PrlA suppressor mutations cluster in regions corresponding to three distinct topological domains.

Osborne, R.S.; Silhavy, Thomas J.

doi:10.1002/j.1460-2075.1993.tb06013.x

Cited by 112 publications

(186 citation statements)

References 45 publications

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“…The PrlA4 SecY protein contains two mutations, F286Y and I408N, where the latter is responsible for the suppressor effect (21). To determine if the strong PMF-dependent translocation of the proOmpA tetraarylmethane conjugates is suppressed by the PrlA4 strain we analyzed the translocation of proOmpA conjugated with IsoTAM2.…”

Section: Resultsmentioning

confidence: 99%

Probing the SecYEG translocation pore size with preproteins conjugated with sizable rigid spherical molecules

Bonardi

Halža

Walko

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Protein translocation in Escherichia coli is mediated by the translocase that in its minimal form consists of the protein-conducting channel SecYEG, and the motor protein, SecA. SecYEG forms a narrow pore in the membrane that allows passage of unfolded proteins only. Molecular dynamics simulations suggest that the maximal width of the central pore of SecYEG is limited to 16 Å. To access the functional size of the SecYEG pore, the precursor of outer membrane protein A was modified with rigid spherical tetraarylmethane derivatives of different diameters at a unique cysteine residue. SecYEG allowed the unrestricted passage of the precursor of outer membrane protein A conjugates carrying tetraarylmethanes with diameters up to 18 Å, whereas a 29 Å sized molecule blocked the translocation pore. Translocation of the protein-organic molecule hybrids was strictly proton motive force-dependent and occurred at a single pore. With an average diameter of an unfolded polypeptide chain of 4-6 Å, the pore accommodates structures of at least 22-24 Å, which is vastly larger than the predicted maximal width of a single pore by molecular dynamics simulations.secretion | Sec-system

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Section: Resultsmentioning

confidence: 99%

Probing the SecYEG translocation pore size with preproteins conjugated with sizable rigid spherical molecules

Bonardi

Halža

Walko

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…change to a Lys residue, are conserved in SCY2. Residues that give rise to suppressor mutations in transmembrane 7 of E. coli SecY are also largely conserved in SCY1 and SCY2 (Osborne and Silhavy, 1993). In addition, a critical Tyr residue and L-X-X-Y motif are found in the C termini of both SCY1 and SCY2.…”

Section: Scy1 and Scy2 Perform Different Functionsmentioning

confidence: 99%

Plastids Contain a Second Sec Translocase System with Essential Functions

et al. 2010

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Proteins that are synthesized on cytoplasmic ribosomes but function within plastids must be imported and then targeted to one of six plastid locations. Although multiple systems that target proteins to the thylakoid membranes or thylakoid lumen have been identified, a system that can direct the integration of inner envelope membrane proteins from the stroma has not been previously described. Genetics and localization studies were used to show that plastids contain two different Sec systems with distinct functions. Loss-of-function mutations in components of the previously described thylakoid-localized Sec system, designated as SCY1 (At2g18710), SECA1 (At4g01800), and SECE1 (At4g14870) in Arabidopsis (Arabidopsis thaliana), result in albino seedlings and sucrose-dependent heterotrophic growth. Loss-of-function mutations in components of the second Sec system, designated as SCY2 (At2g31530) and SECA2 (At1g21650) in Arabidopsis, result in arrest at the globular stage and embryo lethality. Promoter-swap experiments provided evidence that SCY1 and SCY2 are functionally nonredundant and perform different roles in the cell. Finally, chloroplast import and fractionation assays and immunogold localization of SCY2-green fluorescent protein fusion proteins in root tissues indicated that SCY2 is part of an envelope-localized Sec system. Our data suggest that SCY2 and SECA2 function in Sec-mediated integration and translocation processes at the inner envelope membrane.

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“…The so-called pd (for protein localization) class of mutants, which are all isolated as suppressors of signal sequence mutations, have been found in SecA (prlD), SccY (pr/A), SecE (prlG) and more recently in SecG (prlH) (see references in [7,[36][37][38]). It has been proposed that the pr/suppressors function not by restoring the recognition of altered signal sequences but rather by preventing the rejection of defective preproteins from the export pathway [39]. According to this hypothesis, SecA, Sec'L SecE and SecG would have a proofreading activitx5 A possible proofreading function has recently been investigated for certain prlA mutants (JPW van der Wolk eta/., unpublished data).…”

Section: Signal Sequence Proofreading At the Initiation Of Translocationmentioning

confidence: 99%

The Sec system

Driessen

Fekkes

Wolk

1998

Current Opinion in Microbiology

159

111

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The Sec system Driessen, A.J.M.; Fekkes, P.; van der Wolk, J.P.W. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Proteins designated to be secreted by Escherichia coil are synthesized with an amino-terminal signal peptide and associate as nascent chains with the export-specific chaperone SecB. Translocation occurs at a multisubunit membrane-bound enzyme termed translocase, which consists of a peripheral preprotein-binding site and an ATPase domain termed SecA, a core heterotrimeric integral membrane protein complex with SecY, SecE and SecG as subunits, and an accessory integral membrane protein complex containing SecD and SecE Major new insights have been gained into the cascade of preprotein targeting events and the enzymatic mechanism of preprotein translocation. It has become clear that preproteins are translocated in a stepwise fashion involving large nucleotide-induced conformational changes of the molecular motor SecA that propels the translocation reaction. Addresses

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PrlA suppressor mutations cluster in regions corresponding to three distinct topological domains.

Cited by 112 publications

References 45 publications

Probing the SecYEG translocation pore size with preproteins conjugated with sizable rigid spherical molecules

Probing the SecYEG translocation pore size with preproteins conjugated with sizable rigid spherical molecules

Plastids Contain a Second Sec Translocase System with Essential Functions

The Sec system

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