Kinetoplastid Protozoans Flashcards
Kinetoplastid protozoans include?
Trypanosoma brucei
Trypanosoma cruzi
Leishmania
Kinetoplastid protozoans move via?
Flagella
Eukaryotic flagellum structure?
9+2 axoneme structure
9 microtubule pairs surrounding two central microtubules
Dynein motors cause the microtubules to slide past one another which causes the movement of the flagella
Where is the basal body located?
At the base of the flagellum
What is Trypanosoma cruzi also known as?
American trypanosome
What is Trypanosoma brucei also known as?
African trypanosome
Trypanosoma cruzi causes?
Chagas disease
Trypanosoma cruzi is spread by?
Kissing/Triatomine bugs
Trypanosoma brucei causes?
Sleeping sickness
Trypanosoma brucei is spread by?
Tsetse flies
Trypanosoma cruzi affects people in which part of the world?
Latin America
Trypanosoma brucei affects people in which part of the world?
Central African, Congo
Leishmania is spread by?
Sandflies
Leishmania causes?
Leishmaniasis
What is the flagellar pocket?
It is where the flagellum emerges
It is where endocytosis takes place
It is an invagination at the base of the flagellum
Many invariant surface receptors are located here as it is protected from the immune system, sheltered
Trypanosoma brucei infects which cells?
It does not, it is extracellular
Trypanosoma cruzi infects which cells?
Many different cell types
Trypanosoma cruzi replicates where?
In the cytosol
Which cells does Leishmania infect?
Macrophages
What do all kinetoplastid protozoa contain?
kDNA
Kinetoplast DNA
How many mitochondria are present in Kinetoplastid parasites?
Unlike most eukaryotic cells, kinetoplastid protozoa contain a single mitochondrion
What is the structure of the kDNA?
When condensed forms a disk
Made up of many concatenated DNA circles
Made up of minicircles and maxicircles
How large are the minicircles?
Around 1kb
How large are the maxicircles?
Around 20kb
What is the function of the minicircles?
Only known function is to produce gRNAs for RNA editing
What is the function of the maxicircles?
Similar size to mtDNA
Basically mtDNA
Produce mitochondrial rRNAs, cytochrome b, cytochrome oxidase subunits etc…
How does replication of minicircles occur?
1) Topoisomerase II releases minicircles from the central region of the disk. They are released from the disk into the kinetoflagellar zone (KFZ)
2) Migrate to the antipodal sites and replicate as they do so
3) Once the antipodal sites are reached they are attached to the network periphery adjacent to the antipodal sites via topoisomerase II
The replicated minicircles contain?
A nick/gap
What may be the function of the nick/gap?
To mark the minicircles as replicated, to ensure only a single round of replication occurs
When is the kDNA replicated?
When the flagella replicate
How is the replicated kDNA divided?
Attached to the basal body via filaments
kDNA is replicated as the flagellar system is duplicated
As the basal bodies move apart the kDNA is seperated
The minicircles are added to a moving?
A moving kDNA disk
Why is the kDNA disk moving?
To ensure equal distribution of replicated minicircles
What is the movement like in T.brucei?
Oscillation
What is the movement like in T.cruzi?
Spinning
Chemicals to inhibit kDNA replication could include?
Topoisomerase inhibitors
Or drugs to bind DNA
Why is RNA editing required?
As the genes of the maxicircles contain frameshift mutations
RNA editing involves the addition of deletion of?
Uridines
RNA editing is mediated by?
gRNAs produced by minicircles
gRNAs contian?
A 5’ anchor sequence which dictates the addition or deletion of uridines, a 3’ poly-U tail
