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A fast recoiling silk-like elastomer facilitates nanosecond nematocyst discharge.

Beckmann A, Xiao S, Müller JP, Mercadante D, Nüchter T, Kröger N, Langhojer F, Petrich W, Holstein TW, Benoit M, Gräter F, Özbek S - BMC Biol. (2015)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Evolution and Genomics, University of Heidelberg, Centre for Organismal Studies, Im Neuenheimer Feld 329, 69120, Heidelberg, Germany. Anna.beckmann@cos.uni-heidelberg.de.

ABSTRACT

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.

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Related in: MedlinePlus

Western blot detection and self-aggregation of Cnidoin. (A) western blot analysis of Cnidoin in isolated nematocysts, the insoluble fraction of nematocysts (ghosts), whole hydra lysate, and after recombinant expression in bacteria and HEK293 cells. (B) transmission electron micrograph of recombinant Cnidoin forming bundles of fibres. Scale bar is 100 nm. (C) western blot analysis of recombinant Cnidoin induced to form disulphide-linked polymers by glutathione treatment.
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Fig3: Western blot detection and self-aggregation of Cnidoin. (A) western blot analysis of Cnidoin in isolated nematocysts, the insoluble fraction of nematocysts (ghosts), whole hydra lysate, and after recombinant expression in bacteria and HEK293 cells. (B) transmission electron micrograph of recombinant Cnidoin forming bundles of fibres. Scale bar is 100 nm. (C) western blot analysis of recombinant Cnidoin induced to form disulphide-linked polymers by glutathione treatment.

Mentions: In western blot analysis Cnidoin was detected as a single band of about 42 kDa in hydra lysates, isolated nematocyst capsules as well as in nematocyst ghosts (Figure 3A). This is slightly lower than the calculated molecular mass of 51.6 kDa including the putative propeptide, indicating that propeptide cleavage does occur during secretion into the nematocyst vesicle. When expressed recombinantly in HEK293 cells, full-length Cnidoin exhibited a molecular mass of about 53 kDa, which matches the calculated mass of Cnidoin including a C-terminal his-tag (53.1 kDa) (Figure 3A). We conclude that in HEK293 cells propeptide cleavage does not occur resulting in the observed molecular mass difference to the native protein, which accounts for the propeptide fragment. The western blot signal was exclusively detectable under reducing conditions suggesting an incorporation of Cnidoin into the disulphide-linked capsule wall polymer similar to NCol-1 and NOWA [13,26].Figure 3


A fast recoiling silk-like elastomer facilitates nanosecond nematocyst discharge.

Beckmann A, Xiao S, Müller JP, Mercadante D, Nüchter T, Kröger N, Langhojer F, Petrich W, Holstein TW, Benoit M, Gräter F, Özbek S - BMC Biol. (2015)

Western blot detection and self-aggregation of Cnidoin. (A) western blot analysis of Cnidoin in isolated nematocysts, the insoluble fraction of nematocysts (ghosts), whole hydra lysate, and after recombinant expression in bacteria and HEK293 cells. (B) transmission electron micrograph of recombinant Cnidoin forming bundles of fibres. Scale bar is 100 nm. (C) western blot analysis of recombinant Cnidoin induced to form disulphide-linked polymers by glutathione treatment.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4321713&req=5

Fig3: Western blot detection and self-aggregation of Cnidoin. (A) western blot analysis of Cnidoin in isolated nematocysts, the insoluble fraction of nematocysts (ghosts), whole hydra lysate, and after recombinant expression in bacteria and HEK293 cells. (B) transmission electron micrograph of recombinant Cnidoin forming bundles of fibres. Scale bar is 100 nm. (C) western blot analysis of recombinant Cnidoin induced to form disulphide-linked polymers by glutathione treatment.
Mentions: In western blot analysis Cnidoin was detected as a single band of about 42 kDa in hydra lysates, isolated nematocyst capsules as well as in nematocyst ghosts (Figure 3A). This is slightly lower than the calculated molecular mass of 51.6 kDa including the putative propeptide, indicating that propeptide cleavage does occur during secretion into the nematocyst vesicle. When expressed recombinantly in HEK293 cells, full-length Cnidoin exhibited a molecular mass of about 53 kDa, which matches the calculated mass of Cnidoin including a C-terminal his-tag (53.1 kDa) (Figure 3A). We conclude that in HEK293 cells propeptide cleavage does not occur resulting in the observed molecular mass difference to the native protein, which accounts for the propeptide fragment. The western blot signal was exclusively detectable under reducing conditions suggesting an incorporation of Cnidoin into the disulphide-linked capsule wall polymer similar to NCol-1 and NOWA [13,26].Figure 3

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Evolution and Genomics, University of Heidelberg, Centre for Organismal Studies, Im Neuenheimer Feld 329, 69120, Heidelberg, Germany. Anna.beckmann@cos.uni-heidelberg.de.

ABSTRACT

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.

Show MeSH
Related in: MedlinePlus