44403
Description
Mind Map by jessica.woodward, updated more than 1 year ago
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Created by jessica.woodward
almost 12 years ago
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Topoisomerase
- Immunodepletion and antibody blocking
showed topo II activity required for chr.
assembly and condensation
- once condensation completed, topo II no
longer required - blocking had no effect
- Topo II molecules easily extracted from
chr. under MILD conditions
- Morphology of chr. well preserved
- mAb, MPM-2 (recognizes mitosis-specific
phosphoproteins) resistant to the same
treatment
- Morphology of chr. well preserved
- Localization:
Immunofluorescence showed
topo II uniformly distributed
throughout condensed chr.
NOT just axis
- Topo II molecules easily extracted from
chr. under MILD conditions
- Chr. organization and axial
structures are maintained
after topo II extraction
- => topo II doesn't play a
scaffolding role in the
structural maintenance of
mitotic chromosomes
- chr. scaffold = framework structure of nonhistone proteins that organize chromatin loops in mitotic
chromosomes
- chr. scaffold = framework structure of nonhistone proteins that organize chromatin loops in mitotic
chromosomes
- => topo II doesn't play a
scaffolding role in the
structural maintenance of
mitotic chromosomes
- once condensation completed, topo II no
longer required - blocking had no effect
- Topo II = enzyme that catalyzes strand passing of double stranded DNA
- Type II topoisomerases cut both strands of the DNA helix simultaneously in order to manage DNA tangles and supercoils. They use the hydrolysis of ATP.
- Topo II required for the individualization of chromosomes
in vertebrates, and for disentangling replicated sister
chromosomes in all oganisms
- Topo II required for the individualization of chromosomes
in vertebrates, and for disentangling replicated sister
chromosomes in all oganisms
- All eukaryotic cells have at least one type II topoisomerase
- Vertebrates have 2 isoforms: topo IIa
and topo IIb, with distinct localization
patterns in vivo
- During mitosis, topo IIa is enriched on
chromosomes, whereas topo IIb is
mostly cytoplasmic
- During mitosis, topo IIa is enriched on
chromosomes, whereas topo IIb is
mostly cytoplasmic
- Vertebrates have 2 isoforms: topo IIa
and topo IIb, with distinct localization
patterns in vivo
- Type II topoisomerases cut both strands of the DNA helix simultaneously in order to manage DNA tangles and supercoils. They use the hydrolysis of ATP.
- Topo I
- 13S condensin (I) is able to introduce +ve
supercoils into a closed circular DNA with the
help of bacterial/eukaryotic topo I
- reaction is ATP dependent
- reaction is ATP dependent
- 13S condensin (I) is able to introduce +ve
supercoils into a closed circular DNA with the
help of bacterial/eukaryotic topo I
- supercoiling
- Topo II
- Right-handed knots into
circular nicked plasmids
- Right-handed knots into
circular nicked plasmids
- Topo II
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