Mutations in Subunits of the Escherichia coli Twin-arginine Translocase Block Function via Differing Effects on Translocation Activity or Tat Complex Structure

Barrett, Claire M.L.; Mangels, Dorothea; Robinson, Colin

doi:10.1016/j.jmb.2005.01.026

Cited by 30 publications

(38 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1). Several of these conserved residues had previously been shown to be important for TatA function in E. coli (43)(44)(45)(46)(47)(48)(49). Residues in TatAy were substituted with Ala, except for Pro-2, which was also replaced with Asp, and Ala-31, which was replaced with Gly.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Salt Sensitivity of Minimal Twin Arginine Translocases

Ploeg

Barnett

Vasisht

et al. 2011

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

Background: Minimal twin arginine preprotein translocases consist of TatA and TatC subunits. Results: Here we show that various mutated and wild-type minimal Tat translocases are salt-sensitive. Conclusion: Salt-sensitive electrostatic interactions seem to have critical roles in the preprotein translocation activity of minimal Tat translocases. Significance: Our results represent first experimental evidence for an important role of salt-sensitive electrostatic interactions in Tat translocation.

show abstract

Section: Resultsmentioning

confidence: 99%

“…The structure-function relationships in the TatA and TatB subunits of the TatABC translocase from E. coli have been studied in great detail (43)(44)(45)(46)(47)(48)(49). In contrast, relatively little is known about the bifunctional TatA subunits that are part of the TatAC translocases of Gram-positive bacteria.…”

mentioning

confidence: 99%

Salt Sensitivity of Minimal Twin Arginine Translocases

Ploeg

Barnett

Vasisht

et al. 2011

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

show abstract

“…Consistent with this general conclusion is the fact that the L3 residue Thr-275 directed strong cpTatC-cpTatC cross-linking (Figure 6), the E. coli TatC P3 residue Asp-211 directed photo-cross-linking to TatA (Tha4 ortholog) (Zoufaly et al, 2012), and the TM3-proximal P2 region residue 150 of E. coli TatC directed cross-linking to TatB and TatA (Zoufaly et al, 2012) Mutations in L1 resulted in complete loss of receptor complex and absence of any endogenous cpTatC in the purified mutant cpTatC ( Figure 5). The E. coli TatC periplasmic loop P1 (comparable to L1) is also hypersensitive to mutation (Kneuper et al, 2012) and at least one mutant in P1, P48A, resulted in loss of receptor complex (Barrett et al, 2005). Also of interest is that L1 Cys substitution directed strong cpTatC-cpTatC cross-linking (Figure 6), and a P1 residue of E. coli TatC directed photo-crosslinking to adjacent TatC (Zoufaly et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

“…One approach to address this combines mutagenesis with biochemical characterization and protein-protein interaction studies. This approach has been conducted to some extent with the Escherichia coli Tat system (Allen et al, 2002;Buchanan et al, 2002;Barrett et al, 2005;McDevitt et al, 2006;Holzapfel et al, 2007), but not with the plant Tat system owing to the relative difficulty of mutagenesis and gene replacement.…”

Section: Introductionmentioning

confidence: 99%

Mapping the Signal Peptide Binding and Oligomer Contact Sites of the Core Subunit of the Pea Twin Arginine Protein Translocase

Cline

2013

The Plant Cell

View full text Add to dashboard Cite

Twin arginine translocation (Tat) systems of thylakoid and bacterial membranes transport folded proteins using the proton gradient as the sole energy source. Tat substrates have hydrophobic signal peptides with an essential twin arginine (RR) recognition motif. The multispanning cpTatC plays a central role in Tat operation: It binds the signal peptide, directs translocase assembly, and may facilitate translocation. An in vitro assay with pea (Pisum sativum) chloroplasts was developed to conduct mutagenesis and analysis of cpTatC functions. Ala scanning mutagenesis identified mutants defective in substrate binding and receptor complex assembly. Mutations in the N terminus (S1) and first stromal loop (S2) caused specific defects in signal peptide recognition. Cys matching between substrate and imported cpTatC confirmed that S1 and S2 directly and specifically bind the RR proximal region of the signal peptide. Mutations in four lumen-proximal regions of cpTatC were defective in receptor complex assembly. Copurification and Cys matching analyses suggest that several of the lumen proximal regions may be important for cpTatC-cpTatC interactions. Surprisingly, RR binding domains of adjacent cpTatCs directed strong cpTatC-cpTatC cross-linking. This suggests clustering of binding sites on the multivalent receptor complex and explains the ability of Tat to transport cross-linked multimers. Transport of substrate proteins cross-linked to the signal peptide binding site tentatively identified mutants impaired in the translocation step.

show abstract

“…The size of isolated TatA complexes varies between about 100 and 700 kDa [70,85,100,103]. Homo-oligomers of TatA clearly exist in vivo as shown by cysteine cross-linking [37] and fluorescent labelling techniques [94,104], even at wild-type expression levels [104].…”

Section: The Components Of Tat Translocases (A) Homologues Of Tatc Anmentioning

confidence: 99%

Twin-arginine-dependent translocation of folded proteins

Fröbel

Rose

Müller

2012

Phil. Trans. R. Soc. B

View full text Add to dashboard Cite

Twin-arginine translocation (Tat) denotes a protein transport pathway in bacteria, archaea and plant chloroplasts, which is specific for precursor proteins harbouring a characteristic twin-arginine pair in their signal sequences. Many Tat substrates receive cofactors and fold prior to translocation. For a subset of them, proofreading chaperones coordinate maturation and membrane-targeting. Tat translocases comprise two kinds of membrane proteins, a hexahelical TatC-type protein and one or two members of the single-spanning TatA protein family, called TatA and TatB. TatC-and TatAtype proteins form homo-and hetero-oligomeric complexes. The subunits of TatABC translocases are predominantly recovered from two separate complexes, a TatBC complex that might contain some TatA, and a homomeric TatA complex. TatB and TatC coordinately recognize twin-arginine signal peptides and accommodate them in membrane-embedded binding pockets. Advanced binding of the signal sequence to the Tat translocase requires the proton-motive force (PMF) across the membranes and might involve a first recruitment of TatA. When targeted in this manner, folded twin-arginine precursors induce homo-oligomerization of TatB and TatA. Ultimately, this leads to the formation of a transmembrane protein conduit that possibly consists of a pore-like TatA structure. The translocation step again is dependent on the PMF.

show abstract

Mutations in Subunits of the Escherichia coli Twin-arginine Translocase Block Function via Differing Effects on Translocation Activity or Tat Complex Structure

Cited by 30 publications

References 32 publications

Salt Sensitivity of Minimal Twin Arginine Translocases

Salt Sensitivity of Minimal Twin Arginine Translocases

Mapping the Signal Peptide Binding and Oligomer Contact Sites of the Core Subunit of the Pea Twin Arginine Protein Translocase

Twin-arginine-dependent translocation of folded proteins

Contact Info

Product

Resources

About