Identification of Streptomyces lividans proteins secreted by the twin-arginine translocation pathway following growth with different carbon sources

2008 ◽  
Vol 54 (7) ◽  
pp. 549-558 ◽  
Author(s):  
Julien Guimond ◽  
Rolf Morosoli

Genome-based signal peptide predictions classified Streptomyces coelicolor as the microorganism that secretes the most proteins through the twin-arginine translocation (Tat)-dependent secretion pathway. Availability of a ΔtatC mutant of the closely related strain Streptomyces lividans impaired Tat-dependent protein secretion and enabled identification of many extracellular proteins that are secreted via the Tat pathway. Proteomic techniques were applied to analyze proteins from the supernatants of log-phase cultures. Since the bacterial secretome depends mainly on the carbon sources available during growth, xylose, glucose, chitin, and soil extracts were used. A total of 63 proteins were identified, among which 7 were predicted by the TATscan program, and 20 were not predicted but contained a potential Tat signal motif. Thirteen proteins having no signal sequence could be co-transported by Tat-dependent proteins because the genes that encode these proteins are in close proximity in the genome. Finally, the presence of 23 proteins lacking signal peptides was difficult to explain. More secreted proteins could be identified as Tat substrates in varying carbon sources.

Microbiology ◽  
2005 ◽  
Vol 151 (7) ◽  
pp. 2189-2198 ◽  
Author(s):  
Haiming Li ◽  
Pierre-Étienne Jacques ◽  
Mariana Gabriela Ghinet ◽  
Ryszard Brzezinski ◽  
Rolf Morosoli

The availability of the complete genome sequence of Streptomyces coelicolor A3(2) has allowed the prediction of the Tat-exported proteins of this Gram-positive bacterium. To predict secreted proteins that potentially use the Tat pathway for their secretion, the TATscan program was developed. This program identified 129 putative Tat substrates. To test the validity of these predictions, nine signal sequences, including three which were not identified by existing prediction programs, were selected and fused to the structural xlnC gene in place of its native signal sequence. Xylanase C (XlnC) is a cofactorless enzyme which is secreted in an active form exclusively through the Tat-dependent pathway by Streptomyces lividans. Among the nine chosen signal sequences, seven were shown to be Tat-dependent, one was Sec-dependent and one was probably not a signal sequence. The seven Tat-dependent signal sequences comprised two lipoprotein signal sequences and three sequences not predicted by previous programs. Pulse–chase experiments showed that the precursor-processing rate in the seven transformants was generally slower than wild-type XlnC, indicating that these signal peptides were not equivalent in secretion. This suggested that there might be some incompatibility between the signal peptide and the reporter protein fused to it. To test this possibility, the signal peptides were fused to a cofactorless chitosanase (SCO0677), a Tat-dependent protein validated in this work but structurally different from XlnC. With some fluctuations, similar results were obtained with this enzyme, indicating that the type of folding of the reporter protein had little effect on the Tat secretion process.


2003 ◽  
Vol 185 (9) ◽  
pp. 2811-2819 ◽  
Author(s):  
Natascha Blaudeck ◽  
Peter Kreutzenbeck ◽  
Roland Freudl ◽  
Georg A. Sprenger

ABSTRACT In Escherichia coli, the SecB/SecA branch of the Sec pathway and the twin-arginine translocation (Tat) pathway represent two alternative possibilities for posttranslational translocation of proteins across the cytoplasmic membrane. Maintenance of pathway specificity was analyzed using a model precursor consisting of the mature part of the SecB-dependent maltose-binding protein (MalE) fused to the signal peptide of the Tat-dependent TorA protein. The TorA signal peptide selectively and specifically directed MalE into the Tat pathway. The characterization of a spontaneous TorA signal peptide mutant (TorA*), in which the two arginine residues in the c-region had been replaced by one leucine residue, showed that the TorA*-MalE mutant precursor had acquired the ability for efficiently using the SecB/SecA pathway. Despite the lack of the “Sec avoidance signal,” the mutant precursor was still capable of using the Tat pathway, provided that the kinetically favored Sec pathway was blocked. These results show that the h-region of the TorA signal peptide is, in principle, sufficiently hydrophobic for Sec-dependent protein translocation, and therefore, the positively charged amino acid residues in the c-region represent a major determinant for Tat pathway specificity. Tat-dependent export of TorA-MalE was significantly slower in the presence of SecB than in its absence, showing that SecB can bind to this precursor despite the presence of the Sec avoidance signal in the c-region of the TorA signal peptide, strongly suggesting that the function of the Sec avoidance signal is not the prevention of SecB binding; rather, it must be exerted at a later step in the Sec pathway.


