PMID:16076848

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Citation

Sakoh, M, Ito, K and Akiyama, Y (2005) Proteolytic activity of HtpX, a membrane-bound and stress-controlled protease from Escherichia coli. J. Biol. Chem. 280:33305-10

Abstract

Escherichia coli HtpX is a putative membrane-bound zinc metalloprotease that has been suggested to participate in the proteolytic quality control of membrane proteins in conjunction with FtsH, a membrane-bound and ATP-dependent protease. Here, we biochemically characterized HtpX and confirmed its proteolytic activities against membrane and soluble proteins. HtpX underwent self-degradation upon cell disruption or membrane solubilization. Consequently, we purified HtpX under denaturing conditions and then refolded it in the presence of a zinc chelator. When supplemented with Zn2+, the purified enzyme exhibited self-cleavage activity. In the presence of zinc, it also degraded casein and cleaved a solubilized membrane protein, SecY. We verified its ability to cleave SecY in vivo by overproducing both HtpX and SecY. These results showed that HtpX is a zinc-dependent endoprotease member of the membrane-localized proteolytic system in E. coli.

Links

PubMed Online version:10.1074/jbc.M506180200

Keywords

Adenosine Triphosphate/metabolism; Bacterial Proteins/metabolism; Caseins/metabolism; Chelating Agents/pharmacology; Endopeptidases/metabolism; Escherichia coli/enzymology; Escherichia coli/growth & development; Escherichia coli Proteins/isolation & purification; Escherichia coli Proteins/metabolism; Heat-Shock Proteins/isolation & purification; Heat-Shock Proteins/metabolism; Immunoblotting; Membrane Proteins/metabolism; Precipitin Tests; Protein Denaturation; Protein Renaturation/drug effects; Zinc/metabolism; Zinc/pharmacology

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