title: The ssrA-Tag Facilitated Degradation of an Integral Membrane Protein.
abstract: ATP-dependent degradation plays a critical role in the quality control and recycling of proteins in cells. However, complete degradation of membrane proteins by ATP-dependent proteases in bacteria is not well-studied. We discovered that the degradation of a multidomain and multispan integral membrane protein AcrB could be facilitated by the introduction of a ssrA-tag at the C-terminus of the protein sequence and demonstrated that the cytoplasmic unfoldase-protease complex ClpXP was involved in the degradation. This is the first report to our knowledge to reveal that the ClpXP complex is capable of degrading integral membrane proteins. The chaperone SspB also played a role in the degradation. Using purified proteins, we demonstrated that the addition of the ssrA-tag did not drastically affect the structure of AcrB, and the degradation of detergent solubilized AcrB by purified ClpXP could be observed in vitro.
authors.affiliation: Department of Chemistry and ‡Department of Molecular and Cellular Biochemistry, University of Kentucky , Lexington, Kentucky 40506, United States.
authors.forename: Qian
authors.initials: Q
authors.lastname: Chai
authors.affiliation: Department of Chemistry and ‡Department of Molecular and Cellular Biochemistry, University of Kentucky , Lexington, Kentucky 40506, United States.
authors.forename: Zhaoshuai
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Chemistry and ‡Department of Molecular and Cellular Biochemistry, University of Kentucky , Lexington, Kentucky 40506, United States.
authors.forename: Stacy R
authors.initials: SR
authors.lastname: Webb
authors.affiliation: Department of Chemistry and ‡Department of Molecular and Cellular Biochemistry, University of Kentucky , Lexington, Kentucky 40506, United States.
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Dutch
authors.affiliation: Department of Chemistry and ‡Department of Molecular and Cellular Biochemistry, University of Kentucky , Lexington, Kentucky 40506, United States.
authors.forename: Yinan
authors.initials: Y
authors.lastname: Wei
mesh_terms: D000595:Amino Acid Sequence; D049071:Endopeptidase Clp / Q000378:metabolism*; D004926:Escherichia coli / Q000737:chemistry / Q000378:metabolism*; D004927:Escherichia coli Infections / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation; D059748:Proteolysis
chemical_list: D049071:Endopeptidase Clp; D029968:Escherichia coli Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C083496:AcrB protein, E coli; C483573:ClpXP protease, E coli