14 DNA damage

methyl directed mismath repair

distinguish template strand from newly synthesized strand

new strand is the strand that is not methylated immediately after replication

mutS

scans DNA and bind mismatch

mutH

fins the nearest methylated GATC sequence and nicks unmethylated strand

bind to mutS with MutL

Nucleotide excision repair (NER)

General repair pathway; repairs damage that cause a DNA distortion that identifies which strand is damaged

UvrD

unwinds DNA from the nick to MutSL bound site

UvrA2-UrvB complex

binds DNA nonspecifically

Scans for distortion

NER

UvrB/C

 nick damage strand on either side of damage in NER

uvrD

unwinds between the nicks, removing 12 nt from ssDNA

SOS response

Global DNA repair to extensive DNA damage

LexA

repressed expression of SOS

cleaved by recA* to being expression of SOS genes

Error prone SOS repair

extensive damage reponse

umuDC operon

photoactivation repair

directly repair the lesion by cleaving the abnormal bond formed from UV light

photolyase

enzyme that recognizes the DNA distortion caused by pyrimidine dimer

light cutting

Uses energy from light to cleave the abnormal bonds in the dimer, directly reversing the damage