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Volume 10, Issue 8 (Suppl)

J Proteomics Bioinform, an open access journal

ISSN: 0974-276X

Structural Biology 2017

September 18-20, 2017

International Conference on

Structural Biology

September 18-20, 2017 Zurich, Switzerland

Christian Biertumpfel, J Proteomics Bioinform 2017, 10:8(Suppl)

DOI: 10.4172/0974-276X-C1-0100

Holliday junction resolvase GEN1 functions as a versatile DNA sensor and processor

Christian Biertumpfel

Max Planck Institute of Biochemistry, Germany

everal DNA repair and maintenance pathways depend on the correct and efficient processing of DNA intermediates by

structure-specific nucleases. Human Holliday junction resolvase GEN1 seems to be an enzyme of last resort for recognizing

and cleaving a specific range of DNA structures. The crystal structure of human GEN1 in complex with Holliday junction

DNA pinpointed to a crucial role of the chromodomain for efficient DNA recognition and cleavage. We further characterized

different DNA-binding modes of GEN1 using biochemical methods in combination with structure-guided mutagenesis.

The analysis highlights the importance of the arch region to distinguish between different DNA substrates. In addition, we

identified a cluster of positive amino acids shadowing the chromodomain to assist the enzyme for robust DNA recognition.

Moreover, we directly show that GEN1 operates as a monomer with 5’ flap DNA and as a dimer in complex with DNA four-

way junctions, which is a unique feature in the Rad2/XPG nuclease family. This linked cleavage mechanism ensures that DNA

junctions are resolved in a strictly symmetric manner without altering DNA information. GEN1’s DNA recognition features

make it a versatile tool for DNA processing and for maintaining genome integrity.

Biography

Christian Biertumpfel obtained his PhD degree from the European Molecular Biology Laboratory (EMBL) and the Ruprecht Karls University of Heidelberg, Germany.

His PhD research focused on the crystallization and characterization of Holliday junction resolvases. During his Postdoctoral time at the National Institute of

Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD, USA, he could solve a first crystal structure of a Holliday junction resolvase from T4 phages in

complex with a DNA four-way junction. Furthermore, together with Wei Yang he determined the structure and mechanism of human DNA polymerase η functioning

as a molecular splint. After a short period at the Vaccine Research Center, NIAID, NIH, he moved to the Max Planck Institute of Biochemistry, Martinsried, Germany

as a Max Planck Research Group Leader. Recently, the Biertumpfel Lab obtained structural information on the human Holliday junction resolvase GEN1 and they

found for the first time a chromodomain extending a nuclease domain.

biertuempfel@biochem.mpg.de

Figure1:

Holliday junction

resolvase GEN1 is a

monomer in solution and

thus, cleavage competent

for 5’ flap substrates.

However, it can only cleave

DNA four-way junctions by

forming an active nuclease

dimer.

Figure2:

Structure

of human Holliday

junction resolvase

GEN1 in complex

with a DNA four-way

junction. The nuclease

domain is extended

by a chromodomain

for efficient DNA

recognition and

cleavage.