Evidence that SecB enhances the activity of SecA

J. Kim, A. Miller, L. Wang, J. P. Müller, D. A. Kendall

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

In Escherichia coli, SecA is a critical component of the protein transport machinery which powers the translocation process by hydrolyzing ATP and recognizing signal peptides which are the earmark of secretory proteins. In contrast, SecB is utilized by only a subset of preproteins to prevent their premature folding and chaperone them to membrane-bound SecA. Using purified components and synthetic signal peptides, we have studied the interaction of SecB with SecA and with SecA-signal peptide complexes in vitro. Using a chemical cross-linking approach, we find that the formation of SecA-SecB complexes is accompanied by a decrease in the level of cross-linking of SecA dimers, suggesting that SecB induces a conformational change in SecA. Furthermore, functional signal peptides, but not dysfunctional ones, promote the formation of SecA-SecB complexes. SecB is also shown to directly enhance the ATPase activity of SecA in a concentration-dependent and saturable manner. To determine the biological consequence of this finding, the influence of SecB on the signal peptide-stimulated SecA/lipid ATPase was studied using synthetic peptides of varying hydrophobicity. Interestingly, the presence of SecB can sufficiently boost the response of signal peptides with moderate hydrophobicity such that it is comparable to the activity generated by a more hydrophobic peptide in the absence of SecB. The results suggest that SecB directly enhances the activity of SecA and provide a biochemical basis for the enhanced transport efficiency of preproteins in the presence of SecB in vivo.

Original languageEnglish (US)
Pages (from-to)3674-3680
Number of pages7
JournalBiochemistry
Volume40
Issue number12
DOIs
StatePublished - Mar 27 2001

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Protein Sorting Signals
Hydrophobicity
Hydrophobic and Hydrophilic Interactions
Adenosine Triphosphatases
Peptides
Protein Transport
Dimers
Escherichia coli
Machinery
Proteins
Adenosine Triphosphate
Membranes
Lipids

ASJC Scopus subject areas

  • Biochemistry

Cite this

Kim, J., Miller, A., Wang, L., Müller, J. P., & Kendall, D. A. (2001). Evidence that SecB enhances the activity of SecA. Biochemistry, 40(12), 3674-3680. https://doi.org/10.1021/bi002617z

Evidence that SecB enhances the activity of SecA. / Kim, J.; Miller, A.; Wang, L.; Müller, J. P.; Kendall, D. A.

In: Biochemistry, Vol. 40, No. 12, 27.03.2001, p. 3674-3680.

Research output: Contribution to journalArticle

Kim, J, Miller, A, Wang, L, Müller, JP & Kendall, DA 2001, 'Evidence that SecB enhances the activity of SecA', Biochemistry, vol. 40, no. 12, pp. 3674-3680. https://doi.org/10.1021/bi002617z
Kim J, Miller A, Wang L, Müller JP, Kendall DA. Evidence that SecB enhances the activity of SecA. Biochemistry. 2001 Mar 27;40(12):3674-3680. https://doi.org/10.1021/bi002617z
Kim, J. ; Miller, A. ; Wang, L. ; Müller, J. P. ; Kendall, D. A. / Evidence that SecB enhances the activity of SecA. In: Biochemistry. 2001 ; Vol. 40, No. 12. pp. 3674-3680.
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