Document Detail

Detection of Distinct α-Helical Rearrangements of CPD Photolyase upon Substrate Binding by FTIR Spectroscopy.
MedLine Citation:
PMID:  23331252     Owner:  NLM     Status:  Publisher    
Photolyases (PHRs) utilize near UV/blue light to specifically repair the major photoproducts (PPs) of UV-induced damaged DNA by utilizing near UV/blue light. The cyclobutane pyrimidine dimer (CPD)-PHR from Escherichia coli binds flavin adenine dinucleotide (FAD) as a cofactor and 5,10-methenyltetrahydrofolate (MTHF) as a light harvesting pigment, and specifically repairs CPD lesions. By comparison, a second photolyase known as (6-4) PHR present in a range of higher organisms uniquely repairs (6-4)PPs. To understand the repair mechanism and the substrate specificity that distinguish CPD-PHR from (6-4) PHR, we applied Fourier transform infrared (FTIR) spectroscopy to bacterial CPD-PHR in the presence or absence of a well-defined DNA substrate, while we have studied on vertebrate (6-4) PHR. PHRs show light-induce reduction of FAD, and photorepair by CPD-PHR involves electron transfer from the photoexcited FADH- to the damaged DNA for cleaving the dimers to maintain the DNA's integrity. Here, we measured difference FTIR spectra for the photoactivation and DNA photorepair processes of CPD-PHR. We identified light-dependent signals only in the presence of substrate. The signals, presumably arising from a protonated carboxylic acid or the DNA substrate, implicate the occurrence of potential protein and substrate dynamics of the repair process. Deuterium exchange FTIR measurements of CPD-PHR highlights the potential differences in the photoactivation and photorepair mechanism in comparison to (6-4) PHR. While CPD and (6-4) PHRs appear to exhibit similar overall structures, our studies indicate that the conformational changes, especially α-helices perturbations, initiated within these enzymes upon binding their respective DNA substrates are quite diverse.
I M Mahaputra Wijaya; Yu Zhang; Tatsuya Iwata; Junpei Yamamoto; Kenichi Hitomi; Shigenori Iwai; Elizabeth Dickinson Getzoff; Hideki Kandori
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-21
Journal Detail:
Title:  Biochemistry     Volume:  -     ISSN:  1520-4995     ISO Abbreviation:  Biochemistry     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-1-21     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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