title: Structural findings and molecular modeling approach of a TFPI-like inhibitor.
abstract: Specific blood coagulation inhibitors from hematophagous organisms, with different structures and novel mechanism of action, have been described and they represent promising agents for the treatment of a variety of human diseases related to coagulation and cancer. In our lab, the salivary glands transcriptome of the adult Amblyomma cajennense tick was previously characterized by expressed sequence tags (EST). A transcript that codes for a tissue factor pathway inhibitor (TFPI)-like protein with unique structure was found, and the recombinant form of this protein was named Amblyomin-X. This protein was able to inhibit the factor Xa amidolytic activity and the activation of factor X by the extrinsic tenase complex (FVIIa/TF). Herein, it was performed functional and structural evaluation of Amblyomin-X. The CD assay and molecular dynamics simulations revealed that Amblyomin-X is structurally stable and the naturally unfolded regions as well as the presence of three disulfide bridges in its Kunitz-type domain seem to sustain its inhibitory activity. Regarding the electrostatic potential mapping on the Kunitz-type region, the pattern of charged residues was not quite the same in comparison to human TFPI-1 and TFPI-2, pointing out there might be distinct functional and structural features, which are going to be experimentally exploited.
authors: Kerly Fernanda Mesquita
authors: KF
authors: Pasqualoto
authors: Andrea
authors: A
authors: Balan
authors: Sandra Alves
authors: SA
authors: Barreto
authors: Simone Michaela
authors: SM
authors: Simons
authors: Laboratorio de Bioquimica e Biofisica, Instituto Butantan, Avenida Vital Brasil, 1500, Sao Paulo, SP 05503-900, Brasil. amchudzinski@butantan.gov.br.
authors: Ana Marisa
authors: AM
authors: Chudzinski-Tavassi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D060829:Arthropod Proteins; D002942:Circular Dichroism; D065427:Factor Xa Inhibitors; D006023:Glycoproteins / Q000737:chemistry; D006801:Humans; D008074:Lipoproteins / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012471:Salivary Proteins and Peptides / Q000737:chemistry*; D016415:Sequence Alignment; D013987:Ticks / Q000737:chemistry*
chemical_list: C559369:Amblyomin-X protein, Amblyomma cajennense; D060829:Arthropod Proteins; D065427:Factor Xa Inhibitors; D006023:Glycoproteins; D008074:Lipoproteins; D012471:Salivary Proteins and Peptides; C051928:lipoprotein-associated coagulation inhibitor; C021240:tissue-factor-pathway inhibitor 2