2009 ◽  
Vol 191 (19) ◽  
pp. 5921-5929 ◽  
Author(s):  
Lalitha Biswas ◽  
Raja Biswas ◽  
Christiane Nerz ◽  
Knut Ohlsen ◽  
Martin Schlag ◽  
...  

ABSTRACT In Staphylococcus, the twin-arginine translocation (Tat) pathway is present only in some species and is composed of TatA and TatC. The tatAC operon is associated with the fepABC operon, which encodes homologs to an iron-binding lipoprotein, an iron-dependent peroxidase (FepB), and a high-affinity iron permease. The FepB protein has a typical twin-arginine (RR) signal peptide. The tat and fep operons constitute an entity that is not present in all staphylococcal species. Our analysis was focused on Staphylococcus aureus and S. carnosus strains. Tat deletion mutants (ΔtatAC) were unable to export active FepB, indicating that this enzyme is a Tat substrate. When the RR signal sequence from FepB was fused to prolipase and protein A, their export became Tat dependent. Since no other protein with a Tat signal could be detected, the fepABC-tatAC genes comprise not only a genetic but also a functional unit. We demonstrated that FepABC drives iron import, and in a mouse kidney abscess model, the bacterial loads of ΔtatAC and Δtat-fep mutants were decreased. For the first time, we show that the Tat pathway in S. aureus is functional and serves to translocate the iron-dependent peroxidase FepB.


2004 ◽  
Vol 186 (2) ◽  
pp. 366-373 ◽  
Author(s):  
Matthew P. DeLisa ◽  
Philip Lee ◽  
Tracy Palmer ◽  
George Georgiou

ABSTRACT Overexpression of either heterologous or homologous proteins that are routed to the periplasm via the twin-arginine translocation (Tat) pathway results in a block of export and concomitant accumulation of the respective protein precursor in the cytoplasm. Screening of a plasmid-encoded genomic library for mutants that confer enhanced export of a TorA signal sequence (ssTorA)-GFP-SsrA fusion protein, and thus result in higher cell fluorescence, yielded the pspA gene encoding phage shock protein A. Coexpression of pspA relieved the secretion block observed with ssTorA-GFP-SsrA or upon overexpression of the native Tat proteins SufI and CueO. A similar effect was observed with the Synechocystis sp. strain PCC6803 PspA homologue, VIPP1, indicating that the role of PspA in Tat export may be phylogenetically conserved. Mutations in Tat components that completely abolish export result in a marked induction of PspA protein synthesis, consistent with its proposed role in enhancing protein translocation via Tat.


2008 ◽  
Vol 191 (1) ◽  
pp. 196-202 ◽  
Author(s):  
Robyn T. Eijlander ◽  
Jan D. H. Jongbloed ◽  
Oscar P. Kuipers

ABSTRACT Protein translocation via the twin arginine translocation (TAT) pathway is characterized by the translocation of prefolded proteins across the hydrophobic lipid bilayer of the membrane. In Bacillus subtilis, two different Tat translocases are involved in this process, and both display different substrate specificities: PhoD is secreted via TatAdCd, whereas YwbN is secreted via TatAyCy. It was previously assumed that both TatAy and TatCy are essential for the translocation of the YwbN precursor. Through complementation studies, we now show that TatAy can be functionally replaced by TatAd when the latter is offered to the cells in excess amounts. Moreover, under conditions of overproduction, TatAdCd, in contrast to TatAyCy, shows an increased tolerance toward the acceptance of various Tat-dependent proteins.


2021 ◽  
Author(s):  
Umesh K Bageshwar ◽  
Antara DattaGupta ◽  
Siegfried M Musser

The twin-arginine translocation (Tat) pathway transports folded proteins across energetic membranes. Numerous Tat substrates contain co-factors that are inserted before transport with the assistance of redox enzyme maturation proteins (REMPs), which bind to the signal peptide of precursor proteins. How signal peptides are transferred from a REMP to a binding site on the Tat receptor complex remains unknown. Since the signal peptide mediates both interactions, possibilities include: i) a coordinated hand-off mechanism; or ii) a diffusional search after REMP dissociation. We investigated the binding interaction between substrates containing the TorA signal peptide (spTorA) and its cognate REMP, TorD, and the effect of TorD on the in vitrotransport of such substrates. We found that Escherichia coli TorD is predominantly a monomer at low micromolar concentrations (dimerization KD > 50 M), and this monomer binds reversibly to spTorA (KD 1 M). While TorD binds to membranes (KD 100 nM), it has no apparent affinity for Tat translocons and it inhibits binding of a precursor substrate to the membrane. TorD has a minimal effect on substrate transport by the Tat system, being mildly inhibitory at high concentrations. These data are consistent with a model in which the REMP-bound signal peptide is shielded from recognition by the Tat translocon, and spontaneous dissociation of the REMP allows the substrate to engage the Tat machinery. Thus, the REMP does not assist with targeting to the Tat translocon, but rather temporarily shields the signal peptide.


