High-affinity binding of Escherichia coli SecB to the signal sequence region of a presecretory protein - PubMed (original) (raw)
Comparative Study
High-affinity binding of Escherichia coli SecB to the signal sequence region of a presecretory protein
M Watanabe et al. Proc Natl Acad Sci U S A. 1995.
Abstract
The Escherichia coli cytosolic homotetrameric protein SecB is known to be involved in protein export across the plasma membrane. A currently prevalent view holds that SecB functions exclusively as a chaperone interacting nonspecifically with unfolded proteins, not necessarily exported proteins, whereas a contrary view holds that SecB functions primarily as a specific signal-recognition factor--i.e., in binding to the signal sequence region of exported proteins. To experimentally resolve these differences we assayed for binding between chemically pure SecB and chemically pure precursor (p) form (containing a signal sequence) and mature (m) form (lacking a signal sequence) of a model secretory protein (maltose binding protein, MBP) that was C-terminally truncated. Because of the C-terminal truncation, neither p nor m was able to fold. We found that SecB bound with 100-fold higher affinity to p (Kd 0.8 nM) than it bound to m (Kd 80 nM). As the presence of the signal sequence in p is the only feature that distinguished p from m, these data strongly suggest that the high-affinity binding of SecB is to the signal sequence region and not the mature region of p. Consistent with this conclusion, we found that a wild-type signal peptide, but not an export-incompetent mutant signal peptide of another exported protein (LamB), competed for binding to p. Moreover, the high-affinity binding of SecB to p was resistant to 1 M salt, whereas the low-affinity binding of SecB to m was not. These qualitative differences suggested that SecB binding to m was primarily by electrostatic interactions, whereas SecB binding to p was primarily via hydrophobic interactions, presumably with the hydrophobic core of the signal sequence. Taken together our data strongly support the notion that SecB is primarily a specific signal-recognition factor.
Similar articles
- SecB-independent export of Escherichia coli ribose-binding protein (RBP): some comparisons with export of maltose-binding protein (MBP) and studies with RBP-MBP hybrid proteins.
Collier DN, Strobel SM, Bassford PJ Jr. Collier DN, et al. J Bacteriol. 1990 Dec;172(12):6875-84. doi: 10.1128/jb.172.12.6875-6884.1990. J Bacteriol. 1990. PMID: 2254262 Free PMC article. - Regions of maltose-binding protein that influence SecB-dependent and SecA-dependent export in Escherichia coli.
Strobel SM, Cannon JG, Bassford PJ Jr. Strobel SM, et al. J Bacteriol. 1993 Nov;175(21):6988-95. doi: 10.1128/jb.175.21.6988-6995.1993. J Bacteriol. 1993. PMID: 8226642 Free PMC article. - Export of the periplasmic maltose-binding protein of Escherichia coli.
Bassford PJ Jr. Bassford PJ Jr. J Bioenerg Biomembr. 1990 Jun;22(3):401-39. doi: 10.1007/BF00763175. J Bioenerg Biomembr. 1990. PMID: 2202725 Review. - SecB, one small chaperone in the complex milieu of the cell.
Randall LL, Hardy SJ. Randall LL, et al. Cell Mol Life Sci. 2002 Oct;59(10):1617-23. doi: 10.1007/pl00012488. Cell Mol Life Sci. 2002. PMID: 12475171 Free PMC article. Review.
Cited by
- Cotranslational folding of alkaline phosphatase in the periplasm of Escherichia coli.
Elfageih R, Karyolaimos A, Kemp G, de Gier JW, von Heijne G, Kudva R. Elfageih R, et al. Protein Sci. 2020 Oct;29(10):2028-2037. doi: 10.1002/pro.3927. Epub 2020 Aug 24. Protein Sci. 2020. PMID: 32790204 Free PMC article. - Protein folding while chaperone bound is dependent on weak interactions.
Wu K, Stull F, Lee C, Bardwell JCA. Wu K, et al. Nat Commun. 2019 Oct 23;10(1):4833. doi: 10.1038/s41467-019-12774-6. Nat Commun. 2019. PMID: 31645566 Free PMC article. - The Sec System: Protein Export in Escherichia coli.
Crane JM, Randall LL. Crane JM, et al. EcoSal Plus. 2017 Nov;7(2):10.1128/ecosalplus.ESP-0002-2017. doi: 10.1128/ecosalplus.ESP-0002-2017. EcoSal Plus. 2017. PMID: 29165233 Free PMC article. Review. - Protein export through the bacterial Sec pathway.
Tsirigotaki A, De Geyter J, Šoštaric N, Economou A, Karamanou S. Tsirigotaki A, et al. Nat Rev Microbiol. 2017 Jan;15(1):21-36. doi: 10.1038/nrmicro.2016.161. Epub 2016 Nov 28. Nat Rev Microbiol. 2017. PMID: 27890920 Review. - Identification of protein secretion systems and novel secreted proteins in Rhizobium leguminosarum bv. viciae.
Krehenbrink M, Downie JA. Krehenbrink M, et al. BMC Genomics. 2008 Jan 29;9:55. doi: 10.1186/1471-2164-9-55. BMC Genomics. 2008. PMID: 18230162 Free PMC article.
References
- Gene. 1989 Jan 30;75(1):167-75 - PubMed
- Proc Natl Acad Sci U S A. 1989 Apr;86(8):2728-32 - PubMed
- Nature. 1993 Nov 25;366(6453):351-4 - PubMed
- Cell. 1989 Aug 25;58(4):695-705 - PubMed
- J Biol Chem. 1989 Oct 15;264(29):17293-7 - PubMed
Publication types
MeSH terms
Substances
LinkOut - more resources
Full Text Sources
Research Materials
Miscellaneous