WD domain, G-beta repeat | |||||||||
---|---|---|---|---|---|---|---|---|---|
Identifiers | |||||||||
Symbol | WD40 | ||||||||
Pfam | PF00400 | ||||||||
Pfam clan | CL0186 | ||||||||
InterPro | IPR001680 | ||||||||
PROSITE | PDOC00574 | ||||||||
SCOP2 | 1gp2 / SCOPe / SUPFAM | ||||||||
CDD | cd00200 | ||||||||
|
In structural biology, a beta-propeller (β-propeller) is a type of all-β protein architecture characterized by 4 to 8 highly symmetrical blade-shaped beta sheets arranged toroidally around a central axis. Together the beta-sheets form a funnel-like active site.
Each beta-sheet typically has four anti-parallel β-strands arranged in the beta-zigzag motif. [2] The strands are twisted so that the first and fourth strands are almost perpendicular to each other. [3] There are five classes of beta-propellers, each arrangement being a highly symmetrical structure with 4–8 beta sheets, all of which generally form a central tunnel that yields pseudo-symmetric axes. [2]
While, the protein's official active site for ligand-binding is formed at one end of the central tunnel by loops between individual beta-strands, protein-protein interactions can occur at multiple areas around the domain. Depending on the packing and tilt of the beta-sheets and beta-strands, the beta-propeller may have a central pocket in place of a tunnel. [4]
The beta-propeller structure is stabilized mainly through hydrophobic interactions of the beta-sheets, while additional stability may come from hydrogen bonds formed between the beta-sheets of the C- and N-terminal ends. In effect this closes the circle which can occur even more strongly in 4-bladed proteins via a disulfide bond. [2] The chaperones Hsp70 and CCT have been shown to sequentially bind nascent beta-propellers as they emerge from the ribosome. These chaperones prevent non-native inter-blade interactions from forming until the entire beta-propeller is synthesized. [5] Many beta-propellers are dependent on CCT for expression. [6] [7] [8] In at least one case, ions have been shown to increase stability by binding deep in the central tunnel of the beta-propeller. [4]
Murzin proposed a geometric model to describe the structural principles of the beta propeller. [9] According to this model the seven bladed propeller was the most favored arrangement in geometric terms.
Despite its highly conserved nature, beta-propellers are well known for their plasticity. Beyond having a variety of allowed beta-sheets per domain, it can also accommodate other domains into its beta-sheets. Additionally, there are proteins that have shown variance in the number of beta-strands per beta-sheet. Rather than having the typical four beta-strands in a sheet, beta-lactamase inhibitor protein-II only has three beta-strands per sheet while the phytase of Bacillus subtilis has five beta-strands per beta-sheet. [2]
Due to its structure and plasticity, protein-protein interactions can form with the top, bottom, central channel, and side faces of the beta-propeller. [4] The function of the propeller can vary based on the blade number. Four-bladed beta-propellers function mainly as transport proteins, and because of its structure, they have a conformation that is favorable for substrate binding. [4] Unlike larger beta-propellers, four-bladed beta-propellers usually cannot perform catalysis themselves, but act instead to aid in catalysis by performing the aforementioned functions. Five-bladed propellers can act as transferases, hydrolases, and sugar binding proteins. [4] Six- and seven-bladed propellers perform a much broader variety of functions in comparison to four- and five-bladed propellers. These functions can include acting as ligand-binding proteins, hydrolases, lyases, isomerases, signaling proteins, structural proteins, and oxidoreductases. [4]
Variations in the larger (five- to eight-bladed) beta-propellers can allow for even more specific functions. This is the case with the C-terminal region of GyrA which expresses a positively charged surface ideal for binding DNA. Two alpha-helices coming out of the six-bladed beta-propeller of serum paraoxonase may provide a hydrophobic region ideal for anchoring membranes. DNA damage-binding protein 1 has three beta-propellers, in which the connection between two of the propellers is inserted into the third propeller potentially allowing for its unique function. [4]
Repeat domains known to fold into a beta-propeller include WD40, YWTD, Kelch, YVTN, RIVW (PD40), and many more. Their sequences tend to group together, suggesting a close evolutionary link. They are also related to many beta-containing domains. [19]
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: CS1 maint: multiple names: authors list (
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WD domain, G-beta repeat | |||||||||
---|---|---|---|---|---|---|---|---|---|
Identifiers | |||||||||
Symbol | WD40 | ||||||||
Pfam | PF00400 | ||||||||
Pfam clan | CL0186 | ||||||||
InterPro | IPR001680 | ||||||||
PROSITE | PDOC00574 | ||||||||
SCOP2 | 1gp2 / SCOPe / SUPFAM | ||||||||
CDD | cd00200 | ||||||||
|
In structural biology, a beta-propeller (β-propeller) is a type of all-β protein architecture characterized by 4 to 8 highly symmetrical blade-shaped beta sheets arranged toroidally around a central axis. Together the beta-sheets form a funnel-like active site.
