6DBS

Fusion surface structure, function, and dynamics of gamete fusogen HAP2

Summary for 6DBS

• Entry DOI: 10.2210/pdb6dbs/pdb
• Descriptor: Hapless 2, beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, alpha-D-mannopyranose-(1-6)-beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, ... (5 entities in total)
• Functional Keywords: gamete fertilization, cell fusogens, class ii fusion proteins, hydrogen deuterium exchange, structural protein
• Biological source: Chlamydomonas reinhardtii (Chlamydomonas smithii)
• Total number of polymer chains: 3
• Total formula weight: 183883.05

Authors

Feng, J.,Dong, X.,Springer, T.A. (deposition date: 2018-05-03, release date: 2018-09-19, Last modification date: 2024-11-06)

Primary citation

Feng, J.,Dong, X.,Pinello, J.,Zhang, J.,Lu, C.,Iacob, R.E.,Engen, J.R.,Snell, W.J.,Springer, T.A.
Fusion surface structure, function, and dynamics of gamete fusogen HAP2.
Elife, 7:-, 2018

PubMed Abstract: HAP2 is a class II gamete fusogen in many eukaryotic kingdoms. A crystal structure of HAP2 shows a trimeric fusion state. Domains D1, D2.1 and D2.2 line the 3-fold axis; D3 and a stem pack against the outer surface. Surprisingly, hydrogen-deuterium exchange shows that surfaces of D1, D2.2 and D3 closest to the 3-fold axis are more dynamic than exposed surfaces. Three fusion helices in the fusion loops of each monomer expose hydrophobic residues at the trimer apex that are splayed from the 3-fold axis, leaving a solvent-filled cavity between the fusion loops in each monomer. At the base of the two fusion loops, Arg185 docks in a carbonyl cage. Comparisons to other structures, dynamics, and the greater effect on gamete fusion of mutation of axis-proximal than axis-distal fusion helices suggest that the apical portion of each monomer could tilt toward the 3-fold axis with merger of the fusion helices into a common fusion surface.

PubMed: 30281023
DOI: 10.7554/eLife.39772

Experimental method

X-RAY DIFFRACTION (2.602 Å)