Resonance Raman Spectroscopic Investigation of the Light-Harvesting Chromophore in Escherichia coli Photolyase and Vibrio cholerae Cryptochrome-1

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• 作者：Olga Sokolova ; Christine Cecala ; Anand Gopal ; Frank Cortazar ; Carla McDowell-Buchanan ; Aziz Sancar ; Yvonne M. Gindt ; Johannes P. M. Schelvis
• 刊名：Biochemistry
• 出版年：2007
• 出版时间：March 27, 2007
• 年：2007
• 卷：46
• 期：12
• 页码：3673 - 3681
• 全文大小：208K
• 年卷期：v.46,no.12(March 27, 2007)
• ISSN：1520-4995

文摘

Photolyases and cryptochromes are flavoproteins that belong to the class of blue-lightphotoreceptors. They usually bind two chromophores: flavin adenine dinucleotide (FAD), which formsthe active site, and a light-harvesting pigment, which is a 5,10-methenyltetrahydrofolate polyglutamate(MTHF) in most cases. In Escherichia coli photolyase (EcPhr), the MTHF cofactor is present insubstoichiometric amounts after purification, while in Vibrio cholerae cryptochrome-1 (VcCry1) the MTHFcofactor is bound more strongly and is present at stoichiometric levels after purification. In this paper, wehave used resonance Raman spectroscopy to monitor the effect of loss of MTHF on the protein-FADinteractions in EcPhr and to probe the protein-MTHF interactions in both EcPhr and VcCry1. We findthat removal of MTHF does not perturb protein-FAD interactions, suggesting that it may not affect thephysicochemical properties of FAD in EcPhr. Our data demonstrate that the pteridine ring of MTHF inEcPhr has different interactions with the protein matrix than that of MTHF in VcCry1. Comparison tosolution resonance Raman spectra of MTHF suggests that the carbonyl of its pteridine ring in EcPhrexperiences stronger hydrogen bonding and a more polar environment than in VcCry1, but that hydrogenbonding to the pteridine ring amine hydrogens is stronger in VcCry-1. These differences in hydrogenbonding may account for the higher binding affinity of MTHF in VcCry1 compared to EcPhr.