Spore photoproduct lyase

There are several types of thymine cross linking, but SPL specifically targets 5-thyminyl-5,6-dihydrothymine, which is also called spore photoproduct (SP).

[5][6] This difference in conformation is believed to be the reason why dormant spores predominantly accumulate SP in response to UV-radiation, rather than other forms of cross linking.

The mechanism by which SPL functions is not yet fully understood,[8] though it is known that it catalyzes light independent repair[8] of photodimer 5-thyminyl-5,6-dihydrothymine cross linking through a series of radical reactions to give back two functional thymine rings[9][3] as shown in the figure below.

[8] Given that the full mechanism of SPL function is not fully characterized, future studies will likely focus on elucidation of this process.

[7] Spores exhibit high UV susceptibility only when both repair pathways are compromised.