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In vivo oxidative protein folding can be facilitated by oxidation–reduction cycling
Author(s) -
Shouldice Stephen R.,
Cho SeungHyun,
Boyd Dana,
Heras Begoña,
Eser Markus,
Beckwith Jon,
Riggs Paul,
Martin Jennifer L.,
Berkmen Mehmet
Publication year - 2010
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2009.06952.x
Subject(s) - periplasmic space , dsba , biochemistry , protein disulfide isomerase , protein folding , thioredoxin , biology , isomerase , ferredoxin , reductase , folding (dsp implementation) , chaperone (clinical) , enzyme , escherichia coli , medicine , pathology , electrical engineering , engineering , gene
Summary Current dogma dictates that bacterial proteins with misoxidized disulfide bonds are shuffled into correctly oxidized states by DsbC. There are two proposed mechanisms for DsbC activity. The first involves a DsbC‐only model of substrate disulfide rearrangement. The second invokes cycles of reduction and oxidation of substrate disulfide bonds by DsbC and DsbA respectively. Here, we addressed whether the second mechanism is important in vivo by identifying whether a periplasmic reductase could complement DsbC. We screened for naturally occurring periplasmic reductases in Bacteroides fragilis , a bacterium chosen because we predicted it encodes reductases and has a reducing periplasm. We found that the B. fragilis periplasmic protein TrxP has a thioredoxin fold with an extended N‐terminal region; that it is a very active reductase but a poor isomerase; and that it fully complements dsbC . These results provide direct in vivo evidence that correctly folded protein is achievable via cycles of oxidation and reduction.