XXII. BIOCHEMICKÝ ZJAZD - Jesseniova lekárska fakulta

Posters
71.
HEXaMEr formaTION trIGGErs a SWITCH frOM an INaCTIve TO an
aCTIve CONformaTION IN HUMan MITOCHONDrial LON prOTEaSE
Vladimír Pevala 1 , Jacob A. Bauer 1 , Javier García-Nafría 2 , Gabriela Ondrovičová 1 ,
Ľuboš Ambro 1 , Elena Blagova 2 , Vladimir M. Levdikov 2 , Anthony J. Wilkinson 2 ,
Keith S.Wilson 2 and Eva Kutejová 1
1
Institute of Molecular Biology, Department of Biochemistry, SAS, Dúbravská cesta 21,
845 51 Bratislava, Slovakia,
2
Structural Biology Laboratory, Department of Chemistry, University of York,
York YO10 5YW, UK
Although Lon is one of the least complicated ATP-dependent proteases, a structure
of the full-length protein still has not been determined. At present, structures have
been solved of a fragment of the N-terminus, the small α-domain and the proteolytic
domain. We determined the crystal structure of the proteolytic domain of the human
mitochondrial Lon protease. Although the overall structure is very similar to the EcLon
one, the conformation around the active site more closely resembled that seen in the
Methanococcus jannaschii Lon structure. A detailed analysis of these three structures led
us to propose a mechanism by which hexamer formation is coupled to a conformational
transition at the active site, which converts the inactive conformation seen in the hLon
structure to one resembling that seen in the EcLon one. To better understand the roles
of the proteolytic domain in the overall functions of human Lon protease, we designed
several point mutations in this domain based on the known Lon protease crystal structures.
We then tested their influence on protease, peptidase, and ATPase activity as well
as on oligomer formation and stability.
Acknowledgement: This work was supported by VEGA 2/0141/08, APVV-0024-07 and
by European Commission funding SPINE2–COMPLEXES project LSHG–CT–2006–031220.
We thank the staff at the ESRF (beamline ID14-4) for provision of synchrotron facilities,
and Johan Turkenberg and Sam Hart for assistance with data collection.
194 XXII. Biochemistry Congress, Martin