Replication_Lecture3 - Manel Camps Flashcards
(14 cards)
Ter Sites
Sites 180degrees from OriC where replication is terminated. Block replication machinery in only one direction.
Tus
Protein that binds Ter sites and inhibits DnaB (helicase). Blocks in an orientation dependent manner.
True or False. Co-directional collisions impair replication fork progression.
False
True or False. Head-on collisions result in replication fork arrest.
True
True or False. Most essential genes are on the leading strand.
True
DnaA
Important for replication initiation. Metabolic control of replication initiation occurs at the level of DnaA.
ppGpp
An alarmone that is produced during stressful events (amino acid starvation, carbon starvation, fatty-acid limitation).
Created when 2 phosphates from ATP are added to GTP.
Binds directly to RNAP and increases decay of open complex. through the “magic spot.”
Inhibits replication elongation through DnaG/Primase inhibition.
SpoT
Can catalyze the formation of ppGpp in response to limiting phosphate, carbon, iron, fatty acid conditions as well as osmotic shock.
Can also degrade ppGpp (bifunctional protein).
RelA
Can catalyze the production of ppGpp in response to limiting AA.
Ribonucleotide Reductase (RNR)
A protein that synthesizes and balances pools of dNTPs.
RNR A-Site
Activity site that turns enzyme on and off. Turned off by very high amounts of dNTPs.
RNR S-Site
Specificity site. Determines which substrates are reduced at the catalytic site. Important for dNTP balance.
nrdAB
Genes activated in response to replication problems as well as at the initiation of DNA replication.
Low levels of DnaA activate expression while low levels inhibit expression.
MutSLH
A DNA repair system that recognizes mismatch repair. Facilitates strand excision and repair.
