Removal of disulfide from acid stress chaperone HdeA does not wholly eliminate structure or function at low pH.

Autor:	Aguirre-Cardenas MI; Department of Chemistry and Biochemistry, California State University Northridge, 18111 Nordhoff St., Northridge, CA, 91330-8262, USA.; Present address: Department of Chemistry, University of California Riverside, 900 University Ave, Riverside, CA, 92521, USA., Geddes-Buehre DH; Department of Chemistry and Biochemistry, California State University Northridge, 18111 Nordhoff St., Northridge, CA, 91330-8262, USA., Crowhurst KA; Department of Chemistry and Biochemistry, California State University Northridge, 18111 Nordhoff St., Northridge, CA, 91330-8262, USA.
Jazyk:	angličtina
Zdroj:	Biochemistry and biophysics reports [Biochem Biophys Rep] 2021 Jul 01; Vol. 27, pp. 101064. Date of Electronic Publication: 2021 Jul 01 (Print Publication: 2021).
DOI:	10.1016/j.bbrep.2021.101064
Abstrakt:	HdeA is an acid-stress chaperone that operates in the periplasm of various strains of pathogenic gram-negative bacteria. Its primary function is to prevent irreversible aggregation of other periplasmic proteins when the bacteria enter the acidic environment of the stomach after contaminated food is ingested; its role is therefore to help the bacteria survive long enough to enter and colonize the intestines. The mechanism of operation of HdeA is unusual in that this helical homodimer is inactive when folded at neutral pH but becomes activated at low pH after the dimer dissociates and partially unfolds. Studies with chemical reducing agents previously suggested that the intramolecular disulfide bond is important for maintaining residual structure in HdeA at low pH and may be responsible for positioning exposed hydrophobic residues together for the purpose of binding unfolded client proteins. In order to explore its role in HdeA structure and chaperone function we performed a conservative cysteine to serine mutation of the disulfide. We found that, although residual structure is greatly diminished at pH 2 without the disulfide, it is not completely lost; conversely, the mutant is almost completely random coil at pH 6. Aggregation assays showed that mutated HdeA, although less successful as a chaperone than wild type, still maintains a surprising level of function. These studies highlight that we still have much to learn about the factors that stabilize residual structure at low pH and the role of disulfide bonds. (© 2021 The Authors. Published by Elsevier B.V.)
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu