TY  - JOUR
A1  - Bangalore, Disha M.
A1  - Heil, Hannah S.
A1  - Mehringer, Christian F.
A1  - Hirsch, Lisa
A1  - Hemmen, Katharina
A1  - Heinze, Katrin G.
A1  - Tessmer, Ingrid
T1  - Automated AFM analysis of DNA bending reveals initial lesion sensing strategies of DNA glycosylases
JF  - Scientific Reports
N2  - Base excision repair is the dominant DNA repair pathway of chemical modifications such as deamination, oxidation, or alkylation of DNA bases, which endanger genome integrity due to their high mutagenic potential. Detection and excision of these base lesions is achieved by DNA glycosylases. To investigate the remarkably high efficiency in target site search and recognition by these enzymes, we applied single molecule atomic force microscopy (AFM) imaging to a range of glycosylases with structurally different target lesions. Using a novel, automated, unbiased, high-throughput analysis approach, we were able to resolve subtly different conformational states of these glycosylases during DNA lesion search. Our results lend support to a model of enhanced lesion search efficiency through initial lesion detection based on altered mechanical properties at lesions. Furthermore, its enhanced sensitivity and easy applicability also to other systems recommend our novel analysis tool for investigations of diverse, fundamental biological interactions.
KW  - atomic-force microscopy
KW  - base pairs
KW  - molecular structure
KW  - crystal structure
KW  - structural basis
KW  - repair
KW  - recognition
KW  - 8-oxoguanine
KW  - thymine
KW  - mismatches
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-231338
VL  - 10
ER  - 
TY  - JOUR
A1  - Buechner, Claudia N.
A1  - Maiti, Atanu
A1  - Drohat, Alexander C.
A1  - Tessmer, Ingrid
T1  - Lesion search and recognition by thymine DNA glycosylase revealed by single molecule imaging
JF  - Nucleic Acids Research
N2  - The ability of DNA glycosylases to rapidly and efficiently detect lesions among a vast excess of nondamaged DNA bases is vitally important in base excision repair (BER). Here, we use singlemolecule imaging by atomic force microscopy (AFM) supported by a 2-aminopurine fluorescence base flipping assay to study damage search by human thymine DNA glycosylase (hTDG), which initiates BER of mutagenic and cytotoxic G:T and G:U mispairs in DNA. Our data reveal an equilibrium between two conformational states of hTDG-DNA complexes, assigned as search complex (SC) and interrogation complex (IC), both at target lesions and undamaged DNA sites. Notably, for both hTDG and a second glycosylase, hOGG1, which recognizes structurally different 8-oxoguanine lesions, the conformation of the DNA in the SC mirrors innate structural properties of their respective target sites. In the IC, the DNA is sharply bent, as seen in crystal structures of hTDG lesion recognition complexes, which likely supports the base flipping required for lesion identification. Our results support a potentially general concept of sculpting of glycosylases to their targets, allowing them to exploit the energetic cost of DNA bending for initial lesion sensing, coupled with continuous (extrahelical) base interrogation during lesion search by DNA glycosylases.
KW  - Escherichia coli AlkA
KW  - undamaged DNA
KW  - substrate recognition
KW  - intrahelical lesion
KW  - uracil binding
KW  - structural basis
KW  - mismatch recognition
KW  - damaged DNA
KW  - base excision repair
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148795
VL  - 43
IS  - 5
ER  -