Direct Evidence That the Proton Motive Force Inhibits Membrane Translocation of Positively Charged Residues within Membrane Proteins

Schuenemann, Tracy A.; Delgado-Nixon, Vondolee M.; Dalbey, Ross E.

doi:10.1074/jbc.274.11.6855

Cited by 36 publications

(37 citation statements)

References 49 publications

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“…For example, the residues that are involved in pH sensing were found in the cytoplasmic HAMP domain (Umemura et al, 2002), whereas residues that might control the transducer mobility in the membrane in response to changes in the electrochemical proton gradient are likely to be located in the membrane/cytoplasm interface (i.e. between the transmembrane helix and the HAMP domain), as suggested for other transmembrane proteins (Schuenemann et al, 1999). …”

Section: Discussionmentioning

confidence: 99%

Aer and Tsr guide Escherichia coli in spatial gradients of oxidizable substrates

et al. 2003

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The Aer and Tsr chemoreceptors in Escherichia coli govern tactic responses to oxygen and redox potential that are parts of an overall behaviour known as energy taxis. They are also proposed to mediate responses to rapidly utilized carbon sources, glycerol and succinate, via the energy taxis mechanism. In this study, the Aer and Tsr proteins were individually expressed in an 'alltransducer-knockout' strain of E. coli and taxis was analysed in gradients of various oxidizable carbon sources. In addition to the known response to glycerol and succinate, it was found that Aer directed taxis towards ribose, galactose, maltose, malate, proline and alanine as well as the phosphotransferase system (PTS) carbohydrates glucose, mannitol, mannose, sorbitol and fructose, but not to aspartate, glutamate, glycine and arabinose. Tsr directed taxis towards sugars (including those transported by the PTS), but not to organic acids or amino acids. When a mutated Aer protein unable to bind the FAD cofactor was expressed in the receptor-less strain, chemotaxis was not restored to any substrate. Aer appears to mediate responses to rapidly oxidizable substrates, whether or not they are effective growth substrates, whereas Tsr appears to mediate taxis to substrates that support maximal growth, whether or not they are rapidly oxidizable. This correlates with the hypothesis that Aer and Tsr sense redox and proton motive force, respectively. Taken together, the results demonstrate that Aer and Tsr mediate responses to a broad range of chemicals and their attractant repertoires overlap with those of specialized chemoreceptors, namely Trg (ribose, galactose) and Tar (maltose).

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Section: Discussionmentioning

confidence: 99%

Aer and Tsr guide Escherichia coli in spatial gradients of oxidizable substrates

et al. 2003

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“…To carry out this test, we examined two Procoat mutants, which previously have been shown to insert independent of the electrochemical membrane potential (26,29). We found that membrane insertion of both mutants is YidC-dependent (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…3A shows that 0PCLep is inhibited under conditions in which YidC is depleted, while in the presence of YidC, 0PCLep inserts across the membrane and is processed by leader peptidase. Likewise, the potential-independent ProcoatLep mutant, PCLep (0) (29), without any charged residues in the periplasmic region was also dependent on YidC (Fig. 3B).…”

Section: Yidc Functions To Promote Membrane Insertion Of Both Membranmentioning

confidence: 99%

Function of YidC for the Insertion of M13 Procoat Protein inEscherichia coli

Samuelson¹,

Jiang²,

Liang³

et al. 2001

Journal of Biological Chemistry

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128

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The membrane insertion of the Sec-independent M13 Procoat protein in bacteria requires the membrane electrochemical potential and the integral membrane protein YidC. We show here that YidC is involved in the translocation but not in the targeting of the Procoat protein, because we found the protein was partitioned into the membrane in the absence of YidC. YidC can function also to promote membrane insertion of Procoat mutants that insert independently of the membrane potential, proving that the effect of YidC depletion is not due to a dissipation of the membrane potential. We also found that YidC is absolutely required for Sec-dependent translocation of a long periplasmic loop of a mutant Procoat in which the periplasmic region has been extended from 20 to 194 residues. Furthermore, when Secdependent membrane proteins with large periplasmic domains were overproduced under YidC-limited conditions, we found that the exported proteins pro-OmpA and pre-peptidoglycan-associated lipoprotein accumulated in the cytoplasm. This suggests for Sec-dependent proteins that YidC functions at a late stage in membrane insertion, after the Sec translocase interacts with the translocating membrane protein. These studies are consistent with the understanding that YidC cooperates with the Sec translocase for membrane translocation and that YidC is required for clearing the protein-conducting channel.

