8IN3

Eisenia hydrolysis-enhancing protein from Aplysia kurodai

Summary for 8IN3

• Entry DOI: 10.2210/pdb8in3/pdb
• Descriptor: 25 kDa polyphenol-binding protein, GLYCEROL (3 entities in total)
• Functional Keywords: ehep, unknown function
• Biological source: Aplysia kurodai (Kuroda's sea hare)
• Total number of polymer chains: 1
• Total formula weight: 24854.08

Authors

Sun, X.M.,Ye, Y.X.,Kato, K.,Yu, J.,Yao, M. (deposition date: 2023-03-08, release date: 2023-11-15, Last modification date: 2024-10-09)

Primary citation

Sun, X.,Ye, Y.,Sakurai, N.,Wang, H.,Kato, K.,Yu, J.,Yuasa, K.,Tsuji, A.,Yao, M.
Structural basis of EHEP-mediated offense against phlorotannin-induced defense from brown algae to protect aku BGL activity.
Elife, 12:-, 2023

PubMed Abstract: The defensive-offensive associations between algae and herbivores determine marine ecology. Brown algae utilize phlorotannin as their chemical defense against the predator , which uses β-glucosidase (BGL) to digest the laminarin in algae into glucose. Moreover, employs hydrolysis-enhancing protein (EHEP) as an offense to protect BGL activity from phlorotannin inhibition by precipitating phlorotannin. To underpin the molecular mechanism of this digestive-defensive-offensive system, we determined the structures of the apo and tannic acid (TNA, a phlorotannin analog) bound forms of EHEP, as well as the apo BGL. EHEP consisted of three peritrophin-A domains arranged in a triangular shape and bound TNA in the center without significant conformational changes. Structural comparison between EHEP and EHEP-TNA led us to find that EHEP can be resolubilized from phlorotannin precipitation at an alkaline pH, which reflects a requirement in the digestive tract. BGL contained two GH1 domains, only one of which conserved the active site. Combining docking analysis, we propose the mechanisms by which phlorotannin inhibits BGL by occupying the substrate-binding pocket, and EHEP protects BGL against this inhibition by binding with phlorotannin to free the BGL pocket.

PubMed: 37910430
DOI: 10.7554/eLife.88939

Experimental method

X-RAY DIFFRACTION (1.15 Å)