A COMPREHENSIVE PHYLOGENETIC STUDY REVEALS THE EXISTENCE OF BIFUNCTIONAL PHOTOLYASES IN PHOTOSYNTHETIC BACTERIA

FERNÁNDEZ, MB; CASSIA, RO

Congreso; RAFV 2021; 2021

Photolyases are flavoenzymes from the cryptochrome/ photolyase family (CPF). They repair DNAdamage induced by ultraviolet- B radiation in a blue and UV-A light driven mechanism. Photolyasesare specific for the repair of cyclobutane pyrimidine dimers (CPD), the major UV-B damage, andpyrimidine-pyrimidone (6?4) photoproducts (6?4PP). The first bifunctional photolyase, that repairboth types of damages, was recently reported in the antartic bacteria Sphingomonas sp SV9. Weperformed BlastP analysis to determine if this enzyme would be present in other species. All theretrieved sequences corresponded to bacteria proteins and matched the criteria of E- values lowerthan 0.001 (being lower to 1x10-63) and percentage identities higher than 30%. Subsequently, bothpartial sequences and those with percentage identities below 85% were identified and discarded.Then, we performed multiple sequence alignment (MSA), alignment curation and phylogenetic treeinference. These analysis revealed that over a total of 149 sequences, 55 were predicted asbifunctional photolyases. MSA analysis showed conservation of tryptophan´s important for electrontransfer required for lesion repair in the predicted bifunctional photolyases. It was also observedthat aminoacids involved in FAD and DNA lesion binding were conserved. A widespread distributionof bifunctional photolyases was observed among bacteria, including different genus fromproteobacteria, planctomycete, bacteroidetes, acidobacteria and cyanobacteria. The latter are theonly photosynthetic organisms encoding this enzyme. Finally, phylogenetic analysis including 6-4PP,CPD and bifunctional photolyases and other members from the CPF demonstrated that bifunctionalenzymes may represent a transition from 6-4PP to CPD specific photolyases.Financial support: This work is financially supported by ANPCyT PICT 2019 N° 1577 (to MBF) and2019 N° 3436 (to RC). MBF and RC are permanent researchers from CONICET.