Topography of a 2.0 Å structure of α<sub>1</sub>‐antitrypsin reveals targets for rational drug design to prevent conformational disease

Elliott, Peter R.; Pei, X.Y.; Dafforn, Timothy R.; Lomas, David A.

doi:10.1110/ps.9.7.1274

Cited by 179 publications

(201 citation statements)

References 51 publications

Supporting

Mentioning

195

Contrasting

Order By: Relevance

“…2) in which the RCL is completely exposed. For example, the main chain trace within this region of CBG is identical to those of uncleaved human AAT (32)(33)(34), thermopin (35), and some noninhibitory serpins such as ovalbumin (36) and maspin (37). Interestingly, the conformation of the RCL observed in CBG also resembles that of other ligand-bound serpins, such as the complex of antithrombin with a pentasaccharide ligand (21, 38) (Fig.…”

Section: Resultsmentioning

confidence: 79%

Corticosteroid-binding Globulin, a Structural Basis for Steroid Transport and Proteinase-triggered Release

Klieber

Underhill

Hammond

et al. 2007

Journal of Biological Chemistry

113

121

View full text Add to dashboard Cite

Corticosteroid-binding globulin (CBG) is a serine proteinase inhibitor (serpin) family member that transports glucocorticoids in blood and regulates their access to target cells. The 1.9 Å crystal structure of rat CBG shows that its steroid-binding site resembles the thyroxin-binding site in the related serpin, thyroxin-binding globulin, and mutagenesis studies have confirmed the contributions of key residues that constitute the steroid-binding pocket. Unlike thyroxin-bound thyroxin-binding globulin, the cortisol-bound CBG displays an "active" serpin conformation with the proteinase-sensitive, reactive center loop (RCL) fully expelled from the regulatory ␤-sheet A. Moreover, the CBG structure allows us to predict that complete insertion of the proteolytically cleaved RCL into the serpin fold occurs in concert with a displacement and unwinding of helix D that would disrupt the steroid-binding site. This allosteric coupling between RCL positioning and occupancy of the CBG steroidbinding site, which resembles the ligand (glycosamino-glycan)-dependent activation of the thrombin inhibitory serpins heparin cofactor II and anti-thrombin RCLs, ensures both optimal recognition of CBG by target proteinases and efficient release of steroid to sites of action.Glucocorticoid hormones (cortisol and corticosterone) and progesterone are transported in the blood by a glycoprotein known as corticosteroid-binding globulin (CBG) 3 or transcortin (1). Plasma CBG also binds several synthetic glucocorticoids, such as prednisolone (2), and influences the half-life, distribution, and efficacy of these drugs in the same way as for natural steroids (3). The steroid binding characteristics of CBG from many species have been documented (1), and a benchmark set of CBG steroid binding characteristics has be used to develop three-dimensional quantitative structure activity relationship (3D-QSAR) computational methods (4, 5) aimed at predicting the binding affinities of ligands to target proteins. Although residues within CBG sequences critical for steroid binding have been identified through studies of naturally occurring variants (6 -10), photo-affinity labeling (11), and mutagenesis (12), a precise picture of its structure and steroidbinding site has been lacking.The primary structure of CBG defines it as a clade A member of the serine proteinase inhibitor (serpin) superfamily, together with the related transport protein for thyroxin, thyroxin-binding globulin (TBG), and the prototypical serpin members ␣1-antitrypsin (AAT) and ␣1-antichymotrypsin (ACT), among others (13,14). A hallmark of serpin structures is that they undergo conformational rearrangements as part of their biological function. The conformations they adopt are highly dependent on whether a surface-exposed loop, known as the reactive center loop (RCL) or "proteinase bait" domain, is intact. Cleavage of the RCL segment by proteinases usually causes a typical stressed to relaxed (S 3 R) transition in structure (15). This involves insertion of the entire N-terminal segment of t...

show abstract

Section: Resultsmentioning

confidence: 79%

Corticosteroid-binding Globulin, a Structural Basis for Steroid Transport and Proteinase-triggered Release

Klieber

Underhill

Hammond

et al. 2007

Journal of Biological Chemistry

113

121

View full text Add to dashboard Cite

show abstract

“…The liver tissue specimens were fixed in formalin and embedded in paraffin. Serial sections were stained with either hematoxylin or 2 The reactive center loop that binds to neutrophil elastase is shown in red, and ␤-sheet A is illustrated in green. The position of the Z mutation (Glu342Lys) is shown (arrow).…”

