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Stepwise activity of ClpY (HslU) mutants in the processive degradation of Escherichia coli ClpYQ (HslUV) protease substrates.

Abstract：

:In Escherichia coli, ClpYQ (HslUV) is a two-component ATP-dependent protease composed of ClpY (HslU), an ATPase with unfolding activity, and ClpQ (HslV), a peptidase. In the ClpYQ proteolytic complex, the hexameric rings of ClpY (HslU) are responsible for protein recognition, unfolding, and translocation into the proteolytic inner chamber of the dodecameric ClpQ (HslV). Each of the three domains, N, I, and C, in ClpY has its own distinct activity. The double loops (amino acids [aa] 137 to 150 and 175 to 209) in domain I of ClpY are necessary for initial recognition/tethering of natural substrates such as SulA, a cell division inhibitor protein. The highly conserved sequence GYVG (aa 90 to 93) pore I site, along with the GESSG pore II site (aa 265 to 269), contribute to the central pore of ClpY in domain N. These two central loops of ClpY are in the center of its hexameric ring in which the energy of ATP hydrolysis allows substrate translocation and then degradation by ClpQ. However, no data have been obtained to determine the effect of the central loops on substrate binding or as part of the processivity of the ClpYQ complex. Thus, we probed the features of ClpY important for substrate engagement and protease processivity via random PCR or site-specific mutagenesis. In yeast two-hybrid analysis and pulldown assays, using isolated ClpY mutants and the pore I or pore II site of ClpY, each was examined for its influence on the adjoining structural regions of the substrates. The pore I site is essential for the translocation of the engaged substrates. Our in vivo study of the ClpY mutants also revealed that an ATP-binding site in domain N, separate from its role in polypeptide (ClpY) oligomerization, is required for complex formation with ClpQ. Additionally, we found that the tyrosine residue at position 408 in ClpY is critical for stabilization of hexamer formation between subunits. Therefore, our studies suggest that stepwise activities of the ClpYQ protease are necessary to facilitate the processive degradation of its natural substrates.

journal_name

J Bacteriol

journal_title

Journal of bacteriology

authors

Hsieh FC,Chen CT,Weng YT,Peng SS,Chen YC,Huang LY,Hu HT,Wu YL,Lin NC,Wu WF

doi

10.1128/JB.05128-11

subject

Has Abstract

pub_date

2011-10-01 00:00:00

pages

5465-76

issue

eissn

0021-9193

issn

1098-5530

pii

JB.05128-11

journal_volume

193

pub_type

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Stepwise activity of ClpY (HslU) mutants in the processive degradation of Escherichia coli ClpYQ (HslUV) protease substrates.