Mutable collagenous tissues (MCTs) from echinoderms (e.g., sea stars, sea urchins) possess the remarkable ability to change their mechanical properties rapidly and reversibly thanks to the release of effector molecules regulating the number of cross-links between collagen fibrils. Among these effector molecules, tensilin has been identified as a stiffening factor in sea cucumber MCTs. Since its discovery and description twenty years ago, tensilin orthologs have been identified in a few sea cucumber species but no novel information about its molecular mode of action has been reported. In this study, using a combination of in silico analyses, we identified the tensilin present in the dermis of Holothuria forskali, Hf-(D)Tensilin. Anti-peptide antibodies showed that this protein is localised in the secretory granules of type 2 juxtaligamental-like cells, a MCT specific cell type. We then used the bacterium E. coli to produce recombinantly Hf-(D)Tensilin and confirmed its stiffening effect on pieces of the dermis and its aggregation effect on collagen fibrils extracted from the sea cucumber dermis. To investigate how tensilin can cross-bridge collagen fibrils, truncated recombinant tensilins were also produced and used in combination with various compounds. Results suggest that two types of interactions contribute to the aggregation effect of tensilin on the fibrils: (1) the N-terminal NTR TIMP like domain of the protein interacts strongly with sulfated GAGs attached to the surface of the collagen fibrils, and (2) the C-terminal part of the protein is involved in its dimerisation/oligomerisation through ionic but possibly also cation-π and hydrophobic interactions.

来自棘皮动物（例如海星、海胆）的可变胶原组织 (MCT) 具有快速和可逆地改变其机械性能的显着能力，这要归功于调节胶原原纤维之间交联数量的效应分子的释放。在这些效应分子中，张力蛋白已被确定为海参 MCT 中的硬化因子。自二十年前发现和描述以来，已在一些海参物种中鉴定出张力素直系同源物，但尚未报道有关其分子作用模式的新信息。在这项研究中，我们使用计算机分析的组合，确定了Holothuria forskali真皮中存在的张力蛋白, Hf-(D) Tensilin。抗肽抗体表明，这种蛋白质位于 2 型近韧带样细胞（一种 MCT 特异性细胞类型）的分泌颗粒中。然后我们使用了大肠杆菌重组产生 Hf-(D)Tensilin 并证实其对真皮碎片的硬化作用及其对从海参真皮中提取的胶原纤维的聚集作用。为了研究张力蛋白如何跨过胶原原纤维，还生产了截短的重组张力蛋白并将其与各种化合物结合使用。结果表明，两种类型的相互作用有助于张力蛋白对原纤维的聚集作用：（1）蛋白质的 N 末端 NTR TIMP 样结构域与附着在胶原原纤维表面的硫酸化 GAG 强烈相互作用，以及（2）蛋白质的 C 末端部分通过离子相互作用参与其二聚化/寡聚化，但也可能包括阳离子-π 和疏水相互作用。