Secretion of Bacillus subtilis levansucrase. Fe(III) could act as a cofactor in an efficient coupling of the folding and translocation processes
- 15 January 1990
- journal article
- research article
- Published by Portland Press Ltd. in Biochemical Journal
- Vol. 265 (2) , 375-382
- https://doi.org/10.1042/bj2650375
Abstract
The refolding of levansucrase denatured by urea was studied as a possible model for the second step of the secretion pathway of this protein. The folding-unfolding transition was monitored by measuring intrinsic fluorescence and resistance to proteolysis. Both methods provided the same estimation for the unfolding free energy of levansucrase, delta GD, which was 30.1 +/- 1.7 kJ.mol-1 (7.2 +/- 0.4 kcal.mol-1) at pH 7 in 0.1 M-potassium phosphate buffer. The rate of refolding was greatly enhanced by Fe3+, whereas the Fe3+ chelator EDTA prevented correct refolding. Fe3+ allowed the protein to reach its folded form in medium in which the dielectric constant had been lowered by ethanol. The efficiency in vivo of the export of levansucrase bearing an amino acid modification which blocks the second step of the translocation pathway was greatly increased by high concentrations of Fe3+ in the culture medium. Assuming that the protein folding governs the second step of the secretion process of levansucrase, we discuss from an irreversible thermodynamic point of view the possible role of Fe3+ in the efficient coupling of the two events.This publication has 26 references indexed in Scilit:
- Secretion and membrane assemblyTrends in Biochemical Sciences, 1989
- Preprotein conformation: the year's major theme in translocation studiesTrends in Biochemical Sciences, 1988
- The ‘molten globule’ state is involved in the translocation of proteins across membranes?FEBS Letters, 1988
- Mutants of Bacillus subtilis Defective in Protein ExportMicrobiology, 1988
- Secretion Mechanism of Bacillus subtilis Levansucrase: Characterization of the Second StepMicrobiology, 1988
- Hyperproduction of Exocellular Levansucrase by Bacillus subtilis: Examination of the Phenotype of a sacUh StrainMicrobiology, 1984
- “Western Blotting”: Electrophoretic transfer of proteins from sodium dodecyl sulfate-polyacrylamide gels to unmodified nitrocellulose and radiographic detection with antibody and radioiodinated protein AAnalytical Biochemistry, 1981
- Levansucrase of Bacillus subtilisEuropean Journal of Biochemistry, 1980
- Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4Nature, 1970
- The Cross-linking of Proteins with Glutaraldehyde and its use for the preparation of immunoadsorbentsImmunochemistry, 1969