Beta-propeller

WD domain, G-beta repeat
File:1erj 7bladed beta propeller.png Ribbon diagram of the C-terminal WD40 domain of Tup1 (a transcriptional co-repressor in yeast), which adopts a 7-bladed beta-propeller fold. Ribbon is colored from blue (N-terminus) to red (C-terminus). PDB 1erj
Identifiers
Symbol	WD40
Pfam	PF00400
Pfam clan	CL0186
InterPro	IPR001680
PROSITE	PDOC00574
SCOP	1gp2
SUPERFAMILY	1gp2
CDD	cd00200
Available protein structures: Pfam structures PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

In structural biology, a beta-propeller is a type of all-β protein architecture characterized by 4 to 8 blade-shaped beta sheets arranged toroidally around a central axis. Each sheet typically has four antiparallel β-strands twisted so that the first and fourth strands are almost perpendicular to each other. The enzyme's active site is often found in the cleft formed in the center of the propeller by loops connecting the successive four-sheet motifs. Murzin proposed a geometric model to describe the structural principles of the beta propeller. According to this model the seven bladed propeller was the most favoured arrangement in geometric terms.

Examples

The influenza virus protein viral neuraminidase is a six-bladed beta-propeller protein whose active form is a tetramer. It is one of two proteins present in the viral envelope and catalyzes the cleavage of sialic acid moieties from cell-membrane proteins to aid in the targeting of newly produced virions to previously uninfected cells.

The plant UV-B sensing protein UVR8 is a seven-bladed propeller which is dimeric until absorption of UV-B light, which causes dissociation.

WD40 repeats, also known as beta-transducin repeats, are short fragments found primarily in eukaryotes. They are often assembled in 4 to 16 repeated units to form a structural domain critical for protein-protein interactions.

A beta-propeller is a critical component of LDLR (low density lipoprotein receptor) and aids in a pH based conformational change. At neutral pH the LDLR receptor is in an extended linear conformation and can bind ligands (PCSK9). At acidic pH the linear conformation changes to a hairpin structure such that ligand binding sites bind to the beta-propeller, preventing ligand binding.

External links

• SCOP 4-bladed beta propellers
• SCOP 5-bladed beta propellers
• SCOP 6-bladed beta propellers
• SCOP 7-bladed beta propellers
• SCOP 8-bladed beta propellers

Further reading

• Branden C, Tooze J. (1999). Introduction to Protein Structure 2nd ed. Garland Publishing: New York, NY.