Format

Send to

Choose Destination
See comment in PubMed Commons below
PLoS One. 2012;7(2):e29964. doi: 10.1371/journal.pone.0029964. Epub 2012 Feb 23.

Simukunin from the salivary glands of the black fly Simulium vittatum inhibits enzymes that regulate clotting and inflammatory responses.

Author information

1
Department of Entomology, The University of Georgia, Athens, Georgia, United States of America.

Abstract

BACKGROUND:

Black flies (Diptera: Simuliidae) feed on blood, and are important vectors of Onchocerca volvulus, the etiolytic agent of River Blindness. Blood feeding depends on pharmacological properties of saliva, including anticoagulation, but the molecules responsible for this activity have not been well characterized.

METHODOLOGY/PRINCIPAL FINDINGS:

Two Kunitz family proteins, SV-66 and SV-170, were identified in the sialome of the black fly Simulium vittatum. As Kunitz proteins are inhibitors of serine proteases, we hypothesized that SV-66 and/or -170 were involved in the anticoagulant activity of black fly saliva. Our results indicated that recombinant (r) SV-66 but not rSV-170 inhibited plasma coagulation. Mutational analysis suggested that SV-66 is a canonical BPTI-like inhibitor. Functional assays indicated that rSV66 reduced the activity of ten serine proteases, including several involved in mammalian coagulation. rSV-66 most strongly inhibited the activity of Factor Xa, elastase, and cathepsin G, exhibited lesser inhibitory activity against Factor IXa, Factor XIa, and plasmin, and exhibited no activity against Factor XIIa and thrombin. Surface plasmon resonance studies indicated that rSV-66 bound with highest affinity to elastase (K(D) = 0.4 nM) and to the active site of FXa (K(D) = 3.07 nM). We propose the name "Simukunin" for this novel protein.

CONCLUSIONS:

We conclude that Simukunin preferentially inhibits Factor Xa. The inhibition of elastase and cathepsin G further suggests this protein may modulate inflammation, which could potentially affect pathogen transmission.

PMID:
22383955
PMCID:
PMC3285612
DOI:
10.1371/journal.pone.0029964
[Indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Public Library of Science Icon for PubMed Central
    Loading ...
    Support Center