A fast recoiling silk-like elastomer facilitates nanosecond nematocyst discharge

作者：Beckmann Anna; Xiao Senbo; Mueller Jochen P; Mercadante Davide; Nuechter Timm; Kroeger Niels; Langhojer Florian; Petrich Wolfgang; Holstein Thomas W; Benoit Martin; Graeter Frauke; Oezbek Suat

来源：BMC Biology, 2015, 13(1): 3.

DOI：10.1186/s12915-014-0113-1

• Hydra
• Nematocyst
• Elastomer
• Molecular dynamics
• Single molecule force spectroscopy

Background: The discharge of the Cnidarian stinging organelle, the nematocyst, is one of the fastest processes in biology and involves volume changes of the highly pressurised (150 bar) capsule of up to 50%. Hitherto, the molecular basis for the unusual biomechanical properties of nematocysts has been elusive, as their structure was mainly defined as a stress-resistant collagenous matrix.
Results: Here, we characterise Cnidoin, a novel elastic protein identified as a structural component of Hydra nematocysts. Cnidoin is expressed in nematocytes of all types and immunostainings revealed incorporation into capsule walls and tubules concomitant with minicollagens. Similar to spider silk proteins, to which it is related at sequence level, Cnidoin possesses high elasticity and fast coiling propensity as predicted by molecular dynamics simulations and quantified by force spectroscopy. Recombinant Cnidoin showed a high tendency for spontaneous aggregation to bundles of fibrillar structures.
Conclusions: Cnidoin represents the molecular factor involved in kinetic energy storage and release during the ultra-fast nematocyst discharge. Furthermore, it implies an early evolutionary origin of protein elastomers in basal metazoans.

• 出版日期2015-1-16