The Escherichia coli thioredoxin homolog YbbN/Trxsc is a chaperone and a weak protein oxidoreductase

Caldas, Thérèse; Malki, Abderrahim; Kern, Renée; Abdallah, Jad; Richarme, Gilbert

doi:10.1016/j.bbrc.2006.03.028

Cited by 21 publications

(21 citation statements)

References 37 publications

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“…BSA, a nonchaperone control protein, does not offer any protection. Thioredoxin is well known for its thermoresistance (57) and in some cases has been described as a chaperone (58). The inactivation and aggregation of GAPDH in the presence of thioredoxin are still observed, although this protein slows down the process.…”

Section: Discussionmentioning

confidence: 99%

CP12 from Chlamydomonas reinhardtii, a Permanent Specific “Chaperone-like” Protein of Glyceraldehyde-3-phosphate Dehydrogenase

Erales

Lignon

Gontero

2009

Journal of Biological Chemistry

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A new role is reported for CP12, a highly unfolded and flexible protein, mainly known for its redox function with A 4 glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Both reduced and oxidized CP12 can prevent the in vitro thermal inactivation and aggregation of GAPDH from Chlamydomonas reinhardtii. This mechanism is thus not redox-dependent. The protection is specific to CP12, because other proteins, such as bovine serum albumin, thioredoxin, and a general chaperone, Hsp33, do not fully prevent denaturation of GAPDH. Furthermore, CP12 acts as a specific chaperone, since it does not protect other proteins, such as catalase, alcohol dehydrogenase, or lysozyme. The interaction between CP12 and GAPDH is necessary to prevent the aggregation and inactivation, since the mutant C66S that does not form any complex with GAPDH cannot accomplish this protection. Unlike the C66S mutant, the C23S mutant that lacks the N-terminal bridge is partially able to protect and to slow down the inactivation and aggregation. Tryptic digestion coupled to mass spectrometry confirmed that the S-loop of GAPDH is the interaction site with CP12. Thus, CP12 not only has a redox function but also behaves as a specific "chaperone-like protein" for GAPDH, although a stable and not transitory interaction is observed. This new function of CP12 may explain why it is also present in complexes involving A 2 B 2 GAPDHs that possess a regulatory C-terminal extension (GapB subunit) and therefore do not require CP12 to be redox-regulated.CP12 is a small 8.2-kDa protein present in the chloroplasts of most photosynthetic organisms, including cyanobacteria (1, 2), higher plants (3), the diatom Asterionella formosa (4, 5), and green (1) and red algae (6). It allows the formation of a supramolecular complex between phosphoribulokinase (EC 2.7.1.19) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), 3 two key enzymes of the Calvin cycle pathway, and was recently shown to interact with fructose bisphosphate aldolase, another enzyme of the Calvin cycle pathway (7). The phosphoribulokinase⅐GAPDH⅐CP12 complex has been extensively studied in Chlamydomonas reinhardtii (8, 9) and in Arabidopsis thaliana (10, 11). In the green alga C. reinhardtii, the interaction between CP12 and GAPDH is strong (8). GAPDH may exist as a homotetramer composed of four GapA subunits (A 4 ) in higher plants, cyanobacteria, and green and red algae (6, 12), but in higher plants, it can also exist as a heterotetramer (A 2 B 2 ), composed of two subunits, GapA and GapB (13,14). GapB, up to now, has exclusively been found in Streptophyta, but recently two prasinophycean green algae, Ostreococcus tauri and Ostreococcus lucimarinus, were also shown to possess a GapB gene, whereas CP12 is missing (15). The GapB subunit is similar to the GapA subunit but has a C-terminal extension containing two redox-regulated cysteine residues (16). Thus, although the A 4 GAPDHs lack these regulatory cysteine residues (13,14,(17)(18)(19)(20), they are also redox-regulated through its interaction with CP12, ...

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Section: Discussionmentioning

confidence: 99%

CP12 from Chlamydomonas reinhardtii, a Permanent Specific “Chaperone-like” Protein of Glyceraldehyde-3-phosphate Dehydrogenase

Erales

Lignon

Gontero

2009

Journal of Biological Chemistry

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“…YbbN was initially reported to possess a weak thiol-disulfide protein oxidoreductase activity in an in vitro RNase A disulfide isomerization assay (10). However, the conserved thioredoxin CXXC active site motif necessary for this activity is mutated to a SXXC sequence in E. coli YbbN.…”

Section: Thioredoxin (Trx)mentioning

confidence: 99%

“…Caldas et al (10) found that YbbN alone is able to facilitate the refolding of urea-denatured citrate synthase (CS), ␣-glucosidase or ␤-clamp DnaN in vitro with an efficiency comparable to chaperones like DnaK and other heat shock proteins. However, a contradictory result was briefly * This work was supported, in whole or in part, by National Institutes of Health mentioned by Pan and Bardwell (5) using CS as a substrate.…”

