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1g4b
From Proteopedia
CRYSTAL STRUCTURES OF THE HSLVU PEPTIDASE-ATPASE COMPLEX REVEAL AN ATP-DEPENDENT PROTEOLYSIS MECHANISM
Structural highlights
Function[HSLU_ECOLI] ATPase subunit of a proteasome-like degradation complex; this subunit has chaperone activity. The binding of ATP and its subsequent hydrolysis by HslU are essential for unfolding of protein substrates subsequently hydrolyzed by HslV. HslU recognizes the N-terminal part of its protein substrates and unfolds these before they are guided to HslV for hydrolysis.[1] [2] [3] [4] [5] [6] [7] [HSLV_ECOLI] Protease subunit of a proteasome-like degradation complex believed to be a general protein degrading machinery. The complex has been shown to be involved in the specific degradation of heat shock induced transcription factors such as RpoH and SulA. In addition, small hydrophobic peptides are also hydrolyzed by HslV. HslV has weak protease activity even in the absence of HslU, but this activity is induced more than 100-fold in the presence of HslU. HslU recognizes protein substrates and unfolds these before guiding them to HslV for hydrolysis. HslV is not believed to degrade folded proteins.[8] [9] [10] [11] [12] [13] [14] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedBACKGROUND: The bacterial heat shock locus HslU ATPase and HslV peptidase together form an ATP-dependent HslVU protease. Bacterial HslVU is a homolog of the eukaryotic 26S proteasome. Crystallographic studies of HslVU should provide an understanding of ATP-dependent protein unfolding, translocation, and proteolysis by this and other ATP-dependent proteases. RESULTS: We present a 3.0 A resolution crystal structure of HslVU with an HslU hexamer bound at one end of an HslV dodecamer. The structure shows that the central pores of the ATPase and peptidase are next to each other and aligned. The central pore of HslU consists of a GYVG motif, which is conserved among protease-associated ATPases. The binding of one HslU hexamer to one end of an HslV dodecamer in the 3.0 A resolution structure opens both HslV central pores and induces asymmetric changes in HslV. CONCLUSIONS: Analysis of nucleotide binding induced conformational changes in the current and previous HslU structures suggests a protein unfolding-coupled translocation mechanism. In this mechanism, unfolded polypeptides are threaded through the aligned pores of the ATPase and peptidase and translocated into the peptidase central chamber. Crystal structures of the HslVU peptidase-ATPase complex reveal an ATP-dependent proteolysis mechanism.,Wang J, Song JJ, Franklin MC, Kamtekar S, Im YJ, Rho SH, Seong IS, Lee CS, Chung CH, Eom SH Structure. 2001 Feb 7;9(2):177-84. PMID:11250202[15] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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