Structural highlights
FunctionHSLV_STAAM Protease subunit of a proteasome-like degradation complex believed to be a general protein degrading machinery. Publication Abstract from PubMedHslUV is a bacterial heat shock protein complex consisting of the AAA+ ATPase component HslU and the protease component HslV. HslV is a threonine (Thr) protease employing the N-terminal Thr residue in the mature protein as the catalytic residue. To date, HslUV from Gram-negative bacteria has been extensively studied. However, the mechanisms of action and activation of HslUV from Gram-positive bacteria, which have an additional N-terminal sequence before the catalytic Thr residue, remain to be revealed. In this study, we determined the crystal structures of HslV from the Gram-positive bacterium Staphylococcus aureus with and without HslU in the crystallization conditions. The structural comparison suggested that a structural transition to the symmetric form of HslV was triggered by ATP-bound HslU. More importantly, the additional N-terminal sequence was cleaved in the presence of HslU and ATP, exposing the Thr9 residue at the N-terminus and activating the ATP-dependent protease activity. Further biochemical studies demonstrated that the exposed N-terminal Thr residue is critical for catalysis with binding to the symmetric HslU hexamer. Since eukaryotic proteasomes have a similar additional N-terminal sequence, our results will improve our understanding of the common molecular mechanisms for the activation of proteasomes. Cleavage-Dependent Activation of ATP-Dependent Protease HslUV from Staphylococcus aureus.,Jeong S, Ahn J, Kwon AR, Ha NC Mol Cells. 2020 Aug 31;43(8):694-704. doi: 10.14348/molcells.2020.0074. PMID:32694241[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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