Structural studies on the HsdR subunit of the EcoR124I endonuclease from E. coli

Mikalai Lapkouski 1, Santosh Panjikar 2, Ivana Kuta Smatanova 1

 and Eva Csefalvay 1


1Institute of Physical Biology, University of South Bohemia in Ceske Budejovice,

Zamek 136, CZ-373 33 Nove Hrady, Czech Republic

2EMBL Hamburg c/o DESY, Notkestraße 85, 22603 Hamburg, Germany


Many genetic processes require the action of large protein machines that act on DNA. We are currently concentrating on the Type I restriction enzymes which are complex molecular machines that protect bacteria by cutting invading viral DNA in an ATP-dependent manner [1]. The complex is composed of three distinct subunits responsible for site-specific DNA sequence recognition (HsdS), methylation (HsdM) and ATP-dependent DNA translocation and cleavage (HsdR).

We are interested in solving the structure of the 119 kDa HsdR subunit of the Type I restriction-modification enzyme EcoR124I (R.EcoR124I) from E. coli. Solving the structure will shed the light onto the enzymatic action and on the protein-DNA interface.

We have recently crystallized the motor subunit (HsdR) of the EcoR124I enzyme and preliminary crystallization studies were performed showing that crystals belong to the primitive monoclinic space group P2/P2(1) and the unit cell parameters being a = 86.0 Ǻ, b = 125.1 Ǻ, c = 128.8 Ǻ, β = 108.1°. Native data were collected to 2.45 Ǻ resolution at the X12 synchrotron beamline of the EMBL Hamburg.

1.   Louise K. Stanley and Mark D. Szczelkun. Direct and random routing of a molecular motor protein at a DNA junction. Nucleic Acids Res. 2006; 34(16):4387-94.



This research was supported by the Ministry of Education, Youth and Sports of the Czech Republic

(MSM6007665808, LC06010) and by the Academy of Sciences of the Czech Republic (Institutional

research concept AVOZ60870520).