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“…SKP1101 and SKP1102 were transformed with pINGE-Lep (Table 1) and grown as described above prior to the expression of Lep being induced with arabinose. After 2 h at the nonpermissive temperature, cells were pulse-labeled and the protease accessibility of the large periplasmic domain of Lep was measured as previously described (56).…”

Section: Methodsmentioning

confidence: 99%

“…SKP1101 and SKP1102 were transformed with pINGE-Lep (15), encoding leader peptidase (Lep) under arabinose control. Following induction of Lep synthesis at both 30 and 42°C, control and mutant cells were pulse-labeled, and the accessibility of the large periplasmic domain of Lep to protease digestion was determined (56).…”

Section: Vol 184 2002 Temperature-sensitive Ffh Mutant 2647mentioning

confidence: 99%

Functional Analysis of the Signal Recognition Particle inEscherichia coliby Characterization of a Temperature-SensitiveffhMutant

et al. 2002

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The Ffh protein of Escherichia coli is a 48-kDa polypeptide that is homologous to the SRP54 subunit of the eukaryotic signal recognition particle (SRP). Efforts to understand the function of Ffh in bacteria have depended largely on the use of E. coli strains that allow depletion of the wild-type gene product. As an alternative approach to studying Ffh, a temperature-sensitive ffh mutant was isolated. The ffh-10(Ts) mutation results in two amino acid changes in conserved regions of the Ffh protein, and characterization of the mutant revealed that the cells rapidly lose viability at the nonpermissive temperature of 42°C as well as show reduced growth at the permissive temperature of 30°C. While the ffh mutant is defective in insertion of inner membrane proteins, the export of proteins with cleavable signal sequences is not impaired. The mutant also shows elevated expression of heat shock proteins and accumulates insoluble proteins, especially at 42°C. It was further observed that the temperature sensitivity of the ffh mutant was suppressed by overproduction of 4.5S RNA, the RNA component of the bacterial SRP, by stabilizing the thermolabile protein. Collectively, these results are consistent with a model in which Ffh is required only for localization of proteins integral to the cytoplasmic membrane and suggest new genetic approaches to the study of how the structure of the SRP contributes to its function.The signal recognition particle (SRP) is a ribonucleoprotein complex that was first described for eukaryotic cells as being important for targeting secretory proteins and integral membrane proteins to the translocation apparatus (67, 68; for a recent review see reference 27). Following the molecular characterization of a 54-kDa protein component of the SRP from mammals (SRP54), it was discovered that Escherichia coli encodes a protein with striking homology to this SRP subunit (7, 52). The gene encoding this protein was identified as an open reading frame with no known function (13) and was termed ffh for "fifty-four homologue." Amino acids with a high degree of conservation were located throughout the protein and included an amino-terminal domain of unknown function, a GTP binding domain (G domain), and a methionine-rich carboxyterminal M domain. These features led to a model of Ffh function in which the M domain binds to signal sequences of exported proteins by contacts between the relatively flexible side chains of methionine and the hydrophobic amino acids of a typical export signal (7).Other E. coli gene products were also discovered that displayed significant homologies with components of the eukaryotic SRP. Specifically, the product of ftsY, a poorly characterized gene thought to be important for cell division (19), has homology with the ␣ subunit of the SRP receptor (SR␣) from higher cells. FtsY also possesses a G domain that is highly homologous to that of Ffh (7). Furthermore, the 7S RNA component of the mammalian SRP has sequence and structural similarities with a 4.5S RNA species from E. coli (50). As ...

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Direct Evidence That the Proton Motive Force Inhibits Membrane Translocation of Positively Charged Residues within Membrane Proteins

Cited by 36 publications

References 49 publications

Aer and Tsr guide Escherichia coli in spatial gradients of oxidizable substrates

Aer and Tsr guide Escherichia coli in spatial gradients of oxidizable substrates

Function of YidC for the Insertion of M13 Procoat Protein inEscherichia coli

Functional Analysis of the Signal Recognition Particle inEscherichia coliby Characterization of a Temperature-SensitiveffhMutant

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