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A comparative study of xanthine dehydrogenase regulator proteins in Agrobacterium tumefaciens and Streptomyces coelicolor (946.3)
Author(s) -
Sivapragasam Smitha,
Grove Anne
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.946.3
Subject(s) - streptomyces coelicolor , xanthine dehydrogenase , agrobacterium tumefaciens , hypoxanthine , xanthine , gene cluster , dehydrogenase , purine , biochemistry , chemistry , cumene hydroperoxide , microbiology and biotechnology , dna , gene , biology , enzyme , xanthine oxidase , transformation (genetics) , mutant , catalysis
A. tumefaciens and S. coelicolor are among the most studied bacteria with the former being the 3 rd most important plant pathogen. The transcription factor XdhR of S. coelicolor (ScXdhR) regulates its own gene expression along with the divergently oriented xanthine dehydrogenase ABC ( xdh ) gene cluster. A similar genomic locus was observed in A. tumefaciens . Xanthine dehydrogenase converts hypoxanthine and xanthine to urate. Based on elecrophoretic mobility shift assays we show that ScXdhR and XdhR of A. tumefaciens (AtXdhR) bound to their respective intergenic regions specifically but with different binding affinities. The ligands GMP, rGTP and xanthine compromised the DNA‐XdhR binding in both cases. The ScXdhR‐DNA complex also dissociated upon addition of H 2 O 2 , cumene hydroperoxide and tert‐butyl hydroperoxide, whereas DNA binding by AtXdhR was unaffected. SDS‐PAGE analysis revealed that ScXdhR dimerized upon addition of these oxidants, whereas AtXdhR did not. AtXdhR dimerized in the presence of Co 2+ whereas ScXdhR did so in the presence of Cu 2+ as well as Co 2+ . This study suggests that both XdhR proteins may regulate expression of the xdh gene cluster in response to intermediates in the purine degradation pathway. Notably, ScXdhR also responds to oxidation, suggesting upregulation of xdh during oxidative stress. Grant Funding Source : NSF