Identification of a gene encoding a thioredoxin-like product necessary for cytochrome c biosynthesis and symbiotic nitrogen fixation in Rhizobium leguminosarum

Vargas, Carmen Regla; Wu, Guanhui; Davies, A.M.C.; Downie, J. A.

doi:10.1128/jb.176.13.4117-4123.1994

Cited by 39 publications

(47 citation statements)

References 42 publications

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“…This synergism means c-type cytochromes are processed under a subtle balance of thiol-disulphide interconversion to become holo proteins, probably sequentially undergoing oxidation and then reduction, rather than being protected from the oxidising power of the DsbA/B system as has been suggested [29]. Such thiol-disulphide redox balancing mechanisms in the periplasm could also in part explain the identification of periplasmic and thioredoxin-like proteins that are required for c-type cytochrome biogenesis in other bacteria [30,31]. It is notable that evidence in favour of CcmG, an example of such a thioredoxin-type protein, acting as a peri-plasmic disulphide reductase in P. denitrificans has recently been obtained (M.D.…”

Section: Discussionmentioning

confidence: 99%

Mutants of Escherichia coli lacking disulphide oxdoreductases DsbA and DsbB cannot synthesise an exogenous monohaem c‐type cytochrome except in the presence of disulphide compounds

Sambongi

Ferguson

1996

FEBS Letters

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Absence through mutation of two proteins involved in periplasmic disulphide bond formation, DsbA and DsbB, results in failure of anaerobically grown Escherichia coli to synthesise the holo forms of either its endogenous c-type cytochrome nitrite reductase or exogenous cytochrome c550 from Paracoccus denitrificans. The synthesis of both cytochromes can be restored to the mutants by inclusion in the growth media of compounds containing disulphide bonds, e.g., the oxidised form of glutathione. The results suggest that the attachment of haem to the CXXCH motif of a periplasmic c-type cytochrome may be preceeded by the formation of one or more intra-or intermolecular disulphide bonds involving the cysteine residues of this motif.

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Section: Discussionmentioning

confidence: 99%

Mutants of Escherichia coli lacking disulphide oxdoreductases DsbA and DsbB cannot synthesise an exogenous monohaem c‐type cytochrome except in the presence of disulphide compounds

Sambongi

Ferguson

1996

FEBS Letters

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“…Our present work does not show whether the DipZ is a direct reductant for apo-cytochromes c. It is possible that small reductants such as L-cysteine directly interact with apo-cytochromes c. Also such a reducing potential transfer system to apo-cytochromes c may be mediated by the periplasmic HelX-like, or other, thioredoxin-type protein, whose mutation results in the deficiency of c-type cytochrome biogenesis in Rhodobacter capsulatus [16] and Rhizobium leguminosarum [ 17]. HelX-like genes are found in E. coli at aeg-46.5 [18] and in Bradyrhizobium japonicum [19] but it is unclear whether such HelX-like proteins function as a reductant or an oxidant in these organisms.…”

Section: Discussionmentioning

confidence: 99%

Specific thiol compounds complement deficiency in c‐type cytochrome biogenesis in Escherichia coli carrying a mutation in a membrane‐bound disulphide isomerase‐like protein

Sambongi

Ferguson

1994

FEBS Letters

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Escherichia coli JCB606 carries a mutation in the dipZ gene, known to code for a disulphide isomerase-like protein, with the consequence that holo forms of neither exogenous nor endogenous c-type cytochromes are synthesised. This failure has been overcome by adding compounds containing thiol groups to the growth medium. Only L-cysteine and 2-mercaptoethane sulphonic acid were effective, suggesting a (stereo)specific binding site that could be occupied by these compounds in the absence of the catalytic domain of DipZ.

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“…Thioredoxin also has a general 'non specific' disulphide reductase function, reducing any accessible disulphide bridge on a given protein (Holmgren, 1989). This type of function might be required for assembly processes such as the heme attachment to apocytochrome c (Vargas et al, 1994). A Saccharoniyces cerevisiae strain has been disrupted in both thioredoxin genes by Muller (1991).…”

Section: Non-photosynthetic Organismsmentioning

confidence: 99%

Thioredoxins: structure and function in plant cells

1997

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SUMMARY Thioredoxins are ubiquitous small‐molecular‐weight proteins (typically 100–120 amino‐acid residues) containing an extremely reactive disulphide bridge with a highly conserved sequence ‐Cys‐Gly(Ala/Pro)‐Pro‐Cys‐. In bacteria and animal cells, thioredoxins participate in multiple reactions which require reduction of disulphide bonds on selected target proteins/ enzymes. There is now ample biochemical evidence that thioredoxins exert very specific functions in plants, the best documented being the redox regulation of chloroplast enzymes. Another area in which thioredoxins are believed to play a prominent role is in reserve protein mobilization during the process of germination. It has been discovered that thioredoxins constitute a large multigene family in plants with different‐subcellular localizations, a unique feature in living cells so far. Evolutionary studies based on these molecules will be discussed, as well as the available biochemical and genetic evidence related to their functions in plant cells. Eukaryotic photosynthetic plant cells are also unique in that they possess two different reducing systems, one extrachloroplastic dependent on NADPH as an electron donor, and the other one chloroplastic, dependent on photoreduced ferredoxin. This review will examine in detail the latest progresses in the area of thioredoxin structural biology in plants, this protein being an excellent model for this purpose. The structural features of the reducing enzymes ferredoxin thioredoxin reductase and NADPH thioredoxin reductase will also be described. The properties of the target enzymes known so far in plants will be detailed with special emphasis on the structural features which make them redox regulatory. Based on sequence analysis, evidence will be presented that redox regulation of enzymes of the biosynthetic pathways first appeared in cyanobacteria possibly as a way to cope with the oxidants produced by oxygenic photosynthesis. It became more elaborate in the chloroplasts of higher plants where a co‐ordinated functioning of the chloroplastic and extra chloroplastic metabolisms is required.

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Identification of a gene encoding a thioredoxin-like product necessary for cytochrome c biosynthesis and symbiotic nitrogen fixation in Rhizobium leguminosarum

Cited by 39 publications

References 42 publications

Mutants of Escherichia coli lacking disulphide oxdoreductases DsbA and DsbB cannot synthesise an exogenous monohaem c‐type cytochrome except in the presence of disulphide compounds

Mutants of Escherichia coli lacking disulphide oxdoreductases DsbA and DsbB cannot synthesise an exogenous monohaem c‐type cytochrome except in the presence of disulphide compounds

Specific thiol compounds complement deficiency in c‐type cytochrome biogenesis in Escherichia coli carrying a mutation in a membrane‐bound disulphide isomerase‐like protein

Thioredoxins: structure and function in plant cells

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