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Mutagenesis and Functional Selection Protocols for Directed Evolution of Proteins in E. coli
Published on: March 16, 2011
Evidence of positive Darwinian selection in Omp85, a highly conserved bacterial outer membrane protein essential for
David A Fitzpatrick1, James O McInerney
1Department of Biology, National University of Ireland, Maynooth, Country Kildare, Ireland.
Abstract:
Omp85 is a highly conserved outer membrane protein found in all gram-negative bacteria. It is essential for bacterial cell viability and plays an integral function in the positioning and folding of other outer membrane proteins into the bacterial outer membrane. We have employed a maximum likelihood and a maximum parsimony approach to detect evidence of positive Darwinian selection in Omp85 homologues from 10 delta-proteobacteria and have identified 14 amino acid sites that show evidence of being under the influence of adaptive evolution. Interestingly all sites bar one are concentrated within surface loops of the protein that most likely interact with host immune response or the surrounding environment. Alternatively amino acids within membrane-spanning regions of the protein are found to be under purifying selection most likely as a result of structural constraints.
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