Endogenous
substrates-recognition and degradation by the yeast Lon protease.
Katarina Slezakova (1), Gabriela Durcova (1), Dusan Perecko (1), Natalia
Parkhomenko (2), Jiri Janata (2), Eva Kutejova (1)
(1) Department of Enzymology, Institute of Molecular Biology, Dubravska cesta
21, Bratislava, 845 51, Slovak Republic (slezakova@hotmail.com); (2) Institute
of Microbiology, Czech Academy of Sciences, Videnska 1083, 142 20 Praha 4,
Czech Republic
Lon protease
plays an crucial role in maintenace of fully-functional mitochondria. Its
substrates are missfolded and missasembled proteins. Agregated ones loose the
chance to be the substrate of the Lon protease as we have shown by the
experiment with the heat denaturated MPPalfa. Native MPPalfa is a good
endogenous substrate of the Lon. Addition of the beta subunit of MPP leads to
formation of the functional complex of MPP. Subsequently alpha subunit of MPP
binded in this complex is protected against degradation. The alpha subunits
remain not integrated into the complex are still objects for the Lon protease.
We have proved the formation of the complex between the Lon and alpha subunit
of the MPP using cosslinking and SDS PAGE. Complex formation stimulates ATPase
activity of the Lon protease. The same results were obtained for the C-terminal
deletion mutants (-2 aa and -17 aa) that are able to form the functional
complex with the beta subunit of MPP. No ATP-ase activity stimulation and no
cleavage were observed when -17 aa mutant have lost the conformational
stability during storage in refrigerator. Human Lon protease can substitute the
yeast Lon protease in the process of alfa subunit cleavage.