Structural aspects of serpin inhibition

Schulze, Andreas; Huber, Robert; Bode, Wolfram; Engh, Richard A.

doi:10.1016/0014-5793(94)00369-6

Cited by 61 publications

(63 citation statements)

References 54 publications

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“…Its physical properties (2), mechanism (3), and structure (4,5) conform to the general model (6, 7) that has been established for serpins. These inhibitors present a flexible reactive site loop, which is cleaved at a susceptible residue by target proteinase (8,9) to form a highly stable, covalent complex (10,11). As in other serpins (12), the reactive site loop in the cleaved form of ACT is inserted into a preexisting, flexible ␤-sheet (sA) (4), and this cleaved form is stabilized to denaturation relative to the uncleaved native form (2).…”

mentioning

confidence: 99%

Alzheimer's Peptide Aβ1–42 Binds to Two β-Sheets of α1-Antichymotrypsin and Transforms It from Inhibitor to Substrate

Janciauskiene¹,

Rubin²,

Lukacs³

et al. 1998

Journal of Biological Chemistry

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The serpin ␣ 1 -antichymotrypsin is a major component of brain amyloid plaques in Alzheimer's disease. In vitro ␣ 1 -antichymotrypsin interacts with the Alzheimer's amyloid peptide A␤ 1-42 and stimulates both formation and disruption of neurotoxic A␤ 1-42 fibrils in a concentration-dependent manner. We have constructed a new hybrid model of the complex between A␤ 1-42 and ␣ 1 -antichymotrypsin in which both amino and carboxyl sequences of A␤ 1-42 insert into two different ␤-sheets of ␣ 1 -antichymotrypsin. We have tested this model and shown experimentally that full-length and amino-terminal segments of A␤ 1-42 bind to ␣ 1 -antichymotrypsin as predicted. We also show that A␤ 1-42 forms both intraand intermolecular SDS-stable complexes with ␣ 1 -antichymotrypsin and that the binding of A␤ 1-42 to ␣ 1 -antichymotrypsin abolishes the inhibitory activity of the latter and its ability to form stable complex with chymotrypsin. The existence of both inter-as well as intramolecular complexes of A␤ 1-42 explains the nonlinear concentration-dependent effects of ␣ 1 -antichymotrypsin on A␤ 1-42 fibril formation, which we have reinvestigated here over a broad range of A␤ 1-42 :␣ 1 -antichymotrypsin ratios. These data suggest a molecular basis for the distinction between amorphous and fibrillar A␤ 1-42 in vivo. The reciprocal effects of A␤ 1-42 and ␣ 1 -antichymotrypsin could play a role in the etiology of Alzheimer's disease.1 is a serpin serine proteinase inhibitor with specificity for cathepsin and chymotrypsin-like enzymes (1). Its physical properties (2), mechanism (3), and structure (4, 5) conform to the general model (6, 7) that has been established for serpins. These inhibitors present a flexible reactive site loop, which is cleaved at a susceptible residue by target proteinase (8, 9) to form a highly stable, covalent complex (10, 11). As in other serpins (12), the reactive site loop in the cleaved form of ACT is inserted into a preexisting, flexible ␤-sheet (sA) (4), and this cleaved form is stabilized to denaturation relative to the uncleaved native form (2). There is evidence (13, 14) consistent with proposals (10, 11) that insertion of the reactive site loop into sA is a prerequisite for stable proteinase-serpin complex formation. In further support of this, it has been shown that exogenous peptides of restricted sequence can insert into sA of the uncleaved serpin (15-17). These binary peptide⅐serpin complexes are similarly increased in stability to denaturation but have lost inhibitory activity, becoming substrates instead that do not form a stable complex with target proteinase.A possible link between ACT and Alzheimer's disease was established by the observation that ACT occurs in the senile plaques characteristic of this disease (18). Subsequently, it was shown in vitro that ACT can either stimulate formation of the neurotoxic fibrillar form of Alzheimer's peptide A␤ 1-42 (19, 20) or destabilize preformed A␤ 1-40 fibrils (21, 22), depending on the stoichiometry of ACT to A␤. Two models for the binding of A␤...

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confidence: 99%

Alzheimer's Peptide Aβ1–42 Binds to Two β-Sheets of α1-Antichymotrypsin and Transforms It from Inhibitor to Substrate

Janciauskiene¹,

Rubin²,

Lukacs³

et al. 1998

Journal of Biological Chemistry

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“…Fully extracted RCLs are either partially in form of an a-helix (Stein et al, 1990), or partially in the form of a distorted a-helix (Wei et al, 1994). Insertion of the hinge region seems to be a prerequisite for inhibitory activity, as blocking of insertion by various means prevents complex formation with target proteinases (see reviews by Bode and Huber, 1992;Gettins et al, 1993;Potempa et al, 1994;Schulze et al, 1994;Stein and Carrell, 1995).…”

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confidence: 99%

Conformational Changes of the Reactive‐Centre Loop and β‐Strand 5A Accompany Temperature‐Dependent Inhibitor‐Substrate Transition of Plasminogen‐Activator Inhibitor 1

