Abstract
Mutant Escherichia coli strains in which export of the LamB protein (coded for by the lamB gene) to the outer membrane of the cell is prevented have been described previously. One of these mutant strains contains a small (12-base pair) deletion mutation within the region of the lamB gene that codes for the NH2-terminal signal sequence. In this mutant strain, export but not synthesis of the LamB protein is blocked. We have isolated pseudorevertants that restore export of functional LamB protein to the outer membrane. DNA sequence analysis showed that two of the revertants contain a point mutation in addition to the original deletion. These point mutations lead to amino acid substitutions within the signal sequence. Our results indicate that these secondary mutations efficiently suppress the export defect caused by the deletion mutation. Analysis of the secondary structure of the wild-type, mutant, and pseudorevertant LamB signal sequences suggests that the secondary mutations restore export by allowing the formation of a stable alpha-helical conformation in the central, hydrophobic region of the signal sequence.
Full text
PDFImages in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Austen B. M. Predicted secondary structures of amino-terminal extension sequences of secreted proteins. FEBS Lett. 1979 Jul 15;103(2):308–313. doi: 10.1016/0014-5793(79)81351-4. [DOI] [PubMed] [Google Scholar]
- Bachmann B. J., Low K. B., Taylor A. L. Recalibrated linkage map of Escherichia coli K-12. Bacteriol Rev. 1976 Mar;40(1):116–167. doi: 10.1128/br.40.1.116-167.1976. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bedouelle H., Bassford P. J., Jr, Fowler A. V., Zabin I., Beckwith J., Hofnung M. Mutations which alter the function of the signal sequence of the maltose binding protein of Escherichia coli. Nature. 1980 May 8;285(5760):78–81. doi: 10.1038/285078a0. [DOI] [PubMed] [Google Scholar]
- Bedouelle H., Hofnung M. Functional implications of secondary structure analysis of wild type and mutant bacterial signal peptides. Prog Clin Biol Res. 1981;63:399–403. [PubMed] [Google Scholar]
- Blobel G., Dobberstein B. Transfer of proteins across membranes. I. Presence of proteolytically processed and unprocessed nascent immunoglobulin light chains on membrane-bound ribosomes of murine myeloma. J Cell Biol. 1975 Dec;67(3):835–851. doi: 10.1083/jcb.67.3.835. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Chou P. Y., Fasman G. D. Empirical predictions of protein conformation. Annu Rev Biochem. 1978;47:251–276. doi: 10.1146/annurev.bi.47.070178.001343. [DOI] [PubMed] [Google Scholar]
- Chou P. Y., Fasman G. D. Prediction of the secondary structure of proteins from their amino acid sequence. Adv Enzymol Relat Areas Mol Biol. 1978;47:45–148. doi: 10.1002/9780470122921.ch2. [DOI] [PubMed] [Google Scholar]
- Cohn D. V., Smardo F. L., Jr, Morrissey J. J. Evidence for internal homology in bovine preproparathyroid hormone. Proc Natl Acad Sci U S A. 1979 Mar;76(3):1469–1471. doi: 10.1073/pnas.76.3.1469. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Coulondre C., Miller J. H. Genetic studies of the lac repressor. IV. Mutagenic specificity in the lacI gene of Escherichia coli. J Mol Biol. 1977 Dec 15;117(3):577–606. doi: 10.1016/0022-2836(77)90059-6. [DOI] [PubMed] [Google Scholar]
- Emr S. D., Bassford P. J., Jr Localization and processing of outer membrane and periplasmic proteins in Escherichia coli strains harboring export-specific suppressor mutations. J Biol Chem. 1982 May 25;257(10):5852–5860. [PubMed] [Google Scholar]
- Emr S. D., Hall M. N., Silhavy T. J. A mechanism of protein localization: the signal hypothesis and bacteria. J Cell Biol. 1980 Sep;86(3):701–711. doi: 10.1083/jcb.86.3.701. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Emr S. D., Hanley-Way S., Silhavy T. J. Suppressor mutations that restore export of a protein with a defective signal sequence. Cell. 1981 Jan;23(1):79–88. doi: 10.1016/0092-8674(81)90272-5. [DOI] [PubMed] [Google Scholar]
