In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 98, No. 6 ( 2001-03-13), p. 3092-3097
Abstract:
The (β/α) 8 barrel is the most commonly
occurring fold among protein catalysts. To lay a groundwork for engineering novel barrel proteins, we investigated the amino acid
sequence restrictions at 182 structural positions of the prototypical (β/α) 8 barrel enzyme triosephosphate
isomerase. Using combinatorial mutagenesis and functional selection, we find that turn sequences, α-helix capping and stop motifs, and
residues that pack the interface between β-strands and α-helices are highly mutable. Conversely, any mutation of residues in the central
core of the β-barrel, β-strand stop motifs, and a single buried salt bridge between amino acids R189 and D227 substantially reduces
catalytic activity. Four positions are effectively immutable: conservative single substitutions at these four positions prevent the
mutant protein from complementing a triosephosphate isomerase knockout in Escherichia coli . At 142 of the 182 positions,
mutation to at least one amino acid of a seven-letter amino acid alphabet produces a triosephosphate isomerase with wild-type activity.
Consequently, it seems likely that (β/α) 8 barrel structures can be encoded with a subset of the 20 amino acids.
Such simplification would greatly decrease the computational burden of (β/α) 8 barrel design.
Type of Medium:
Online Resource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.041613598
Language:
English
Publisher:
Proceedings of the National Academy of Sciences
Publication Date:
2001
detail.hit.zdb_id:
209104-5
detail.hit.zdb_id:
1461794-8
SSG:
11
SSG:
12
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