Intramolecular Chaperone of Endosialidase

Several trimeric p-structures similarly require C-terminal trimerization domains (for an overview see [136]). In all cases these domains prevent nonstoichiometric aggregation of the hydrophobic protein cores. In endosialidases the sialidase domain folds independently in the three subunits while the stalk domain is composed of an intertwined triple p-helix which requires a complex folding procedure [105,136]. Recently, a crystal structure has been solved which comprises part of the stalk domain and the CTD of endoNF. The release of the CTD in this construct has been prevented by introducing the mutation S911A into the endoNF-stalk 

Proteolytic maturation is a common theme among phage proteins involving either phage-derived proteases or autocatalytic processes [32,138-141]. In contrast to pro-enzymes like mammalian digestive serine proteases, the function of 

In total, the CTD is released after finishing its job to kinetically stabilize the trimeric complex and to allow proper binding to polysialic acid, which is an important prerequisite for processive degradation of polysialic acid. 

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