Toxoplasma gondii, it was discovered that one cosmid hybridized to a repetitive element. The hybridization pattern observed for the enzyme bglII indicated that this cosmid hybridized to a large number of discrete, but related, elements. Four bglII fragments were subcloned from the cosmid, and each was shown to hybridize with all the others, as well as to numerous dispersed sequences in genomic DNA. Three subclones were sequenced in their entirety, and shown to contain fragments of the genes for cytochrome oxidase subunit I and apocytochrome b, complete and functional copies of which have been found in only mitochondrial genomes. All the subcloned fragments were bounded at both ends by a 91 base-pair sequence, which contains a site for bglII. This 91 base-pair sequence could be found as either a direct or inverted repeat. It was determined that the bglII elements are arrayed downstream from a single copy nuclear gene. Comparison of genomic and cosmid DNAs confirmed that the cosmid faithfully reflects the nuclear genome. Although the mitochondrial genome of Toxoplasma has not been characterized, these nuclear mitochondrial-like sequences appear to be internally rearranged with respect to known, functional mitochondrial genomes, and with respect to each other. The finding of short repeated sequences flanking these elements may be a clue to the mechanism of their dissemination.
KW - Toxoplasma gondii
KW - cytochromes
KW - direct/inverted repeats
KW - gene transfer
KW - mitochondrial-like DNA
UR - http://www.scopus.com/inward/record.url?scp=0026344816&partnerID=8YFLogxK
U2 - 10.1016/0022-2836(91)90494-Q
DO - 10.1016/0022-2836(91)90494-Q
M3 - Article
C2 - 1660924
AN - SCOPUS:0026344816
SN - 0022-2836
VL - 222
SP - 525
EP - 536
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
IS - 3
ER -