Gene Proteins and Functions - E. coli DNA repair, BLM, Recombination, Forks

Question 1

RecG function

Answer 1

Unwinding strands during E. coli recombination to re-establish stalled forks

Question 2

RuvABC complex

Answer 2

Cleaving four stranded Holliday junction during E. coli recombination to re-establish stalled forks

Question 3

RecA - stalled forks

Answer 3

Assists strand invasion and homology search / D-loop formation in E. coli recombination to re-establish stalled forks, with RecBCD

Question 4

RecBCD - stalled forks

Answer 4

Assists strand invasion and homology search / D-loop formation in E. coli recombination to re-establish stalled forks, with RecA

Question 5

PriA

Answer 5

Loads DnaB and DnaG to reinitiate aborted replication fork in E. coli

Question 6

DnaB and DnaG

Answer 6

Proteins that are recruited to reinitiate aborted replication fork in E. coli - they are replication helicase and primase

Question 7

RecG

Answer 7

In E. coli, binds fork and spits out re-annealed daughter strands, generates chicken foot structure

Question 8

RecBCD - dsb repair

Answer 8

Processes dsb to generate 3’ overhangs

Question 9

RecA - dsb repair

Answer 9

Coats 3’ overhangs made by RecBCD to start homology search

Question 10

RuvAB

Answer 10

D-loop formation and branch migration in dsb repair

Question 11

RuvAC

Answer 11

Resolves double Holliday junction in dsb repair

Question 12

MMR machinery - dsb repair

Answer 12

Will fix heteroduplex mismatches, may or may not grab the parent strand; if wrong strand taken, gene conversion may occur

Question 13

BLM and TOPO III Alpha

Answer 13

Inwards branch migration and cutting, twisting, annealing to resolve dHJ without crossing over, aka, will instead form hemicatenane

Question 14

The three E. coli repair mechanisms

Answer 14

• Short patch repair
• MMR
• SOS

Question 15

Short patch repair process

Answer 15

• UvrAB attaches
• UvrA departs, replaced with UvrC
• UvrB cuts 5bp downstream
• UvrC cuts 8bp upstream
• Helicase removes segment
• DNA Pol I infills, ligase ligates

Question 16

MutS

Answer 16

Binds mismatch, recruits MutL and MutH, E. coli MMR

Question 17

MutL and MutH

Answer 17

Bring d(GATC) sequence close to mismatch, MutH nicks unmethylated strand, mismatch removed, E. coli MMR

Question 18

SOS response in E. coli

Answer 18

LexA is a transcriptional repressor binding the SOS box, RecA is stimulated by DNA damage which cleaves LexA to facilitate transcription of DNA damage repair genes