Each beta-sheet typically has four anti-parallel β-strands arranged in the beta-zigzag motif. [2] The strands are twisted so that the first and fourth strands are almost perpendicular to each other. [3] There are five classes of beta-propellers, each arrangement being a highly symmetrical structure with 4–8 beta sheets, all of which generally form a central tunnel that yields pseudo-symmetric axes. [2]
While, the protein's official active site for ligand-binding is formed at one end of the central tunnel by loops between individual beta-strands, protein-protein interactions can occur at multiple areas around the domain. Depending on the packing and tilt of the beta-sheets and beta-strands, the beta-propeller may have a central pocket in place of a tunnel. [4]
The beta-propeller structure is stabilized mainly through hydrophobic interactions of the beta-sheets, while additional stability may come from hydrogen bonds formed between the beta-sheets of the C- and N-terminal ends. In effect this closes the circle which can occur even more strongly in 4-bladed proteins via a disulfide bond. [2] The chaperones Hsp70 and CCT have been shown to sequentially bind nascent beta-propellers as they emerge from the ribosome. These chaperones prevent non-native inter-blade interactions from forming until the entire beta-propeller is synthesized. [5] Many beta-propellers are dependent on CCT for expression. [6] [7] [8] In at least one case, ions have been shown to increase stability by binding deep in the central tunnel of the beta-propeller. [4]
Murzin proposed a geometric model to describe the structural principles of the beta propeller. [9] According to this model the seven bladed propeller was the most favored arrangement in geometric terms.
Despite its highly conserved nature, beta-propellers are well known for their plasticity. Beyond having a variety of allowed beta-sheets per domain, it can also accommodate other domains into its beta-sheets. Additionally, there are proteins that have shown variance in the number of beta-strands per beta-sheet. Rather than having the typical four beta-strands in a sheet, beta-lactamase inhibitor protein-II only has three beta-strands per sheet while the phytase of Bacillus subtilis has five beta-strands per beta-sheet. [2]
Due to its structure and plasticity, protein-protein interactions can form with the top, bottom, central channel, and side faces of the beta-propeller. [4] The function of the propeller can vary based on the blade number. Four-bladed beta-propellers function mainly as transport proteins, and because of its structure, they have a conformation that is favorable for substrate binding. [4] Unlike larger beta-propellers, four-bladed beta-propellers usually cannot perform catalysis themselves, but act instead to aid in catalysis by performing the aforementioned functions. Five-bladed propellers can act as transferases, hydrolases, and sugar binding proteins. [4] Six- and seven-bladed propellers perform a much broader variety of functions in comparison to four- and five-bladed propellers. These functions can include acting as ligand-binding proteins, hydrolases, lyases, isomerases, signaling proteins, structural proteins, and oxidoreductases. [4]
Variations in the larger (five- to eight-bladed) beta-propellers can allow for even more specific functions. This is the case with the C-terminal region of GyrA which expresses a positively charged surface ideal for binding DNA. Two alpha-helices coming out of the six-bladed beta-propeller of serum paraoxonase may provide a hydrophobic region ideal for anchoring membranes. DNA damage-binding protein 1 has three beta-propellers, in which the connection between two of the propellers is inserted into the third propeller potentially allowing for its unique function. [4]
Repeat domains known to fold into a beta-propeller include WD40, YWTD, Kelch, YVTN, RIVW (PD40), and many more. Their sequences tend to group together, suggesting a close evolutionary link. They are also related to many beta-containing domains. [19]
{{
cite book}}
: CS1 maint: multiple names: authors list (
link)
{{
cite book}}
: |work=
ignored (
help)