2001 ◽  
Vol 183 (2) ◽  
pp. 604-610 ◽  
Author(s):  
Natascha Blaudeck ◽  
Georg A. Sprenger ◽  
Roland Freudl ◽  
Thomas Wiegert

ABSTRACT The bacterial twin arginine translocation (Tat) pathway translocates across the cytoplasmic membrane folded proteins which, in most cases, contain a tightly bound cofactor. Specific amino-terminal signal peptides that exhibit a conserved amino acid consensus motif, S/T-R-R-X-F-L-K, direct these proteins to the Tat translocon. The glucose-fructose oxidoreductase (GFOR) ofZymomonas mobilis is a periplasmic enzyme with tightly bound NADP as a cofactor. It is synthesized as a cytoplasmic precursor with an amino-terminal signal peptide that shows all of the characteristics of a typical twin arginine signal peptide. However, GFOR is not exported to the periplasm when expressed in the heterologous host Escherichia coli, and enzymatically active pre-GFOR is found in the cytoplasm. A precise replacement of the pre-GFOR signal peptide by an authentic E. coli Tat signal peptide, which is derived from pre-trimethylamine N-oxide (TMAO) reductase (TorA), allowed export of GFOR, together with its bound cofactor, to the E. coli periplasm. This export was inhibited by carbonyl cyanide m-chlorophenylhydrazone, but not by sodium azide, and was blocked in E. coli tatC andtatAE mutant strains, showing that membrane translocation of the TorA-GFOR fusion protein occurred via the Tat pathway and not via the Sec pathway. Furthermore, tight cofactor binding (and therefore correct folding) was found to be a prerequisite for proper translocation of the fusion protein. These results strongly suggest that Tat signal peptides are not universally recognized by different Tat translocases, implying that the signal peptides of Tat-dependent precursor proteins are optimally adapted only to their cognate export apparatus. Such a situation is in marked contrast to the situation that is known to exist for Sec-dependent protein translocation.


2019 ◽  
Author(s):  
Deepanjan Ghosh ◽  
Sureshkumar Ramasamy

AbstractRedox – enzyme maturation proteins (REMP) ensure co-factor loading and folding of proteins targeted to the twin-arginine translocation (Tat) pathway. The details of the interaction of a REMP with the corresponding signal sequence of its substrate are not well understood. Here, we demonstrate the features of the signal sequence for the Tat substrate DmsA (ssDmsA) responsible for complex formation with its REMP, DmsD, and with the Tat membrane complex TatB & TatC (TatBC). A heterologously expressed ssDmsA/DmsD complex forms two stochiometric populations corresponding to monomeric and dimeric forms of the complex. The monomeric complex has a higher affinity for the TatBC complex than the dimeric, which imply higher level regulation process to ensure the maturation of protein before translocation. Results from various binding studies yielded the shortest signal peptide required for ssDmsA/DmsA interaction and the region responsible for the TatBC interaction. Further experiments like alanine scanning in this peptide highlight the possible residues that are essential for this complex formation.


2008 ◽  
Vol 75 (3) ◽  
pp. 603-607 ◽  
Author(s):  
Yoshimi Kikuchi ◽  
Hiroshi Itaya ◽  
Masayo Date ◽  
Kazuhiko Matsui ◽  
Long-Fei Wu

ABSTRACT The twin-arginine translocation (Tat) pathway in Corynebacterium glutamicum has been described previously. The minimal functional Tat system in C. glutamicum required TatA and TatC but did not require TatB, although this component was required for maximal efficiency of Tat-dependent secretion. We previously demonstrated that Chryseobacterium proteolyticum pro-protein glutaminase (pro-PG) and Streptomyces mobaraensis pro-transglutaminase (pro-TG) could be secreted via the Tat pathway in C. glutamicum. Here we report that the amounts of pro-PG secreted were more than threefold larger when TatC or TatAC was overexpressed, and there was a further threefold increase when TatABC was overexpressed. These results show that the amount of TatC protein is the first bottleneck and the amount of TatB protein is the second bottleneck in Tat-dependent protein secretion in C. glutamicum. In addition, the amount of pro-TG that accumulated via the Tat pathway when TatABC was overexpressed with the TorA signal peptide in C. glutamicum was larger than the amount that accumulated via the Sec pathway. We concluded that TatABC overexpression improves Tat-dependent pro-PG and pro-TG secretion in C. glutamicum.


Sign in / Sign up

Export Citation Format

Share Document