Lecture 4 - Destroying The Eukaryotic Replisome Flashcards
What is the replisome?
A large molecular machine that copies chromosomes
Assembly and disassembly of the replisome is highly regulated to ensure that each chromosome is copied just BLANK
Assembly and disassembly of the replisome is highly regulated to ensure that each chromosome is copied just once
The replisome is built around a very stable core, what is it, and what is it composed of?
The CMG Helicase:
- Cdc45
- GINS
- Mcm2-7 (Forms hexameric ring, encircles one DNA strand)
Assembly of the BLANK is the key regulated step during the initiation of chromosome replication
Assembly of the CMG helicase is the key regulated step during the initiation of chromosome replication
The Mcm2-7 ring is topologically trapped around fork DNA and must never be displaced throughout elongation
TRUE OR FALSE
TRUE
How is CMG helicase removed from chromatin?
CMG helicase is rapidly disassembled during DNA replication termination
Work with budding yeast showed that CMG disassembly requires…?
Work with budding yeast showed that CMG disassembly requires a ubiquitin ligase (SCF^DIA2 [In yeast]) and the Cdc48/p97 ATPase (Yeast/Mammals respectively)
The Pif1-family of DNA helicases helps to unwind the BLANK when forks converge during DNA replication termination
The Pif1-family of DNA helicases helps to unwind the final stretch of parental DNA when forks converge during DNA replication termination
Replisome biology has been very poorly conserved during eukaryotic evolution.
TRUE OR FALSE
FALSE
Replisome biology has been very HIGHLY conserved during eukaryotic evolution.
Therefore yeast are great to study the replisome!
Despite high conservation of replisome biology in eukaryotes, SCF^DIA2 is only found in yeast
However, proteins with analogous roles exist…
CUL2^LRR1 drives CMG ubiquitination in C.elegans and X.laevis
The TRAIP ubiquitin ligase drives BLANK at sites of BLANK when C.elegans embryos or X.laevis egg extracts enter mitosis.
TRAIP also drives CMG disassembly when BLANKS converge at an inter-strand DNA crosslink in xenopus egg extracts.
The TRAIP ubiquitin ligase drives CMG disassembly at sites of incomplete replication when C.elegans embryos or X.laevis egg extracts enter mitosis.
TRAIP also drives CMG disassembly when 2 replication forks converge at an inter-strand DNA crosslink in xenopus egg extracts.
