Final answer:
UvrA recognizes a DNA damage site and begins the nucleotide excision repair process by forming a complex with UvrB and UvrC to remove the damaged segment, ensuring genomic stability.
Step-by-step explanation:
What Happens When UvrA Recognizes a Damage Site?
When UvrA recognizes a damage site on DNA, it initiates the nucleotide excision repair (NER) process. NER is critical for repairing bulky, helix-distorting lesions like thymine dimers and other forms of UV damage that can result in abnormalities in the DNA structure. UvrA, along with UvrB and UvrC, forms the UvrABC endonuclease complex. This complex detects the DNA damage and acts to remove the damaged DNA segment. Subsequently, DNA polymerase fills in the missing nucleotides, and DNA ligase seals the strand. This repair mechanism is vital for preserving the integrity of the genetic information and preventing mutations that could potentially lead to diseases such as cancer.
UvrA's role specifically is to bind to the DNA at the site of damage and, with the help of ATP energy, change conformation to activate the recruitment of UvrB. Together, UvrA and UvrB will then locate UvrC, which cuts the damaged DNA strand at positions flanking the lesion. The collaboration of these molecules ensures that errors induced by environmental factors such as UV radiation are corrected, maintaining genomic stability.