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The Membrane‐Bound Lon Protease from Thermoplasma Displays Unfolding Activity
Author(s) -
Besche Henrike,
Navon Amiel,
Zwickl Peter
Publication year - 2006
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1560/0env-nq8b-2wg6-nh8r
Subject(s) - chemistry , green fluorescent protein , calmodulin , protease , thermoplasma acidophilum , atp hydrolysis , biochemistry , biophysics , fusion protein , atpase , membrane , enzyme , recombinant dna , gene , biology
The membrane‐bound Lon protease from Thermoplasma acidophilum (Ta Lon) was shown to unfold and degrade a fusion of the green fluorescent protein with calmodulin (GFP—CaM). Unfolding and degradation were ATP‐dependent reactions and could be inhibited by calcium ions, which are known to stabilize calmodulin. Notably, an inverse fusion of the same proteins, i.e., CaM—GFP, as well as GFP or GFP‐SsrA, was neither unfolded nor degraded. Thus, Ta Lon seems to unfold and degrade preferentially protein substrates with an extended unstructured C‐terminus. A set of Ta Lon variants mutated in critical residues of the AAA + domain, were tested for their respective ATPase and GFP—CaM unfolding activity. This analysis revealed that the rate of ATP hydrolysis correlated with the efficiency of the GFP—CaM unfolding activity. In summary, we show here that the membrane‐bound Ta Lon protease displays an unfolding activity, which is correlated with the rate of ATP hydrolysis.