6E18

Crystal structure of Chlamydomonas reinhardtii HAP2 ectodomain provides structural insights of functional loops in green algae.

Summary for 6E18

• Entry DOI: 10.2210/pdb6e18/pdb
• Descriptor: Hapless 2, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, alpha-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-[alpha-L-fucopyranose-(1-6)]2-acetamido-2-deoxy-beta-D-glucopyranose, ... (6 entities in total)
• Functional Keywords: gamete fusion, membrane binding motif, glycoprotein, cystine ladder, membrane protein
• Biological source: Chlamydomonas reinhardtii
• Total number of polymer chains: 1
• Total formula weight: 63124.24

Authors

Baquero, E.,Legrand, P.,Rey, F.A. (deposition date: 2018-07-09, release date: 2018-11-07, Last modification date: 2024-10-16)

Primary citation

Baquero, E.,Fedry, J.,Legrand, P.,Krey, T.,Rey, F.A.
Species-Specific Functional Regions of the Green Alga Gamete Fusion Protein HAP2 Revealed by Structural Studies.
Structure, 27:113-, 2019

PubMed Abstract: The cellular fusion protein HAP2, which is structurally homologous to viral class II fusion proteins, drives gamete fusion across several eukaryotic kingdoms. Gamete fusion is a highly controlled process in eukaryotes, and is allowed only between same species gametes. In spite of a conserved architecture, HAP2 displays several species-specific functional regions that were not resolved in the available X-ray structure of the green alga Chlamydomonas reinhardtii HAP2 ectodomain. Here we present an X-ray structure resolving these regions, showing a target membrane interaction surface made by three amphipathic helices in a horseshoe-shaped arrangement. HAP2 from green algae also features additional species-specific motifs inserted in regions that in viral class II proteins are critical for the fusogenic conformational change. Such insertions include a cystine ladder-like module evocative of EGF-like motifs responsible for extracellular protein-protein interactions in animals, and a mucin-like region. These features suggest potential HAP2 interaction sites involved in gamete fusion control.

PubMed: 30416037
DOI: 10.1016/j.str.2018.09.014

Experimental method

X-RAY DIFFRACTION (2.6 Å)