Kinetoplast

Kinetoplastida or Kinetoplasteaas kinetoplast class is a group of flagellated protists belonging to the phylum Euglenozoa[3] [4] and characterised by the presence of a distinctive organelle called the kinetoplast hence the namea granule containing a large mass of DNA, kinetoplast. The group includes a number of parasites responsible for serious diseases in humans and other animals, kinetoplast, as well as various forms found kinetoplast soil and aquatic environments.

Federal government websites often end in. The site is secure. The kinetoplast is a specialized region of the mitochondria of trypanosomatids that harbors the most complex and unusual mitochondrial DNA found in nature. Kinetoplast DNA kDNA is composed of thousands of circular molecules topologically interlocked to form a single network. Two types of DNA circles are present in the kinetoplast: minicircles 0. Knowledge of kinetoplast architecture is crucial to understanding the replication and segregation of kDNA circles because the molecules involved in these processes are precisely positioned in functional domains throughout the kinetoplast.

Kinetoplast

This page has been archived and is no longer updated. Kinetoplastids are flagellated protozoans, which are unicellular eukaryotic organisms. They include free-living microorganisms, as well as parasites of diverse invertebrate, vertebrate, and plant species. Some kinetoplastids are responsible for serious human diseases, such as Chagas disease and sleeping sickness caused by Trypanosoma cruzi and Trypanosoma brucei , respectively , and the various forms of cutaneous and visceral leishmaniasis caused by Leishmania spp. The network of rings in kDNA forms a beautiful structure. Observed under the electron microscope, it resembles the chainmail that medieval knights wore under their plate armor for protection. In their research on kDNA, scientists eager to understand the function of this amazing structure made a second unexpected discovery: a novel, complex mechanism for RNA processing of mitochondrial transcripts, now known as RNA editing. Investigators from different disciplines have been working hard over the past decades to gather clues to explain the unusual properties of kDNA. Today there are still many questions left to answer. The first tools developed for the study of cells and tissues were optical microscopes.

Poly-kDNA has been observed in Dimastigella trypaniformis a commensal in kinetoplast intestine of a termiteDismastigella mimosa a free-living kinetoplastidand Cruzella marina a parasite of the intestine of a sea squirt, kinetoplast. The chondriome of selected trypanosomatids, kinetoplast.

Federal government websites often end in. The site is secure. Unique to the single mitochondrion of unicellular flagellates of the order Kinetoplastida, kDNA is best known as a giant network of thousands of catenated circular DNAs an electron micrograph of a network is shown in Fig. The kDNA circles are of two types, maxicircles and minicircles. Maxicircles usually range from 20 to 40 kb, depending on the species, and are present in a few dozen identical copies per network.

Federal government websites often end in. The site is secure. Unique to the single mitochondrion of unicellular flagellates of the order Kinetoplastida, kDNA is best known as a giant network of thousands of catenated circular DNAs an electron micrograph of a network is shown in Fig. The kDNA circles are of two types, maxicircles and minicircles. Maxicircles usually range from 20 to 40 kb, depending on the species, and are present in a few dozen identical copies per network. Minicircles, present in several thousand copies per network, are usually nearly identical in size 0. Maxicircles encode typical mitochondrial gene products e. To generate functional mRNAs, the cryptic maxicircle transcripts undergo posttranscriptional modification via an intricate RNA editing process that involves insertion and deletion of uridine residues at specific sites in the transcripts.

Kinetoplast

Understanding the self-assembly and replication of this structure are not only major open questions in biology but can also inform the design of synthetic topological materials. Here, we report the first high-resolution, single-molecule study of kDNA network topology using AFM and steered molecular dynamics simulations. We map out the DNA density within the network and the distribution of linking number and valence of the minicircles. We also characterize the DNA hubs that surround the network and show that they cause a buckling transition akin to that of a 2D elastic thermal sheet in the bulk. Intriguingly, we observe a broad distribution of density and valence of the minicircles, indicating heterogeneous network structure and individualism of different kDNA structures. Finally, we estimate the 2D Young modulus of the network to be orders of magnitude smaller than that of other 2D materials. Our findings explain outstanding questions in the field and offer single-molecule insights into the properties of a unique topological material. Pinyao He 1,2 , Allard J.

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Email your Friend. Figure 7. These discoveries provided further support for RNA editing. A problem, of course, is T. Both catenanes are extensively linked with one another to form a complicated kDNA network or "network within a network" Shapiro Ribonucleotides associated with a gap in newly replicated kinetoplast DNA minicircles from Trypanosoma equiperdum. Robinson and P. RNA 2 : Nucleotide sequences provide evidence of genetic exchange among distantly related lineages of Trypanosoma cruzi. II Section through a condensed network disk in vivo showing stretched-out minicircles.

Situated near the nucleus, kinetoplasts are made up of a dense structure consisting of DNA kDNA within the mitochondria. As an extranuclear bundle of DNA, kinetoplast are distinguishing features among some eukaryotes that are collectively known as kinetoplastids members of the order Kinetoplastida. Based on molecular studies, kinetoplasts have been shown to contain two types of circular DNA.

Figure 6 Figure Detail As they began to study the transcription of the kDNA genes, investigators found to their dismay that many of the protein-coding genes appeared to be nonfunctional. The kinetoflagellar zone and the antipodal sites are domains involved in the early and late steps of kDNA replication, respectively. Federal government websites often end in. Critical point mounting of kinetoplast DNA for atomic force microscopy. The comparative analyses of epimastigote and trypomastigote highlighted interesting differences in the topology of kDNA. It is interesting to point out that in the middle of the network, the height varied from 0. Pharyngomonadida Pharyngomonadidae. Whitaker, and A. Margulis Robinson, M. Danielle Pereira Cavalcanti 1 , 2 and Wanderley de Souza 2 , 3. For example, there is a price to pay for abandoning supercoiling. Zuma A. London Ser.