- Emr S. D., Hedgpeth J., Clément J. M., Silhavy T. J., Hofnung M. Sequence analysis of mutations that prevent export of lambda receptor, an Escherichia coli outer membrane protein. Nature. 1980 May 8;285(5760):82–85. doi: 10.1038/285082a0. [DOI] [PubMed] [Google Scholar]
- Emr S. D., Schwartz M., Silhavy T. J. Mutations altering the cellular localization of the phage lambda receptor, an Escherichia coli outer membrane protein. Proc Natl Acad Sci U S A. 1978 Dec;75(12):5802–5806. doi: 10.1073/pnas.75.12.5802. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Emr S. D., Silhavy T. J. Mutations affecting localization of an Escherichia coli outer membrane protein, the bacteriophage lambda receptor. J Mol Biol. 1980 Jul 25;141(1):63–90. doi: 10.1016/s0022-2836(80)80029-5. [DOI] [PubMed] [Google Scholar]
- Hedgpeth J., Clement J. M., Marchal C., Perrin D., Hofnung M. DNA sequence encoding the NH2-terminal peptide involved in transport of lambda receptor, an Escherichia coli secretory protein. Proc Natl Acad Sci U S A. 1980 May;77(5):2621–2625. doi: 10.1073/pnas.77.5.2621. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Laemmli U. K. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. doi: 10.1038/227680a0. [DOI] [PubMed] [Google Scholar]
- Marchal C., Perrin D., Hedgpeth J., Hofnung M. Synthesis and maturation of lambda receptor in Escherichia coli K-12: in vivo and in vitro expression of gene lamB under lac promoter control. Proc Natl Acad Sci U S A. 1980 Mar;77(3):1491–1495. doi: 10.1073/pnas.77.3.1491. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Raibaud O., Clément J. M., Hofnung M. Structure of the malB region in Escherichia coli K12. III. Correlation of the genetic map with the restriction map. Mol Gen Genet. 1979 Jul 24;174(3):261–267. doi: 10.1007/BF00267798. [DOI] [PubMed] [Google Scholar]
- Randall-Hazelbauer L., Schwartz M. Isolation of the bacteriophage lambda receptor from Escherichia coli. J Bacteriol. 1973 Dec;116(3):1436–1446. doi: 10.1128/jb.116.3.1436-1446.1973. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Randall L. L., Hardy S. J., Josefsson L. G. Precursors of three exported proteins in Escherichia coli. Proc Natl Acad Sci U S A. 1978 Mar;75(3):1209–1212. doi: 10.1073/pnas.75.3.1209. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rosenblatt M., Beaudette N. V., Fasman G. D. Conformational studies of the synthetic precursor-specific region of preproparathyroid hormone. Proc Natl Acad Sci U S A. 1980 Jul;77(7):3983–3987. doi: 10.1073/pnas.77.7.3983. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sanger F., Nicklen S., Coulson A. R. DNA sequencing with chain-terminating inhibitors. Proc Natl Acad Sci U S A. 1977 Dec;74(12):5463–5467. doi: 10.1073/pnas.74.12.5463. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schnaitman C. A. Solubilization of the cytoplasmic membrane of Escherichia coli by Triton X-100. J Bacteriol. 1971 Oct;108(1):545–552. doi: 10.1128/jb.108.1.545-552.1971. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schwartz M. The adsorption of coliphage lambda to its host: effect of variations in the surface density of receptor and in phage-receptor affinity. J Mol Biol. 1976 May 25;103(3):521–536. doi: 10.1016/0022-2836(76)90215-1. [DOI] [PubMed] [Google Scholar]
- Szmelcman S., Schwartz M., Silhavy T. J., Boos W. Maltose transport in Escherichia coli K12. A comparison of transport kinetics in wild-type and lambda-resistant mutants as measured by fluorescence quenching. Eur J Biochem. 1976 May 17;65(1):13–19. doi: 10.1111/j.1432-1033.1976.tb10383.x. [DOI] [PubMed] [Google Scholar]