Section: Thioredoxin (Trx)mentioning

confidence: 99%

“…However, the conserved thioredoxin CXXC active site motif necessary for this activity is mutated to a SXXC sequence in E. coli YbbN. The reported oxidoreductase activity was proposed to result from a non-canonical active site comprising the conserved Cys-38 and a distal but more highly conserved Cys-63 as a second redox active cysteine residue (10). However, a subsequent report from the same group noted that the in vivo relevance of this weak activity is uncertain, as a ybbN-deficient strain of E. coli does not display increased sensitivity to oxidative stress, and no clear evidence was found for YbbN oxidoreductase activity in vivo (8).…”

Section: Thioredoxin (Trx)mentioning

confidence: 99%

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Escherichia coli Thioredoxin-like Protein YbbN Contains an Atypical Tetratricopeptide Repeat Motif and Is a Negative Regulator of GroEL

Lin

Wilson

2011

Journal of Biological Chemistry

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Many proteins contain a thioredoxin (Trx)-like domain fused with one or more partner domains that diversify protein function by the modular construction of new molecules. The Escherichia coli protein YbbN is a Trx-like protein that contains a C-terminal domain with low homology to tetratricopeptide repeat motifs. YbbN has been proposed to act as a chaperone or co-chaperone that aids in heat stress response and DNA synthesis. We report the crystal structure of YbbN, which is an elongated molecule with a mobile Trx domain and four atypical tetratricopeptide repeat motifs. The Trx domain lacks a canonical CXXC active site architecture and is not a functional oxidoreductase. A variety of proteins in E. coli interact with YbbN, including multiple ribosomal protein subunits and a strong interaction with GroEL. YbbN acts as a mild inhibitor of GroESL chaperonin function and ATPase activity, suggesting that it is a negative regulator of the GroESL system. Combined with previous observations that YbbN enhances the DnaK-DnaJ-GrpE chaperone system, we propose that YbbN coordinately regulates the activities of these two prokaryotic chaperones, thereby helping to direct client protein traffic initially to DnaK. Therefore, YbbN may play a role in integrating the activities of different chaperone pathways in E. coli and related bacteria.

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“…coli (8), plants contain 2 large Trx families, namely the Trx and Trx-like proteins (9). Members of the Trx family have a distinct Trx motif, whereas the Trx-like protein family has a second functional domain in addition to the Trx motif (9).…”

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confidence: 99%

Heat-shock dependent oligomeric status alters the function of a plant-specific thioredoxin-like protein, AtTDX

Lee¹,

Lee

Jang

et al. 2009

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

107

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We found that Arabidopsis AtTDX, a heat-stable and plant-specific thioredoxin (Trx)-like protein, exhibits multiple functions, acting as a disulfide reductase, foldase chaperone, and holdase chaperone. The activity of AtTDX, which contains 3 tetratricopeptide repeat (TPR) domains and a Trx motif, depends on its oligomeric status. The disulfide reductase and foldase chaperone functions predominate when AtTDX occurs in the low molecular weight (LMW) form, whereas the holdase chaperone function predominates in the high molecular weight (HMW) complexes. Because deletion of the TPR domains results in a significant enhancement of AtTDX disulfide reductase activity and complete loss of the holdase chaperone function, our data suggest that the TPR domains of AtTDX block the active site of Trx and play a critical role in promoting the holdase chaperone function. The oligomerization status of AtTDX is reversibly regulated by heat shock, which causes a transition from LMW to HMW complexes with concomitant functional switching from a disulfide reductase and foldase chaperone to a holdase chaperone. Overexpression of AtTDX in Arabidopsis conferred enhanced heat shock resistance to plants, primarily via its holdase chaperone activity.disulfide reductase ͉ foldase chaperone ͉ holdase chaperone ͉ functional switching ͉ Yedox

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The Escherichia coli thioredoxin homolog YbbN/Trxsc is a chaperone and a weak protein oxidoreductase

Cited by 21 publications

References 37 publications

CP12 from Chlamydomonas reinhardtii, a Permanent Specific “Chaperone-like” Protein of Glyceraldehyde-3-phosphate Dehydrogenase

CP12 from Chlamydomonas reinhardtii, a Permanent Specific “Chaperone-like” Protein of Glyceraldehyde-3-phosphate Dehydrogenase

Escherichia coli Thioredoxin-like Protein YbbN Contains an Atypical Tetratricopeptide Repeat Motif and Is a Negative Regulator of GroEL

Heat-shock dependent oligomeric status alters the function of a plant-specific thioredoxin-like protein, AtTDX

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