Coiled Coils

Figure 1: Schematic diagram of coiled coil periodicities in relation to the numbers of residues per turn, the sequence repeat length and the number of helical turns per repeat

α-helical coiled coils are ubiquitous elements of protein structure, formed by two or more helices wound in a superhelical array [1]. Though generally of fibrous appearance, coiled coils become progressively barrel-like as their number of constituent helices increases and they start enclosing a central, solvent-filled channel. Due to their intrinsic stability, coiled coils are widely used in biology to provide mechanically and chemically resilient fibers, oligomerization platforms, scaffolds for protein complex assembly, stalks and arms for molecular machines [2], levers for membrane fusion and channels for solute transport.

We have been interested in coiled coils for a long time, studying their properties [1] and classifying their structural diversity [3] [Figure 1]. Uniquely among proteins, their tertiary structure has been fully parametrized, making them particularly attractive for protein design [4], protein structure prediction [5,6] and quantitative analysis [7] projects.

Over the years we have applied our theoretical insights to a wide range of proteins; our main current focus in this area is on bacterial Trimeric Autotransporter Adhesins (TAAs) [4] and  transmembrane receptors [8].  We have also started to design new coiled coils with unusual core residues and odd periodicities.

References

 

[1] Lupas A., Gruber M. (2005) The structure of α-helical coiled coils. Adv Protein Chem 70:37-78
PMID: 15837513

 

[2] Martin J., Gruber M., Lupas A. (2004) Coiled coils meet the chaperone world. Trends Biochem Sci 29(9):455-8
PMID: 15337117

 

[3] Gruber M., Lupas AN. (2003) Historical review: another 50th anniversary – new periodicities in coiled coils. Trends Biochem Sci 28(12):679-85
PMID: 14659700

 

[4] Hartmann MD., Ridderbusch O., Zeth K., Albrecht R., Testa O., Woolfson DN., Sauer G., Dunin-Horkawicz S., Lupas AN., Hernandez Alvarez B. (2009) A coiled coil motif that sequesters ions to the hydrophobic core. Proc Natl Acad Sci USA 106(40):16950-5
PMID: 19805097

 

[5] Gruber M., Söding J., Lupas AN. (2006) Comparative analysis of coiled-coil prediction methods. J Struct Biol 155(2):140-5
PMID: 16870472

 

[6] Gruber M., Söding J., Lupas AN. (2005) REPPER – REPeats and their PERiodicities in fibrous proteins. Nucleic Acids Res 33(Web Server Issue):W239-W243
PMID: 15980460

 

[7] Dunin-Horkawicz S., Lupas AN. (2010) Measuring the conformational space of square four-helical bundles with the program samCC. J Struct Biol 170(2):226-35
PMID: 20139000

 

[8] Hulko M., Berndt F., Gruber M., Linder JU., Truffault V., Schultz A., Martin J., Schultz JE., Lupas AN., Coles M. (2006) The HAMP Domain Structure Implies Helix Rotation in Transmembrane Signaling. Cell 126: 929-940
PMID: 16959572