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===Kinetoplast Structure=== |
===Kinetoplast Structure=== |
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The kinetoplast contains circular DNA in two forms - minicircles and maxicircles. Maxicircles are between 20 and 40kb in size and there are a few dozen per kinetoplast. There are several thousand minicircles per kinetoplast and these are between 0.5 and 1kb in size. The maxicircles encode the typical protein products needed for the mitochondria which is encrypted. Herein lies the only known function of the minicircles - producing guide RNA (gRNA) to decode this encrypted maxicircle information, typically through the insertion or deletion of [[uridine]] residues. The network of maxicircles and minicircles are [[catenation |catenated]] to form a planar network that resembles chain mail in medieval armor. Reproduction of this network then requires that these rings be disconnected from the parental kinetoplast and subsequently reconnected in the daughter kinetoplast. This unique mode of DNA replication may represent potential drug targets. <ref> Unique characteristics of the kinetoplast DNA replication machinery provide potential drug targets in trypanosomatids. </ref> |
The kinetoplast contains circular DNA in two forms - minicircles and maxicircles. Maxicircles are between 20 and 40kb in size and there are a few dozen per kinetoplast. There are several thousand minicircles per kinetoplast and these are between 0.5 and 1kb in size. The maxicircles encode the typical protein products needed for the mitochondria which is encrypted. Herein lies the only known function of the minicircles - producing guide RNA (gRNA) to decode this encrypted maxicircle information, typically through the insertion or deletion of [[uridine]] residues. The network of maxicircles and minicircles are [[catenation |catenated]] to form a planar network that resembles chain mail in medieval armor. Reproduction of this network then requires that these rings be disconnected from the parental kinetoplast and subsequently reconnected in the daughter kinetoplast.<ref>{{cite book |author=Torri A. et al |title=Kinetoplast DNA Replication |book=DNA Replication in Eukaryotic Cells |publisher= Cold Spring Harbor Laboratory Press |pages=1029-1042 |year=1996 |ISBN=0-87969-459-9}}</ref> This unique mode of DNA replication may represent potential drug targets. <ref> Unique characteristics of the kinetoplast DNA replication machinery provide potential drug targets in trypanosomatids. </ref> |
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The best studied kDNA structure is that of [[Crithidia fasciculata]]: a catenated disk of circular kDNA maxicircles and minicircles, most of which are supercoiled. Exterior to the kDNA disk but directly adjacent are two complexes of proteins situated 180˚ from each other and are involved in minicircle replication. |
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==References== |
==References== |
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{{reflist}} |
{{reflist}} |
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Revision as of 18:31, 5 April 2012
A kinetoplast is a network of circular DNA (called kDNA) inside a large mitochondrion that contains many copies of the mitochondrial genome.[1][2] The most common kinetoplast structure is that of a disk, but has been observed in other arrangements. Kinetoplasts are only found in protozoa of the class Kinetoplastida. The varyation in the structures of kinetoplasts may reflect phylogenic relationships between Kinetoplastids. [3] Kinetoplasts are usually adjacent to the organisms' flagellar basal body leading to the thought that they are tightly bound to the cytoskeleton.
Trypanosoma
In Trypanosomes, a group of flagellated protozoans, the kinetoplast exists as a dense granule of DNA within the large mitochondrion. Trypanosoma brucei, the parasite which causes African trypanosomiasis (African sleeping sickness), is an example of a trypanosome with a kinetoplast. Its kinetoplast is easily visible in samples stained with DAPI, a fluorescent DNA stain, or by the use of fluorescent in situ hybridization (FISH) with BrdU, a thymidine analogue.[4]
Kinetoplast Structure
The kinetoplast contains circular DNA in two forms - minicircles and maxicircles. Maxicircles are between 20 and 40kb in size and there are a few dozen per kinetoplast. There are several thousand minicircles per kinetoplast and these are between 0.5 and 1kb in size. The maxicircles encode the typical protein products needed for the mitochondria which is encrypted. Herein lies the only known function of the minicircles - producing guide RNA (gRNA) to decode this encrypted maxicircle information, typically through the insertion or deletion of uridine residues. The network of maxicircles and minicircles are catenated to form a planar network that resembles chain mail in medieval armor. Reproduction of this network then requires that these rings be disconnected from the parental kinetoplast and subsequently reconnected in the daughter kinetoplast.[5] This unique mode of DNA replication may represent potential drug targets. [6]
The best studied kDNA structure is that of Crithidia fasciculata: a catenated disk of circular kDNA maxicircles and minicircles, most of which are supercoiled. Exterior to the kDNA disk but directly adjacent are two complexes of proteins situated 180˚ from each other and are involved in minicircle replication.
References
- ^ Shapiro TA, Englund PT (1995). "The structure and replication of kinetoplast DNA". Annu. Rev. Microbiol. 49: 117–43. doi:10.1146/annurev.mi.49.100195.001001. PMID 8561456.
- ^ Shlomai J (2004). "The structure and replication of kinetoplast DNA". Curr. Mol. Med. 4 (6): 623–47. doi:10.2174/1566524043360096. PMID 15357213.
- ^ Lukes J.; et al. (2002). "Kinetoplast DNA Network: Evolution of an Improbable Structure". Eukaryotic Cell. 1: 495–502. doi:10.1128/EC.1.4.495-502.2002.
{{cite journal}}: Explicit use of et al. in:|author=(help); zero width space character in|doi=at position 9 (help) - ^ Gluenz E.; et al. (2011). "The kinetoplast replication cycle in Trypanosoma brucei is orchestrated by cytoskeleton-mediated cell morphogenesis". Molecular Cell Biology. 31 (5): 1012–1021. doi:10.1128/MCB.01176-10.
{{cite journal}}: Explicit use of et al. in:|author=(help); Unknown parameter|month=ignored (help) - ^ Torri A.; et al. (1996). Kinetoplast DNA Replication. Cold Spring Harbor Laboratory Press. pp. 1029–1042. ISBN 0-87969-459-9.
{{cite book}}: Explicit use of et al. in:|author=(help); Unknown parameter|book=ignored (help) - ^ Unique characteristics of the kinetoplast DNA replication machinery provide potential drug targets in trypanosomatids.
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