Solution structures of Mycobacterium tuberculosis thioredoxin C and models of intact thioredoxin system suggest new approaches to inhibitor and drug design

Abstract

Here we report the NMR solution structures of Mycobacterium tuberculosis (M. tuberculosis) thioredoxin C in both oxidized and reduced states, with discussion of structural changes that occur in going between redox states. The NMR solution structure of the oxidized TrxC corresponds closely to that of the crystal structure, except in the C-terminal region. It appears that crystal packing effects have caused an artifactual shift in the α4 helix in the previously reported crystal structure, compared to the solution structure. Based on these TrxC structures, chemical shift mapping, a previously reported crystal structure of the M. tuberculosis thioredoxin reductase (not bound to a Trx) and structures for intermediates in the E. coli thioredoxin catalytic cycle, we have modeled the complete M. tuberculosis thioredoxin system for the various steps in the catalytic cycle. These structures and models reveal pockets at the TrxR/TrxC interface in various steps in the catalytic cycle, which can be targeted in the design of uncompetitive inhibitors as potential anti-mycobacterial agents, or as chemical genetic probes of function.

AhpC of the mycobacterial antioxidant defense system and its interaction with its reducing partner Thioredoxin-C

“…Inclusion of additional residues that showed increased linewidths in the NMR experiments above for the Mb TrxC- Mb AhpC interactions in the docking, did not produce a better complex model.

Figure 8A model of mycobacterial TrxC-AhpC complex based on the NMR titration experiments. TrxC (PDB ID: 2L4Q) 23 is shown in blue and Mt AhpC C176S (PDB ID: 2BMX) 13 in orange color. ( Inset ) A closer view of the various interactions between mycobacterial TrxC and AhpC in the model complex.

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“…The coordinates of mycobacterial AhpC (PDB ID: 2BMX) 13 and TrxC (PDB ID: 2L4Q) 23 were obtained from the Protein Data Bank. Residues experiencing significant perturbation during titration were used as restrains.…”

rSodC is a potential antigen to diagnose Corynebacterium pseudotuberculosis by enzyme-linked immunoassay

“…Tests with the rDTxR, rTrx, TrxR, rLexA, rNanH, rPknG, and rSpaC proteins showed low sensitivity and/or speci city, and were unable to satisfactorily discriminate samples from infected and noninfected animals. These proteins play important roles in the survival of these microorganisms, and have been evaluated in silico and in vitro to determine the potential of these recombinant constructs as therapeutic targets (Resende et al 2011;Olson et al 2013;Lin et al 2016).…”

Docking into Mycobacterium tuberculosis Thioredoxin Reductase Protein Yields Pyrazolone Lead Molecules for Methicillin-Resistant Staphylococcus aureus

“…TrxR and TrxC were expressed and purified as previously described [23]. In the assay, TrxR used NADPH to oxidize TrxC, which spontaneously reduced DTNB.…”