Structural Comparison of Cuticle and Interstitial Collagens from Annelids Living in Shallow Sea-water and at Deep-sea Hydrothermal Vents
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Two types of annelid collagens of different sizes were purified, one from acetic acid extracts of the cuticle (length 2.5 μm) and the other, after pepsin digestion, from interstitial spaces of the body wall (0.3 μm). They were obtained fromAlvinella pompejana, Alvinella caudataandParalvinella grassleicollected at 2600 m depth around anoxic hydrothermal vents and fromArenicola marinaandNereis diversicolorliving in shallow sea-water habitats. The length of the corresponding collagens from different species and their amino acid compositions including the hydroxylation of proline were remarkably similar. The melting point of the triple helix, however, differed between theAlvinellaspecies (
45°C),Paralvinella(35°C) and the shallow sea-water annelids (28°C), indicating adaption to habitats with different temperatures. The cuticle collagens of the annelids possess a globular domain, which is apparently involved in oligomer formation, and show similar fragment pattern. Almost identical cross-striation patterns of segment-long-spacing segments of the interstitial collagens indicated sequence similarity, which was confirmed by partial Edman degradation of α-chains. These data showed almost complete identity between the twoAlvinellaspecies and a lower sequence identity withParalvinella(95 % ),Arenicola(67 to 72 % ) and the vent vestimentiferanRiftia pachyptila(64 to 71 % ). The data suggest a close evolutionary relationship between these worms, despite a clear separtion of habitat preference and thermal stability of the collagens.
45°C),Paralvinella(35°C) and the shallow sea-water annelids (28°C), indicating adaption to habitats with different temperatures. The cuticle collagens of the annelids possess a globular domain, which is apparently involved in oligomer formation, and show similar fragment pattern. Almost identical cross-striation patterns of segment-long-spacing segments of the interstitial collagens indicated sequence similarity, which was confirmed by partial Edman degradation of α-chains. These data showed almost complete identity between the twoAlvinellaspecies and a lower sequence identity withParalvinella(95 % ),Arenicola(67 to 72 % ) and the vent vestimentiferanRiftia pachyptila(64 to 71 % ). The data suggest a close evolutionary relationship between these worms, despite a clear separtion of habitat preference and thermal stability of the collagens.