A Lon-like protease with no ATP-powered unfolding activity

Lon proteases are a family of ATP-dependent proteases involved in protein quality control, with a unique proteolytic domain and an AAA(+) (ATPases associated with various cellular activities) module accommodated within a single polypeptide chain. They were classified into two types as either the ubi...

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Veröffentlicht in:PloS one 2012-07, Vol.7 (7), p.e40226-e40226
Hauptverfasser: Liao, Jiahn-Haur, Kuo, Chiao-I, Huang, Ya-Yi, Lin, Yu-Ching, Lin, Yen-Chen, Yang, Chen-Yui, Wu, Wan-Ling, Chang, Wei-Hau, Liaw, Yen-Chywan, Lin, Li-Hua, Chang, Chung-I, Wu, Shih-Hsiung
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Sprache:eng
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Zusammenfassung:Lon proteases are a family of ATP-dependent proteases involved in protein quality control, with a unique proteolytic domain and an AAA(+) (ATPases associated with various cellular activities) module accommodated within a single polypeptide chain. They were classified into two types as either the ubiquitous soluble LonA or membrane-inserted archaeal LonB. In addition to the energy-dependent forms, a number of medically and ecologically important groups of bacteria encode a third type of Lon-like proteins in which the conserved proteolytic domain is fused to a large N-terminal fragment lacking canonical AAA(+) motifs. Here we showed that these Lon-like proteases formed a clade distinct from LonA and LonB. Characterization of one such Lon-like protease from Meiothermus taiwanensis indicated that it formed a hexameric assembly with a hollow chamber similar to LonA/B. The enzyme was devoid of ATPase activity but retained an ability to bind symmetrically six nucleotides per hexamer; accordingly, structure-based alignment suggested possible existence of a non-functional AAA-like domain. The enzyme degraded unstructured or unfolded protein and peptide substrates, but not well-folded proteins, in ATP-independent manner. These results highlight a new type of Lon proteases that may be involved in breakdown of excessive damage or unfolded proteins during stress conditions without consumption of energy.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0040226