Deoxyribodipyrimidine photo-lyase

Deoxyribodipyrimidine photo-lyase (also known as DNA photolyase) is an enzyme that repairs DNA damage caused by exposure to ultraviolet light. This enzyme is part of the nucleotide excision repair pathway, which is a critical mechanism for maintaining the integrity of the genome.

Function

Deoxyribodipyrimidine photo-lyase is a flavoprotein that uses energy from visible light to break the covalent bonds between adjacent pyrimidine bases in DNA that have become cross-linked by exposure to ultraviolet light. This type of DNA damage, known as a pyrimidine dimer, distorts the DNA helix and can block DNA replication or transcription.

The enzyme binds to the damaged site in the DNA and absorbs a photon of light. This energy is transferred to the flavin adenine dinucleotide (FAD) cofactor, which then breaks the bonds of the pyrimidine dimer. The repaired DNA is then released by the enzyme.

Distribution

Deoxyribodipyrimidine photo-lyase is found in many organisms, including bacteria, yeast, and plants. However, it is not present in mammals, which instead rely on a more complex and less efficient repair mechanism known as nucleotide excision repair.

Clinical significance

Defects in DNA repair mechanisms, including the action of deoxyribodipyrimidine photo-lyase, can lead to a variety of diseases, including xeroderma pigmentosum, a condition characterized by extreme sensitivity to sunlight and a high risk of skin cancer.

See also

• Photoreactivation
• DNA repair
• Xeroderma pigmentosum