Section: Methodsmentioning

confidence: 99%

“…1 The average concentration of ␣ 1 -antitrypsin in plasma in individuals with 2 normal M alleles (Pi M) is approximately 1.3 mg/mL, with a half-life of 3 to 5 days. Biochemical and crystallographic studies have revealed that the structure of ␣ 1 -antitrypsin is based on three ␤-sheets (A-C) and an exposed mobile reactive loop that presents the P1-P1Ј methionine-serine residues as a pseudosubstrate for the target proteinase 2 (Fig. 1).…”

mentioning

confidence: 99%

Differential detection of PAS-positive inclusions formed by the Z, Siiyama, and Mmalton variants of α1-antitrypsin

et al. 2004

Self Cite

View full text Add to dashboard Cite

“…Serpins are serine protease inhibitors, about 400 amino acid residues long (17-20), with an exposed reactive center loop near their carboxyl terminus (21,22). The P1 residue located in this loop determines the primary specificity of inhibition.…”

mentioning

confidence: 99%

Manduca sexta Serpin-4 and Serpin-5 Inhibit the Prophenol Oxidase Activation Pathway

Tong

Kanost

2005

Journal of Biological Chemistry

108

View full text Add to dashboard Cite

Infection stimulates the innate immune responses of insects, including activation of prophenol oxidase (pro-PO) in plasma as the last step of a serine protease cascade. To investigate the roles of protease inhibitors in regulating this pathway, we cloned cDNAs for two new serpins (serpin-4 and serpin-5) from the tobacco hornworm, Manduca sexta. Serpin-4 and serpin-5 mRNAs are constitutively expressed at a low level in larval hemocytes and fat body and increased dramatically upon bacterial challenge. These serpins are present in larval plasma at ϳ3 (serpin-4) and ϳ1 g/ml (serpin-5) and increased 3-8-fold by 24 h after injection of bacteria or fungi. Recombinant serpin-4 and serpin-5 decreased pro-PO activation when added to plasma, but they did not directly inhibit the pro-PO-activating proteases. Instead, they apparently regulate the pathway by inhibiting one or more target proteases upstream of the pro-PO-activating proteases.Prophenol oxidase (pro- PO) 1 activation is an innate immune response in arthropods. Upon injury or infection, a pro-PO zymogen in plasma is activated by a specific protease. Phenol oxidase (PO) hydroxylates monophenols to o-diphenols and then oxidizes o-diphenols to quinones, which can polymerize to form melanin at the injury site or around invading organisms (1, 2). Quinones may also be involved in the production of cytotoxic molecules such as superoxides and hydroxyl radicals that could help kill the invading organisms (1, 3).A serine protease cascade functions in pro-PO activation (2, 4, 5). The final protease in the pathway, pro-PO-activating protease (PAP) (also called pro-PO-activating enzyme or factor) has been identified from several insects, including the tobacco hornworm, Manduca sexta (6 -8), the silkworm, Bombyx mori (9), a beetle, Holotrichia diomphalia (10, 11), and from a crustacean, the crayfish Pacifastacus leniusculus (12). These PAPs contain one or two clip domains at their amino terminus and a serine protease domain at their carboxyl terminus (13). PAPs are synthesized as zymogens, which are activated by a specific proteolytic cleavage between the clip domain and the protease domain. However, protease(s) that activate PAPs have not yet been characterized.Serpins present in plasma regulate the pro-PO activation pathway (4,5,(13)(14)(15)(16). Serpins are serine protease inhibitors, about 400 amino acid residues long (17-20), with an exposed reactive center loop near their carboxyl terminus (21,22). The P1 residue located in this loop determines the primary specificity of inhibition. Four serpins from M. sexta have been characterized previously. The serpin-1 gene encodes 12 variants with different inhibitory selectivity, due to alternative splicing of exons that encode the reactive center loop (23-25). Serpin-1 mRNA is constitutively expressed in the larval fat body and at a lower level in hemocytes (26). One of the reactive site variants, serpin-1J, inhibits pro-PO activation in plasma by inhibiting PAPs (8, 25). Serpin-2 is an intracellular protein (27), expressed in ...

show abstract

Topography of a 2.0 Å structure of α₁‐antitrypsin reveals targets for rational drug design to prevent conformational disease

Cited by 179 publications

References 51 publications

Corticosteroid-binding Globulin, a Structural Basis for Steroid Transport and Proteinase-triggered Release

Corticosteroid-binding Globulin, a Structural Basis for Steroid Transport and Proteinase-triggered Release

Differential detection of PAS-positive inclusions formed by the Z, Siiyama, and Mmalton variants of α1-antitrypsin

Manduca sexta Serpin-4 and Serpin-5 Inhibit the Prophenol Oxidase Activation Pathway

Contact Info

Product

Resources

About

Topography of a 2.0 Å structure of α1‐antitrypsin reveals targets for rational drug design to prevent conformational disease

Cited by 179 publications

References 51 publications

Corticosteroid-binding Globulin, a Structural Basis for Steroid Transport and Proteinase-triggered Release

Corticosteroid-binding Globulin, a Structural Basis for Steroid Transport and Proteinase-triggered Release

Differential detection of PAS-positive inclusions formed by the Z, Siiyama, and Mmalton variants of α1-antitrypsin

Manduca sexta Serpin-4 and Serpin-5 Inhibit the Prophenol Oxidase Activation Pathway

Contact Info

Product

Resources

About

Topography of a 2.0 Å structure of α₁‐antitrypsin reveals targets for rational drug design to prevent conformational disease