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Thesis

Computational studies of protein helix kinks

Abstract:

Kinks are functionally important structural features found in the alpha-helices of many proteins, particularly membrane proteins. Structurally, they are points at which a helix abruptly changes direction. Previous kink definition and identification methods often disagree with one another.

Here I describe three novel methods to characterise kinks, which improve on existing approaches. First, Kink Finder, a computational method that consistently locates kinks and estimates the error in the kink angle. Second the B statistic, a statistically robust method for identifying kinks. Third, Alpha Helices Assessed by Humans, a crowdsourcing approach that provided a gold-standard data set on which to train and compare existing kink identification methods.

In this thesis, I show that kinks are a feature of long -helices in both soluble and membrane proteins, rather than just transmembrane -helices. Characteristics of kinks in the two types of proteins are similar, with Proline being the dominant feature in both types of protein. In soluble proteins, kinked helices also have a clear structural preference in that they typically point into the solvent.

I also explored the conservation of kinks in homologous proteins. I found examples of conserved and non-conserved kinks in both the helix pairs and the helix families. Helix pairs with non-conserved kinks generally have less similar sequences than helix pairs with conserved kinks. I identified helix families that show highly conserved kinks, and families that contain non-conserved kinks, suggesting that some kinks may be flexible points in protein structures.

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Institution:
University of Oxford
Division:
MPLS
Department:
Statistics
Research group:
Oxford Protein Informatics Group
Oxford college:
Hertford College
Role:
Author
More by this author
Division:
MPLS
Department:
Statistics
Role:
Author

Contributors

Division:
MPLS
Department:
Statistics
Role:
Supervisor
Division:
MPLS
Department:
Statistics
Role:
Supervisor


More from this funder
Funding agency for:
Wilman, H
Grant:
EP/G037280/1


Publication date:
2014
DOI:
Type of award:
DPhil
Level of award:
Doctoral
Awarding institution:
Oxford University, UK

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