Kinetoplastid flagellates are known for several unusual features, one of which is their complex mitochondrial genome, known as kinetoplast (k) DNA, composed of mutually catenated maxi- and minicircles. Trypanosoma lewisi is a member of the Stercorarian group of trypanosomes which is, based on human infections and experimental data, now considered a zoonotic pathogen. By assembling a total of 58 minicircle classes, which fall into two distinct categories, we describe a novel type of kDNA organization in T. lewisi. RNA-seq approaches allowed us to map the details of uridine insertion and deletion editing events upon the kDNA transcriptome. Moreover, sequencing of small RNA molecules enabled the identification of 169 unique guide (g) RNA genes, with two differently organized minicircle categories both encoding essential gRNAs. The unprecedented organization of minicircles and gRNAs in T. lewisi broadens our knowledge of the structure and expression of the mitochondrial genomes of these human and animal pathogens. Finally, a scenario describing the evolution of minicircles is presented.

• MeSH
• adenosintrifosfatasy genetika   MeSH
• editace RNA MeSH
• fylogeneze MeSH
• genom mitochondriální MeSH
• guide RNA, Kinetoplastida genetika   MeSH
• mitochondrie genetika   MeSH
• podjednotky proteinů genetika   MeSH
• protozoální DNA genetika   MeSH
• RNA protozoální genetika   MeSH
• Trypanosoma lewisi genetika   MeSH
• vysoce účinné nukleotidové sekvenování MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adenosintrifosfatasy MeSH
• guide RNA, Kinetoplastida MeSH
• podjednotky proteinů MeSH
• protozoální DNA MeSH
• RNA protozoální MeSH

The mitochondrial DNA of diplonemid and kinetoplastid protists is known for its suite of bizarre features, including the presence of concatenated circular molecules, extensive trans-splicing and various forms of RNA editing. Here we report on the existence of another remarkable characteristic: hyper-inflated DNA content. We estimated the total amount of mitochondrial DNA in four kinetoplastid species (Trypanosoma brucei, Trypanoplasma borreli, Cryptobia helicis, and Perkinsela sp.) and the diplonemid Diplonema papillatum. Staining with 4',6-diamidino-2-phenylindole and RedDot1 followed by color deconvolution and quantification revealed massive inflation in the total amount of DNA in their organelles. This was further confirmed by electron microscopy. The most extreme case is the ∼260 Mbp of DNA in the mitochondrion of Diplonema, which greatly exceeds that in its nucleus; this is, to our knowledge, the largest amount of DNA described in any organelle. Perkinsela sp. has a total mitochondrial DNA content ~6.6× greater than its nuclear genome. This mass of DNA occupies most of the volume of the Perkinsela cell, despite the fact that it contains only six protein-coding genes. Why so much DNA? We propose that these bloated mitochondrial DNAs accumulated by a ratchet-like process. Despite their excessive nature, the synthesis and maintenance of these mtDNAs must incur a relatively low cost, considering that diplonemids are one of the most ubiquitous and speciose protist groups in the ocean. © 2018 IUBMB Life, 70(12):1267-1274, 2018.

• Klíčová slova
• DNA content, kinetoplast DNA, mitochondrial DNA, protist,
• MeSH
• Euglenozoa genetika   MeSH
• fylogeneze MeSH
• Kinetoplastida genetika   MeSH
• mitochondriální DNA genetika   izolace a purifikace   ultrastruktura   MeSH
• mitochondrie genetika   MeSH
• trans-splicing genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• mitochondriální DNA MeSH

Kinetoplastids are flagellated protozoans, whose members include the pathogens Trypanosoma brucei, T. cruzi and Leishmania species, that are considered among the earliest diverging eukaryotes with a mitochondrion. This organelle has become famous because of its many unusual properties, which are unique to the order Kinetoplastida, including an extensive kinetoplast DNA network and U-insertion/deletion type RNA editing of its mitochondrial transcripts. In the last decade, considerable progress has been made in elucidating the complex machinery of RNA editing. Moreover, our understanding of the structure and replication of kinetoplast DNA has also dramatically improved. Much less however, is known, about the developmental regulation of RNA editing, its integration with other RNA maturation processes, stability of mitochondrial mRNAs, or evolution of the editing process itself. Yet the profusion of genomic data recently made available by sequencing consortia, in combination with methods of reverse genetics, hold promise in understanding the complexity of this exciting organelle, knowledge of which may enable us to fight these often medically important protozoans.

• MeSH
• editace RNA MeSH
• exprese genu MeSH
• genetická transkripce MeSH
• genom protozoální * MeSH
• Kinetoplastida genetika   MeSH
• kinetoplastová DNA chemie   MeSH
• messenger RNA metabolismus   MeSH
• mitochondriální geny * MeSH
• mitochondrie genetika   MeSH
• RNA protozoální metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• kinetoplastová DNA MeSH
• messenger RNA MeSH
• RNA protozoální MeSH

• MeSH
• biologická evoluce MeSH
• Crithidia fasciculata genetika   ultrastruktura   MeSH
• elektronová mikroskopie MeSH
• fylogeneze MeSH
• Kinetoplastida genetika   ultrastruktura   MeSH
• kinetoplastová DNA genetika   ultrastruktura   MeSH
• Trypanosoma genetika   ultrastruktura   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Research Support, U.S. Gov't, P.H.S. MeSH
• Názvy látek
• kinetoplastová DNA MeSH