Crystal Structure of Thrombin in Complex with S-Variegin: Insights of a Novel Mechanism of Inhibition and Design of Tunable Thrombin Inhibitors

Koh, Cho Yeow; Kumar, Srinivasan Dinesh; Kazimírová, Mária; Nuttall, Patricia A.; Radhakrishnan, Uvaraj P.; Kim, Seong-Cheol; Jagadeeswaran, Pudur; Imamura, Takayuki; Mizuguchi, Jin; Iwanaga, Sadaaki; Swaminathan, Kunchithapadam; Kini, R. Manjunatha

doi:10.1371/journal.pone.0026367

Cited by 41 publications

(55 citation statements)

References 59 publications

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“…Investigations have included studies on anti‐tumoral effects (Chudzinski‐Tavassi et al ., 2010; Abreu et al ., 2014; Sousa et al ., 2015), applications against inflammatory diseases like myasthenia gravis (Hepburn et al ., 2007), new anticoagulants (Koh et al ., 2011) and the treatment of asthma (Horka et al ., 2012). …”

Section: Tick Saliva As a Source Of Toxins Tick‐borne Pathogens And mentioning

confidence: 99%

Tick attachment cement – reviewing the mysteries of a biological skin plug system

et al. 2017

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The majority of ticks in the family Ixodidae secrete a substance anchoring their mouthparts to the host skin. This substance is termed cement. It has adhesive properties and seals the lesion during feeding. The particular chemical composition and the curing process of the cement are unclear. This review summarizes the literature, starting with a historical overview, briefly introducing the different hypotheses on the origin of the adhesive and how the tick salivary glands have been identified as its source. Details on the sequence of cement deposition, the curing process and detachment are provided. Other possible functions of the cement, such as protection from the host immune system and antimicrobial properties, are presented. Histochemical and ultrastructural data of the intracellular granules in the salivary gland cells, as well as the secreted cement, suggest that proteins constitute the main material, with biochemical data revealing glycine to be the dominant amino acid. Applied methods and their restrictions are discussed. Tick cement is compared with adhesives of other animals such as barnacles, mussels and sea urchins. Finally, we address the potential of tick cement for the field of biomaterial research and in particular for medical applications in future.

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Section: Tick Saliva As a Source Of Toxins Tick‐borne Pathogens And mentioning

confidence: 99%

Tick attachment cement – reviewing the mysteries of a biological skin plug system

et al. 2017

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“…Another distinctive feature of madanins is the absence of cysteine residues in their amino acid sequence, placing them in the restricted group of cysteine-less thrombin inhibitors, together with thrombostasin (from the horn fly Haematobia irritans [10]; MEROPS family I64), tsetse thrombin inhibitor (from Glossina morsitans morsitans [11]; MEROPS family I76), chimadanin (from H. longicornis [12]; MEROPS family I72), anophelin (from Anopheles mosquitoes [13]; MEROPS family I77) and variegin (from the tropical bont tick Amblyomma variegatum [14]; MEROPS family I74). The molecular mechanism of action of two of these atypical serine proteinase inhibitors, anophelin and variegin, has been unveiled by the crystallographic three-dimensional structures of their complexes with thrombin [15], [16]. Whereas anophelin and variegin bind tightly to thrombin, madanins were shown to bind to thrombin with low affinity [7].…”

Section: Introductionmentioning

confidence: 99%

The Tick-Derived Anticoagulant Madanin Is Processed by Thrombin and Factor Xa

2013

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The cysteine-less peptidic anticoagulants madanin-1 and madanin-2 from the bush tick Haemaphysalis longicornis are the founding members of the MEROPS inhibitor family I53. It has been previously suggested that madanins exert their functional activity by competing with physiological substrates for binding to the positively charged exosite I (fibrinogen-binding exosite) of α-thrombin. We hereby demonstrate that competitive inhibition of α-thrombin by madanin-1 or madanin-2 involves binding to the enzyme's active site. Moreover, the blood coagulation factors IIa and Xa are shown to hydrolyze both inhibitors at different, although partially overlapping cleavage sites. Finally, the three-dimensional structure of the complex formed between human α-thrombin and a proteolytic fragment of madanin-1, determined by X-ray crystallography, elucidates the molecular details of madanin-1 recognition and processing by the proteinase. Taken together, the current findings establish the mechanism of action of madanins, natural anticoagulants that behave as cleavable competitive inhibitors of thrombin.

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“…Thrombin is an atypical (chymo)trypsin-like enzyme, with stringent specificity arising from its narrow active site cleft and secondary positively charged recognition surfaces (exosites) (12). Exosites are not only essential for substrate and cofactor binding (13)(14)(15)(16)(17)(18) but also, are targeted by many natural anticoagulants (19)(20)(21)(22)(23)(24)(25). Thorough kinetic analyses revealed that anophelin is a dual inhibitor that binds both the exosite I and the active site of the target proteinase (6,7).…”

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confidence: 99%

Unique thrombin inhibition mechanism by anophelin, an anticoagulant from the malaria vector

Figueiredo

Sanctis

Gutiérrez-Gallego

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Anopheles mosquitoes are vectors of malaria, a potentially fatal blood disease affecting half a billion humans worldwide. These blood-feeding insects include in their antihemostatic arsenal a potent thrombin inhibitor, the flexible and cysteine-less anophelin.Here, we present a thorough structure-and-function analysis of thrombin inhibition by anophelin, including the 2.3-Å crystal structure of the human thrombin·anophelin complex. Anophelin residues 32-61 are well-defined by electron density, completely occupying the long cleft between the active site and exosite I. However, in striking contrast to substrates, the D50-R53 anophelin tetrapeptide occupies the active site cleft of the enzyme, whereas the upstream residues A35-P45 shield the regulatory exosite I, defining a unique reverse-binding mode of an inhibitor to the target proteinase. The extensive interactions established, the disruption of thrombin's active site charge-relay system, and the insertion of residue R53 into the proteinase S 1 pocket in an orientation opposed to productive substrates explain anophelin's remarkable specificity and resistance to proteolysis by thrombin. Complementary biophysical and functional characterization of point mutants and truncated versions of anophelin unambiguously establish the molecular mechanism of action of this family of serine proteinase inhibitors (I77). These findings have implications for the design of novel antithrombotics.coagulation inhibitor | macromolecular recognition | protease | X-ray structure | catalytic triad

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Crystal Structure of Thrombin in Complex with S-Variegin: Insights of a Novel Mechanism of Inhibition and Design of Tunable Thrombin Inhibitors

Cited by 41 publications

References 59 publications

Tick attachment cement – reviewing the mysteries of a biological skin plug system

Tick attachment cement – reviewing the mysteries of a biological skin plug system

The Tick-Derived Anticoagulant Madanin Is Processed by Thrombin and Factor Xa

Unique thrombin inhibition mechanism by anophelin, an anticoagulant from the malaria vector

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