Applying neutral drift to the directed molecular evolution of a β-glucuronidase into a β-galactosidase: Two different evolutionary pathways lead to the same variant

Background: Directed protein evolution has been used to modify protein activity and research has been carried out to enhance the production of high quality mutant libraries. Many theoretical approaches suggest that allowing a population to undergo neutral selection may be valuable in directed evolut...

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Main Authors: Smith, W.S., Hale, J.R., Neylon, Cameron
Format: Journal Article
Language:English
Published: 2011
Online Access:http://hdl.handle.net/20.500.11937/81474
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author Smith, W.S.
Hale, J.R.
Neylon, Cameron
author_facet Smith, W.S.
Hale, J.R.
Neylon, Cameron
author_sort Smith, W.S.
building Curtin Institutional Repository
collection Online Access
description Background: Directed protein evolution has been used to modify protein activity and research has been carried out to enhance the production of high quality mutant libraries. Many theoretical approaches suggest that allowing a population to undergo neutral selection may be valuable in directed evolution experiments. Findings. Here we report on an investigation into the value of neutral selection in a classical model system for directed evolution, the conversion of the E. coli -glucuronidase to a -galactosidase activity. We find that neutral selection, i.e. selection for retaining glucuronidase activity, can efficiently identify the majority of sites of mutation that have been identified as beneficial for galactosidase activity in previous experiments. Each variant demonstrating increased galactosidase activity identified by our neutral drift experiments contained a mutation at one of four sites, T509, S557, N566 or W529. All of these sites have previously been identified using direct selection for beta galactosidase activity. Conclusions: Our results are consistent with others that show that a neutral selection approach can be effective in selecting improved variants. However, we interpret our results to show that neutral selection is, in this case, not a more efficient approach than conventional directed evolution approaches. However, the neutral approach is likely to be beneficial when the resulting library can be screened for a range of related activities. More detailed statistical studies to resolve the apparent differences between this system and others are likely to be a fruitful avenue for future research. © 2011 Neylon et al; licensee BioMed Central Ltd.
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spelling curtin-20.500.11937-814742020-11-09T02:24:59Z Applying neutral drift to the directed molecular evolution of a β-glucuronidase into a β-galactosidase: Two different evolutionary pathways lead to the same variant Smith, W.S. Hale, J.R. Neylon, Cameron Background: Directed protein evolution has been used to modify protein activity and research has been carried out to enhance the production of high quality mutant libraries. Many theoretical approaches suggest that allowing a population to undergo neutral selection may be valuable in directed evolution experiments. Findings. Here we report on an investigation into the value of neutral selection in a classical model system for directed evolution, the conversion of the E. coli -glucuronidase to a -galactosidase activity. We find that neutral selection, i.e. selection for retaining glucuronidase activity, can efficiently identify the majority of sites of mutation that have been identified as beneficial for galactosidase activity in previous experiments. Each variant demonstrating increased galactosidase activity identified by our neutral drift experiments contained a mutation at one of four sites, T509, S557, N566 or W529. All of these sites have previously been identified using direct selection for beta galactosidase activity. Conclusions: Our results are consistent with others that show that a neutral selection approach can be effective in selecting improved variants. However, we interpret our results to show that neutral selection is, in this case, not a more efficient approach than conventional directed evolution approaches. However, the neutral approach is likely to be beneficial when the resulting library can be screened for a range of related activities. More detailed statistical studies to resolve the apparent differences between this system and others are likely to be a fruitful avenue for future research. © 2011 Neylon et al; licensee BioMed Central Ltd. 2011 Journal Article http://hdl.handle.net/20.500.11937/81474 10.1186/1756-0500-4-138 eng http://creativecommons.org/licenses/by/4.0/ fulltext
spellingShingle Smith, W.S.
Hale, J.R.
Neylon, Cameron
Applying neutral drift to the directed molecular evolution of a β-glucuronidase into a β-galactosidase: Two different evolutionary pathways lead to the same variant
title Applying neutral drift to the directed molecular evolution of a β-glucuronidase into a β-galactosidase: Two different evolutionary pathways lead to the same variant
title_full Applying neutral drift to the directed molecular evolution of a β-glucuronidase into a β-galactosidase: Two different evolutionary pathways lead to the same variant
title_fullStr Applying neutral drift to the directed molecular evolution of a β-glucuronidase into a β-galactosidase: Two different evolutionary pathways lead to the same variant
title_full_unstemmed Applying neutral drift to the directed molecular evolution of a β-glucuronidase into a β-galactosidase: Two different evolutionary pathways lead to the same variant
title_short Applying neutral drift to the directed molecular evolution of a β-glucuronidase into a β-galactosidase: Two different evolutionary pathways lead to the same variant
title_sort applying neutral drift to the directed molecular evolution of a β-glucuronidase into a β-galactosidase: two different evolutionary pathways lead to the same variant
url http://hdl.handle.net/20.500.11937/81474