A Little Help from My Friends: Quality Control of Presecretory Proteins in Bacteria

Fisher, Adam C.; DeLisa, Matthew P.

doi:10.1128/jb.186.22.7467-7473.2004

Cited by 24 publications

(19 citation statements)

References 83 publications

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“…Instead, these proteins interact, together with cytosolic proteins, during the late co-translational phase or post-translationally with SecB, which keeps them in a translocation-competent non-native state. SecB then selectively transfers secretory proteins by direct interaction to SecA, which shuttles them to the translocon [50]. In contrast to prior assumptions, SecA is active in substrate association as a monomer, at least in the membrane-and translocon-interacting state.…”

Section: Bacterial Chaperonesmentioning

confidence: 77%

A cradle for new proteins: trigger factor at the ribosome

Maier

Ferbitz

Deuerling

et al. 2005

Current Opinion in Structural Biology

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Newly synthesized proteins leave the ribosome through a narrow tunnel in the large subunit. During ongoing synthesis, nascent protein chains are particularly sensitive to aggregation and degradation because they emerge from the ribosome in an unfolded state. In bacteria, the first protein to interact with nascent chains and facilitate their folding is the ribosomeassociated chaperone trigger factor. Recently, crystal structures of trigger factor and of its ribosome-binding domain in complex with the large ribosomal subunit revealed that the chaperone adopts an extended 'dragon-shaped' fold with a large hydrophobic cradle, which arches over the exit of the ribosomal tunnel and shields newly synthesized proteins. These structural results, together with recent biochemical data on trigger factor and its interplay with other chaperones and factors that interact with the nascent chain, provide a comprehensive view of the role of trigger factor during cotranslational protein folding.

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Section: Bacterial Chaperonesmentioning

confidence: 77%

A cradle for new proteins: trigger factor at the ribosome

Maier

Ferbitz

Deuerling

et al. 2005

Current Opinion in Structural Biology

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“…In these instances, it is envisioned that general folding catalysts may participate in the folding and proofreading of Tat substrates by sequestering misfolded proteins from the translocon until correct folding or proteolytic degradation has occurred. 34 Several lines of evidence implicate a role for general molecular chaperones in bacterial Tat transport including: (1) the chaperone trigger factor (TF) binds extensively to the TorA and SufI signal peptides, although depletion or over-expression of TF had little effect on the kinetics and efficiency of the Tat export process; 35 (2) GroEL was found to affect Tat-specific hydrogenase-1 maturation and assembly, 36 and was found to associate with the Tat-specific amidase AmiA; 37 (3) DnaK binds specifically to the Tat leader peptide of DmsA; 25 (4) members of the chaperone cascade including TF, DnaK-DnaJ-GrpE and GroEL interact with the Tat-specific REMP DmsD 38 ; and finally, (5) over-expression of DnaKDnaJ-GrpE, GroEL-GroES and TF has been shown to enhance the transport of the Tat substrate preproPAC. 39 In addition to the direct involvement of cytoplasmic chaperones, a number of indirect observations suggest that factors other than TatABC are involved in Tat transport.…”

Section: Introductionmentioning

confidence: 97%

An Essential Role for the DnaK Molecular Chaperone in Stabilizing Over-expressed Substrate Proteins of the Bacterial Twin-arginine Translocation Pathway

Pérez-Rodríguez

Fisher

Perlmutter

et al. 2007

Journal of Molecular Biology

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“…Preproteins must be in an unfolded conformation to be competent for Sec export. Cytosolic chaperones and the process of translocation itself can help keep preproteins in an unfolded and translocation-competent state (16)(17)(18). After export, the signal sequence is cleaved from the preprotein by signal peptidases to yield the mature protein (19).…”

mentioning

confidence: 99%

Protein Export by the Mycobacterial SecA2 System Is Determined by the Preprotein Mature Domain

Feltcher

Gibbons

Ligon

et al. 2012

Journal of Bacteriology

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At the core of the bacterial general secretion (Sec) pathway is the SecA ATPase, which powers translocation of unfolded preproteins containing Sec signal sequences through the SecYEG membrane channel. Mycobacteria have two nonredundant SecA homologs: SecA1 and SecA2. While the essential SecA1 handles "housekeeping" export, the nonessential SecA2 exports a subset of proteins and is required for Mycobacterium tuberculosis virulence. Currently, it is not understood how SecA2 contributes to Sec export in mycobacteria. In this study, we focused on identifying the features of two SecA2 substrates that target them to SecA2 for export, the Ms1704 and Ms1712 lipoproteins of the model organism Mycobacterium smegmatis. We found that the mature domains of Ms1704 and Ms1712, not the N-terminal signal sequences, confer SecA2-dependent export. We also demonstrated that the lipid modification and the extreme N terminus of the mature protein do not impart the requirement for SecA2 in export. We further showed that the Ms1704 mature domain can be efficiently exported by the twin-arginine translocation (Tat) pathway. Because the Tat system exports only folded proteins, this result implies that SecA2 substrates can fold in the cytoplasm and suggests a putative role of SecA2 in enabling export of such proteins. Thus, the mycobacterial SecA2 system may represent another way that bacteria solve the problem of exporting proteins that can fold in the cytoplasm.

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A Little Help from My Friends: Quality Control of Presecretory Proteins in Bacteria

Cited by 24 publications

References 83 publications

A cradle for new proteins: trigger factor at the ribosome

A cradle for new proteins: trigger factor at the ribosome

An Essential Role for the DnaK Molecular Chaperone in Stabilizing Over-expressed Substrate Proteins of the Bacterial Twin-arginine Translocation Pathway

Protein Export by the Mycobacterial SecA2 System Is Determined by the Preprotein Mature Domain

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