title: A photolyase-like protein from Agrobacterium tumefaciens with an iron-sulfur cluster.
abstract: Photolyases and cryptochromes are evolutionarily related flavoproteins with distinct functions. While photolyases can repair UV-induced DNA lesions in a light-dependent manner, cryptochromes regulate growth, development and the circadian clock in plants and animals. Here we report about two photolyase-related proteins, named PhrA and PhrB, found in the phytopathogen Agrobacterium tumefaciens. PhrA belongs to the class III cyclobutane pyrimidine dimer (CPD) photolyases, the sister class of plant cryptochromes, while PhrB belongs to a new class represented in at least 350 bacterial organisms. Both proteins contain flavin adenine dinucleotide (FAD) as a primary catalytic cofactor, which is photoreduceable by blue light. Spectral analysis of PhrA confirmed the presence of 5,10-methenyltetrahydrofolate (MTHF) as antenna cofactor. PhrB comprises also an additional chromophore, absorbing in the short wavelength region but its spectrum is distinct from known antenna cofactors in other photolyases. Homology modeling suggests that PhrB contains an Fe-S cluster as cofactor which was confirmed by elemental analysis and EPR spectroscopy. According to protein sequence alignments the classical tryptophan photoreduction pathway is present in PhrA but absent in PhrB. Although PhrB is clearly distinguished from other photolyases including PhrA it is, like PhrA, required for in vivo photoreactivation. Moreover, PhrA can repair UV-induced DNA lesions in vitro. Thus, A. tumefaciens contains two photolyase homologs of which PhrB represents the first member of the cryptochrome/photolyase family (CPF) that contains an iron-sulfur cluster.
authors: Karlsruhe Institute of Technology, Botany I, Karlsruhe, Germany. inga.oberpichler@kit.edu
authors: Inga
authors: I
authors: Oberpichler
authors: Antonio J
authors: AJ
authors: Pierik
authors: Janine
authors: J
authors: Wesslowski
authors: Richard
authors: R
authors: Pokorny
authors: Ran
authors: R
authors: Rosen
authors: Michal
authors: M
authors: Vugman
authors: Fan
authors: F
authors: Zhang
authors: Olivia
authors: O
authors: Neubauer
authors: Eliora Z
authors: EZ
authors: Ron
authors: Alfred
authors: A
authors: Batschauer
authors: Tilman
authors: T
authors: Lamparter
mesh_terms: D016960:Agrobacterium tumefaciens / Q000201:enzymology* / Q000528:radiation effects; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage; D004260:DNA Repair / Q000528:radiation effects; D004251:DNA Transposable Elements / Q000235:genetics; D004255:Deoxyribodipyrimidine Photo-Lyase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010084:Oxidation-Reduction / Q000528:radiation effects; D010802:Phylogeny; D011740:Pyrimidine Dimers / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D040681:Structural Homology, Protein; D014466:Ultraviolet Rays
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D007506:Iron-Sulfur Proteins; D011740:Pyrimidine Dimers; D004255:Deoxyribodipyrimidine Photo-Lyase