Kjøller

Martensen

Sottrup‐Jensen

et al. 1996

European Journal of Biochemistry

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We have studied conformational changes of type-I plasminogen-activator inhibitor (PAI-1) during a temperature-dependent inhibitor -substrate transition by measuring susceptibility of the molecule to nontarget proteinases. When incubated at 0°C instead of the normally used 37"C, a tenfold decrease in the specific inhibitory activity of active PAI-1 was observed. Accordingly, PAI-I was recovered in a reactivecentre-cleaved form from incubations with urokinase-type plasminogen activator (uPA) and tissue-type plasminogen activator (tPA) at 0"C, but not at 37°C. It thus behaved as a substrate for the target proteinases at the lower temperature. Active PAI-1 was exposed to a variety of non-target proteinases, including elastase, papain, thermolysin, trypsin, and V8 proteinase. It was found that specific peptide bonds in the reactive centre loop (RCL) and strand 5 in @-sheet A (sSA) had a temperature-dependent proteolytic susceptibility, while the P,,-P,, (E332-S333) bond, forming the hinge between s5A and the RCL, showed indistinguishable susceptibility to proteolysis by V8 proteinase at 0" and 37°C. In latent and reactivecentre-cleaved PAI-1, all the bonds were resistant to proteolysis at the higher as well as the lower temperature. An anti-PAI-I monoclonal antibody maintained the inhibitory activity of PAIL1 and prevented reactive centre cleavage at 0 "C, and thus prevented substrate behaviour. Concomitantly, it caused specific changes in proteolytic susceptibility of sSA and the RCL, but it did not affect cleavage of the P,,-PI, bond by V8 proteinase. Our observations suggest that temperature-dependent conformational changes of 8-sheet A and the RCL determine whether the serpin act as an inhibitor or a substrate. Furthermore they suggest that the RCL of PAI-I is fully extracted from 8-sheet A in the inhibitory as well as in the substrate form, favoring a so-called induced conformational state model to explain why inhibitory activity requires partial insertion of the RCL into 8-sheet A.Keywords: conformation ; plasminogen-activator inhibitor; proteolysis ; reactive-centre loop; serpin.The serpin superfamily includes of a large number serine proteinase inhibitors and a variety of proteins with other or unknown functions (see reviews by Huber and Carrell, 1989;Potempa et al., 1994). The molecular mechanism of the inhibitory function of all the serine proteinase inhibitor members of the superfamily is thought to be similar, on the basis of a high percentage of sequence identity and the same over-all fold, as shown by X-ray crystal analysis. A key feature is an approximately 20-amino-acid peptide segment, the reactive-centre loop (RCL) which protrudes from the main body of the molecule (see reviews by Bode and Huber, 1992; Stein and Carrell, 1995).

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“…Based solely on the molecular mass range they occupy, the SDF serine peptidase inhibitors (about 15-32 kDa) would seem to be too small to be members of the serpin superfamily [about 40-100 kDa (Kanost 1990;Schulze et al 1994) with most 40-60 kDa (Carrell and Boswell 1986;Worrall et al 1999;Jiang and Kanost 2000;Gan et al 2001)]. They are, on the other hand, larger than many of the non-serpin serine peptidase inhibitors, which include at least nine families of small 'canonical' or 'standard mechanism' serine peptidase inhibitors (Bode and Huber 1992), hirudins, the nematode smapin family (Zang and Maizels 2001), and others (see, e.g., the review by Kanost 1999).…”

Section: Sdf Serine Peptidase Inhibitorsmentioning

confidence: 99%

Astacin family metallopeptidases and serine peptidase inhibitors in spider digestive fluid

Foradori

Tillinghast

Smith

et al. 2006

Comparative Biochemistry and Physiology Part B: Biochemistry an

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Digestive fluid of the araneid spider Argiope aurantia is known to contain zinc metallopeptidases. Using anion-exchange chromatography, size-exclusion chromatography, sucrose density gradient centrifugation, and gel electrophoresis, we isolated two lower-molecular-mass peptidases, designated p16 and p18. The N-terminal amino acid sequences of p16 (37 residues) and p18 (20 residues) are 85% identical over the first 20 residues and are most similar to the N-terminal sequences of the fully active form of meprin (β subunits) from several vertebrates (47-52% and 50-60% identical, respectively). Meprin is a peptidase in the astacin (M12A) subfamily of the astacin (M12) family. Additionally, a 66-residue internal sequence obtained from p16 aligns with the conserved astacin subfamily domain. Thus, at least some spider digestive peptidases appear related to astacin of decapod crustaceans. However, important differences between spider and crustacean metallopeptidases with regard to isoelectric point and their susceptibility to hemolymph-borne inhibitors are demonstrated. Anomalous behavior of the lower-molecular-mass Argiope peptidases during certain fractionation procedures indicates that these peptidases may take part in reversible associations with each other or with other proteins. A. aurantia digestive fluid also contains inhibitory activity effective against insect digestive peptidases. Here we present evidence for at least thirteen, heat-stable serine peptidase inhibitors ranging in molecular mass from about 15 to 32 kDa.

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Structural aspects of serpin inhibition

Cited by 61 publications

References 54 publications

Alzheimer's Peptide Aβ1–42 Binds to Two β-Sheets of α1-Antichymotrypsin and Transforms It from Inhibitor to Substrate

Alzheimer's Peptide Aβ1–42 Binds to Two β-Sheets of α1-Antichymotrypsin and Transforms It from Inhibitor to Substrate

Conformational Changes of the Reactive‐Centre Loop and β‐Strand 5A Accompany Temperature‐Dependent Inhibitor‐Substrate Transition of Plasminogen‐Activator Inhibitor 1

Astacin family metallopeptidases and serine peptidase inhibitors in spider digestive fluid

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