Zinc stabilizes the SecB binding site of SecA

SecB has a significant function in Escherichia coli cytoplasmic membrane preprotein translocation. A study on the molecular chaperone SecB and SecA-SecB interaction at the membrane demonstrates that the SecB binding site of SecA contains a zinc atom that is coordinated by Cys residues. Since zinc is required for the functional binding of SecB to SecA, it is believed that SecA is a metalloprotein. Experimental methodology, findings and conclusions are discussed.