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A beta helix is a tandem protein repeat structure formed by the association of parallel beta sheet in a helical pattern with either two or three faces. The beta helix is a type of solenoid protein domain. The structure is stabilized by inter-strand hydrogen bonds, protein-protein interactions, and sometimes bound metal ions. Both left- and right-handed beta helices have been identified. These structures are distinct from jelly-roll folds, a different protein structure sometimes known as a "double-stranded beta helix".

The first beta-helix was observed in the enzyme pectate lyase, which contains a seven-turn helix that reaches 34 Å (3.4 nm) long. The P22 phage tail spike protein, a component of the P22 bacteriophage, has 13 turns and in its assembled homotrimer is 200 Å (20 nm) in length. Its interior is close-packed with no central pore and contains both hydrophobic residues and charged residues neutralized by salt bridges.

Both pectate lyase and P22 tailspike protein contain right-handed helices; left-handed versions have been observed in enzymes such as UDP-N-acetylglucosamine acyltransferase and archaeal carbonic anhydrase. Other proteins that contain beta helices include the antifreeze proteins from the beetle Tenebrio molitor (right-handed) and from the spruce budworm, Choristoneura fumiferana (left-handed), where regularly spaced threonines on the β-helices bind to the surface of ice crystals and inhibit their growth.

Beta helices can associate with each other effectively, either face-to-face (mating the faces of their triangular prisms) or end-to-end (forming hydrogen bonds). Hence, β-helices can be used as "tags" to induce other proteins to associate, similar to coiled coil segments.

Members of the pentapeptide repeat family have been shown to possess a quadrilateral beta-helix structure.

References

1. "CATH database - folds and homologous superfamilies within the beta 2-solenoid architecture". CATH database.
2. "CATH database - folds and homologous superfamilies within the beta 3-solenoid architecture". CATH database. Archived from the original on 26 July 2011.
3. Aik, WeiShen; McDonough, Michael A; Thalhammer, Armin; Chowdhury, Rasheduzzaman; Schofield, Christopher J (December 2012). "Role of the jelly-roll fold in substrate binding by 2-oxoglutarate oxygenases". Current Opinion in Structural Biology. 22 (6): 691–700. doi:10.1016/j.sbi.2012.10.001. PMID 23142576.
4. "Double-stranded beta-helix". SCOPe. Retrieved 29 November 2021.
5. Kisker C, Schindelin H, Alber BE, Ferry JG, Rees DC (May 1996). "A left-hand beta-helix revealed by the crystal structure of a carbonic anhydrase from the archaeon Methanosarcina thermophila". EMBO J. 15 (10): 2323–30. doi:10.1002/j.1460-2075.1996.tb00588.x. PMC 450161. PMID 8665839.
6. Liou YC, Tocilj A, Davies PL, Jia Z (July 2000). "Mimicry of ice structure by surface hydroxyls and water of a beta-helix antifreeze protein". Nature. 406 (6793): 322–4. Bibcode:2000Natur.406..322L. doi:10.1038/35018604. PMID 10917536. S2CID 4385352.
7. Leinala EK, Davies PL, Jia Z (May 2002). "Crystal structure of beta-helical antifreeze protein points to a general ice binding model". Structure. 10 (5): 619–27. doi:10.1016/s0969-2126(02)00745-1. PMID 12015145.
8. Vetting MW, Hegde SS, Fajardo JE, et al. (January 2006). "Pentapeptide repeat proteins". Biochemistry. 45 (1): 1–10. doi:10.1021/bi052130w. PMC 2566302. PMID 16388575.

External links

• SCOP family of right-handed β-helices
• SCOP family of left-handed β-helices
• CATH β-helix protein family

v t e Spirals, curves and helices
Curves	Algebraic Curvature Gallery List Topics
Helices	Angle Antenna Boerdijk–Coxeter Hemi Symmetry Triple Biochemistry 310 Alpha Beta Double Pi Polyproline Super Triple Collagen
Spirals	Archimedean Cotes's Epispiral Hyperbolic Poinsot's Doyle Euler Fermat's Involute List Logarithmic Golden On Spirals Padovan Pitch angle Theodorus Spirangle Ulam

• Protein tandem repeats
• Protein folds
• Helices