The proteinaceous cement substance produced by barnacles allows tenacious underwater attachment due to cooperation of four cement proteins.
“Barnacles have the capability for tenacious underwater adhesion to the surfaces by a proteinaceous cement substance. Three major s had been identified in a previous study and this study adds a fourth. It is suggested that each cement protein fulfills a distinct and specific role in underwater adhesion, and that firm barnacle adhesion is achieved cooperatively by these cement proteins. Understanding the specific role of each cement protein will help to provide a better understanding of barnacle settlement and of synthetic mimics, including underwater adhesives.” (Courtesy of the Guild)
“Enzymes and biochemical mechanisms essential to survival are under extreme
selective pressure and are highly conserved through evolutionary time. We
applied this evolutionary concept to barnacle cement polymerization, a process
critical to barnacle fitness that involves aggregation and cross-linking of
proteins. The biochemical mechanisms of cement polymerization remain largely
unknown. We hypothesized that this process is biochemically similar to blood
clotting, a critical physiological response that is also based on aggregation
and cross-linking of proteins. Like key elements of vertebrate and
invertebrate blood clotting, barnacle cement polymerization was shown to
involve proteolytic activation of enzymes and structural precursors,
transglutaminase cross-linking and assembly of fibrous proteins. Proteolytic
activation of structural proteins maximizes the potential for bonding
interactions with other proteins and with the surface. Transglutaminase
cross-linking reinforces cement integrity. Remarkably, epitopes and sequences
homologous to bovine trypsin and human transglutaminase were identified in
barnacle cement with tandem mass spectrometry and/or western blotting. Akin to
blood clotting, the s generated during proteolytic activation
functioned as signal molecules, linking a molecular level event (protein
aggregation) to a behavioral response (barnacle larval settlement). Our
results draw attention to a highly conserved protein polymerization mechanism
and shed light on a long-standing biochemical puzzle. We suggest that barnacle
cement polymerization is a specialized form of wound healing. The
polymerization mechanism common between barnacle cement and blood may be a
theme for many marine animal glues.” (Dickinson et al. 2009:3499)
