X-ray Structure of a Monomeric Cyclophilin A-Cyclosporin A Crystal Complex at 2·1 Å Resolution

1993 ◽  
Vol 234 (4) ◽  
pp. 1119-1130 ◽  
Author(s):  
Vincent Mikol ◽  
Jörg Kallen ◽  
Gaston Pflügl ◽  
Malcolm D. Walkinshaw
2018 ◽  
Vol 26 ◽  
pp. 204020661881141 ◽  
Author(s):  
Ashwaq A Abdullah ◽  
Rasedee Abdullah ◽  
Zeenathul A Nazariah ◽  
Krishnan N Balakrishnan ◽  
Faez Firdaus J Abdullah ◽  
...  

Background Viruses are obligate parasites that depend on the cellular machinery of the host to regenerate and manufacture their proteins. Most antiviral drugs on the market today target viral proteins. However, the more recent strategies involve targeting the host cell proteins or pathways that mediate viral replication. This new approach would be effective for most viruses while minimizing drug resistance and toxicity. Methods Cytomegalovirus replication, latency, and immune response are mediated by the intermediate early protein 2, the main protein that determines the effectiveness of drugs in cytomegalovirus inhibition. This review explains how intermediate early protein 2 can modify the action of cyclosporin A, an immunosuppressive, and antiviral drug. It also links all the pathways mediated by cyclosporin A, cytomegalovirus replication, and its encoded proteins. Results Intermediate early protein 2 can influence the cellular cyclophilin A pathway, affecting cyclosporin A as a mediator of viral replication or anti-cytomegalovirus drug. Conclusion Cyclosporin A has a dual function in cytomegalovirus pathogenesis. It has the immunosuppressive effect that establishes virus replication through the inhibition of T-cell function. It also has an anti-cytomegalovirus effect mediated by intermediate early protein 2. Both of these functions involve cyclophilin A pathway.


2015 ◽  
Vol 112 (16) ◽  
pp. 5177-5182 ◽  
Author(s):  
Vijay Parashar ◽  
Chaitanya Aggarwal ◽  
Michael J. Federle ◽  
Matthew B. Neiditch

Peptide pheromone cell–cell signaling (quorum sensing) regulates the expression of diverse developmental phenotypes (including virulence) in Firmicutes, which includes common human pathogens, e.g.,Streptococcus pyogenesandStreptococcus pneumoniae. Cytoplasmic transcription factors known as “Rgg proteins” are peptide pheromone receptors ubiquitous in Firmicutes. Here we present X-ray crystal structures of aStreptococcusRgg protein alone and in complex with a tight-binding signaling antagonist, the cyclic undecapeptide cyclosporin A. To our knowledge, these represent the first Rgg protein X-ray crystal structures. Based on the results of extensive structure–function analysis, we reveal the peptide pheromone-binding site and the mechanism by which cyclosporin A inhibits activation of the peptide pheromone receptor. Guided by the Rgg–cyclosporin A complex structure, we predicted that the nonimmunosuppressive cyclosporin A analog valspodar would inhibit Rgg activation. Indeed, we found that, like cyclosporin A, valspodar inhibits peptide pheromone activation of conserved Rgg proteins in medically relevantStreptococcusspecies. Finally, the crystal structures presented here revealed that the Rgg protein DNA-binding domains are covalently linked across their dimerization interface by a disulfide bond formed by a highly conserved cysteine. The DNA-binding domain dimerization interface observed in our structures is essentially identical to the interfaces previously described for other members of the XRE DNA-binding domain family, but the presence of an intermolecular disulfide bond buried in this interface appears to be unique. We hypothesize that this disulfide bond may, under the right conditions, affect Rgg monomer–dimer equilibrium, stabilize Rgg conformation, or serve as a redox-sensitive switch.


2005 ◽  
Vol 288 (1) ◽  
pp. F40-F47 ◽  
Author(s):  
Seiji Watanabe ◽  
Shuichi Tsuruoka ◽  
Soundarapandian Vijayakumar ◽  
Gunter Fischer ◽  
Yixin Zhang ◽  
...  

Cyclosporin A (CsA), a widely used immunosuppressant, causes distal renal tubular acidosis (dRTA). It exerts its immunosuppressive effect by a calcineurin-inhibitory complex with its cytosolic receptor, cyclophilin A. However, CsA also inhibits the peptidyl prolyl cis-trans isomerase (PPIase) activity of cyclophilin A. We studied HCO3− transport and changes in β-intercalated cell pH on luminal Cl− removal in isolated, perfused rabbit cortical collecting tubules (CCDs) before and after exposure to media pH 6.8 for 3 h. Acid incubation causes adaptive changes in β-intercalated cells by extracellular deposition of hensin ( J Clin Invest 109: 89, 2002). Here, CsA prevented this adaptation. The unidirectional HCO3− secretory flux, estimated as the difference between net flux and that after Cl− removal from the lumen, was −6.7 ± 0.2 pmol·min−1·mm−1 and decreased to −1.3 ± 0.2 after acid incubation. CsA in the bath prevented the adaptive decreases in HCO3− secretion and apical Cl−:HCO3− exchange. To determine the mechanism, we incubated CCDs with FK-506, which inhibits calcineurin activity independently of the host cell cyclophilin. FK-506 did not prevent the acid-induced adaptive decrease in unidirectional HCO3− secretion. However, [AD-Ser]8 CsA, a CsA derivative, which does not inhibit calcineurin but inhibits PPIase activity of cyclophilin A, completely blocked the effect of acid incubation on apical Cl−:HCO3− exchange. Acid incubation resulted in prominent “clumpy” staining of extracellular hensin and diminished apical surface of β-intercalated cells [smaller peanut agglutinin (PNA) caps]. CsA and [AD-Ser]8 CsA prevented most hensin staining and the reduction of apical surface; PNA caps were more prominent. We suggest that hensin polymerization around adapting β-intercalated cells requires the PPIase activity of cyclophilins. Thus CsA is able to prevent this adaptation by inhibition of a peptidyl prolyl cis-trans isomerase activity. Such inhibition may cause dRTA during acid loading.


Author(s):  
Harshesh Bhatt ◽  
Dipesh Kumar Trivedi ◽  
Ravi Kant Pal ◽  
Atul Kumar Johri ◽  
Narendra Tuteja ◽  
...  

Nature ◽  
1993 ◽  
Vol 361 (6407) ◽  
pp. 91-94 ◽  
Author(s):  
Gaston Pflügl ◽  
Jörg Kallen ◽  
Tilman Schirmer ◽  
Johan N. Jansonius ◽  
Mauro G. M. Zurini ◽  
...  
Keyword(s):  
X Ray ◽  

1998 ◽  
Vol 283 (2) ◽  
pp. 435-449 ◽  
Author(s):  
Joerg Kallen ◽  
Vincent Mikol ◽  
Paul Taylor ◽  
Malcolm D.Walkinshaw
Keyword(s):  

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