Prof. RNDr. Rudiger Ettrich, C4SYS-Center for Systems Biology, Institute of Microbiology, Academy of Sciences of the Czech Republic
Tuesday 20th October, 1.00 p.m., Keynes Lecture Theatre 6
Type I restriction-modification enzymes differ significantly from the type II enzymes commonly used as molecular biology reagents. On hemi-methylated DNAs type I enzymes act as conventional adenine methylases at specific target sequences, but unmethylated targets induce them to pull thousands of basepairs through the stationary enzyme before it cleaves distant sites nonspecifically. Biochemical, biophysical, and molecular biological studies of their translocation and cleavage mechanisms offer a wealth of detail that has lacked a structural framework. The crystal structure, resolved at 2.6 Å, of the motor subunit responsible for DNA translocation and cleavage by the type I enzyme EcoR124I shows a planar array of four domains, and ATP-mediated contact between endonuclease and helicase domains that may couple cleavage and translocase activities (1). Crystallography, point-mutations, and in vivo and in vitro assays in combination with computational modeling reveal how interdomain engagement brings DNA cleavage under the control of translocation (2,3), and provide new general insights into type I restriction-modification complexes.
The proposed transport and regulatory mechanism provide new insights into the molecular basis of several human diseases caused by dysfunctional mitochondrial carriers.
- Mikalai Lapkouski, Santosh Panjikar, Pavel Janscak, Ivana Kuta Smatanova, Jannette Carey, Rüdiger Ettrich, Eva Csefalvay (2009) Structure of the motor subunit of type I restriction-modification complex EcoR124I. Nat Struct Mol Biol 16: 1. 94-95.
- Eva Csefalvay, Mikalai Lapkouski, Alena Guzanova, Ladislav Csefalvay, Tatjana Baikova, Igor Shevelev, Vitali Bialevich, Katsiaryna Shamayeva, Pavel Janscak, Ivana Kuta Smatanova, Santosh Panjikar, Jannette Carey, Marie Weiserova, Rüdiger Ettrich (2015) Functional coupling of duplex translocation to DNA cleavage in a type I restriction enzyme, PLoS ONE 10 (6): e0128700.
- D Sinha, K Shamayeva, V Ramasubramani, D Reha, V Bialevich, M Khabiri, N Milbar, A Guzanova, M Weiserova, E Csefalvay, J Carey, R Ettrich(2014) Interdomain communication in the endonuclease/motor subunit of Type I restriction-modification enzyme EcoR124I Journal of Molecular Modeling 20 (7): 2334.