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Updated: Aug 4, 2026
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Biochemical and Structural Characterization of the Carbohydrate Transport Substrate-binding-protein SP0092
Published on: October 2, 2017
Zinc stabilizes the SecB binding site of SecA
P Fekkes1, J G de Wit, A Boorsma
1Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Goningen, The Netherlands.
Biochemistry
|April 23, 1999
Summary
Zinc ions stabilize the SecB binding domain of SecA, a key protein in bacterial protein transport. This stabilization is crucial for the functional interaction between SecB and SecA, ensuring efficient preprotein translocation.
Area of Science:
- Molecular Biology
- Protein Transport
- Biochemistry
Background:
- SecB is a molecular chaperone that directs preproteins to SecA at the cytoplasmic membrane in Escherichia coli.
- SecA recognizes SecB through its conserved carboxyl-terminal domain, which contains residues potentially involved in metal ion coordination.
Purpose of the Study:
- To investigate the role of metal ions in the interaction between SecB and SecA.
- To elucidate the mechanism by which SecB binds to SecA for preprotein translocation.
Main Methods:
- Treatment of SecA with zinc chelators and subsequent addition of ZnCl2.
- Assessing the effect of chelators and divalent cations (Cu2+, Zn2+) on SecB-SecA interaction.
- Atomic absorption and electrospray mass spectrometry to quantify zinc content in SecA.
Main Results:
- Zinc chelation abolished the stimulatory effect of SecB on SecA translocation ATPase activity.
- The interaction between SecB and the SecA binding domain was disrupted by chelators but restored by Zn2+ or Cu2+.
- SecA's carboxyl terminus contains one zinc atom per monomer.
Conclusions:
- A zinc ion stabilizes the SecB binding domain of SecA.
- Zinc binding promotes the functional interaction of SecB with SecA, facilitating preprotein translocation.
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