Evidence of a bactericidal permeability increasing protein in an invertebrate, the Crassostrea gigas Cg -BPI

doi:10.1073/pnas.0702281104

Evidence of a bactericidal permeability increasing protein in an invertebrate, the Crassostrea gigas Cg-BPI

*Ifremer, Centre National de la Recherche Scientifique, Université Montpellier 2, Unité Mixte de Recherche 5119, Ecosystèmes Lagunaires, Place E. Bataillon, CC80, 34095 Montpellier Cedex 5, France;
^†Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5236, Centre d'Études d'Agents Pathogènes et Biotechnologie pour la Santé, Institut de Biologie, 34965 Montpellier, France;
^§Ecologie Numérique et Ecotoxicologie, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq, France;
^¶Children's Hospital Boston and Harvard Medical School, Boston, MA 02115; and
^‖Atheris Laboratories, CP314, 1233 Bernex-Geneva, Switzerland

Edited by Jerrold P. Weiss, University of Iowa, Coralville, IA, and accepted by the Editorial Board September 20, 2007 (received for review March 14, 2007)

Abstract

A cDNA sequence with homologies to members of the LPS-binding protein and bactericidal/permeability-increasing protein (BPI) family was identified in the oyster Crassostrea gigas. The recombinant protein was found to bind LPS, to display bactericidal activity against Escherichia coli, and to increase the permeability of the bacterial cytoplasmic membrane. This indicated that it is a BPI rather than an LPS-binding protein. By in situ hybridization, the expression of the C. gigas BPI (Cg-bpi) was found to be induced in hemocytes after oyster bacterial challenge and to be constitutive in various epithelia of unchallenged oysters. Thus, Cg-bpi transcripts were detected in the epithelial cells of tissues/organs in contact with the external environment (mantle, gills, digestive tract, digestive gland diverticula, and gonad follicles). Therefore, Cg-BPI, whose expression profile and biological properties are reminiscent of mammalian BPIs, may provide a first line of defense against potential bacterial invasion. To our knowledge, this is the first characterization of a BPI in an invertebrate.

Footnotes

**To whom correspondence should be addressed. E-mail: evelyne.bachere{at}ifremer.fr
Author contributions: Y.G., D.D.-G., and E.B. designed research; M.G., Y.G., D.D.-G., B.R., J.F., M.P., F.R., J.-M.E., F.V., L.S., and P.B. performed research; M.P., F.R., and F.V. contributed new reagents/analytic tools; M.G., D.D.-G., B.R., M.P., F.R., J.-M.E., F.V., O.L., P.B., and E.B. analyzed data; and M.G., Y.G., D.D.-G., P.B., and E.B. wrote the paper.
↵ ^‡Present address: Institut National de la Recherche Agronomique, Université de Montpellier 2, Unité Mixte de Recherche 1133, Ecologie Microbienne des Insectes et Interactions Hôte-Pathogène, Place E. Bataillon, CC54, 34095 Montpellier Cedex 5, France.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission. J.P.W. is a guest editor invited by the Editorial Board.
Abbreviations:

LBP,

LPS-binding protein;

BPI,

bactericidal/permeability-increasing protein;

ONPG,

O-nitrophenyl-β-d-galactopyranoside;

hBPI,

human BPI;

rhBPI,

recombinant hBPI;

hLBP,

human LBP;

AU,

arbitrary unit.