Active site loop conformation regulates promiscuous activity in a lactonase from Geobacillus kaustophilus HTA426.

Enzyme promiscuity is a prerequisite for fast divergent evolution of biocatalysts. A phosphotriesterase-like lactonase (PLL) from Geobacillus kaustophilus HTA426 (GkaP) exhibits main lactonase and promiscuous phosphotriesterase activities. To understand its catalytic and evolutionary mechanisms, we...

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Main Authors: Yu Zhang, Jiao An, Guang-Yu Yang, Aixi Bai, Baisong Zheng, Zhiyong Lou, Geng Wu, Wei Ye, Hai-Feng Chen, Yan Feng, Giuseppe Manco
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2015-01-01
Series:PLoS ONE
Online Access:https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0115130&type=printable
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author Yu Zhang
Jiao An
Guang-Yu Yang
Aixi Bai
Baisong Zheng
Zhiyong Lou
Geng Wu
Wei Ye
Hai-Feng Chen
Yan Feng
Giuseppe Manco
author_facet Yu Zhang
Jiao An
Guang-Yu Yang
Aixi Bai
Baisong Zheng
Zhiyong Lou
Geng Wu
Wei Ye
Hai-Feng Chen
Yan Feng
Giuseppe Manco
author_sort Yu Zhang
collection DOAJ
description Enzyme promiscuity is a prerequisite for fast divergent evolution of biocatalysts. A phosphotriesterase-like lactonase (PLL) from Geobacillus kaustophilus HTA426 (GkaP) exhibits main lactonase and promiscuous phosphotriesterase activities. To understand its catalytic and evolutionary mechanisms, we investigated a "hot spot" in the active site by saturation mutagenesis as well as X-ray crystallographic analyses. We found that position 99 in the active site was involved in substrate discrimination. One mutant, Y99L, exhibited 11-fold improvement over wild-type in reactivity (kcat/Km) toward the phosphotriesterase substrate ethyl-paraoxon, but showed 15-fold decrease toward the lactonase substrate δ-decanolactone, resulting in a 157-fold inversion of the substrate specificity. Structural analysis of Y99L revealed that the mutation causes a ∼6.6 Å outward shift of adjacent loop 7, which may cause increased flexibility of the active site and facilitate accommodation and/or catalysis of organophosphate substrate. This study provides for the PLL family an example of how the evolutionary route from promiscuity to specificity can derive from very few mutations, which promotes alteration in the conformational adjustment of the active site loops, in turn draws the capacity of substrate binding and activity.
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spelling doaj-art-079a04a85de64d54abeafb5802a1aa7b2025-08-20T02:15:01ZengPublic Library of Science (PLoS)PLoS ONE1932-62032015-01-01102e011513010.1371/journal.pone.0115130Active site loop conformation regulates promiscuous activity in a lactonase from Geobacillus kaustophilus HTA426.Yu ZhangJiao AnGuang-Yu YangAixi BaiBaisong ZhengZhiyong LouGeng WuWei YeHai-Feng ChenYan FengGiuseppe MancoEnzyme promiscuity is a prerequisite for fast divergent evolution of biocatalysts. A phosphotriesterase-like lactonase (PLL) from Geobacillus kaustophilus HTA426 (GkaP) exhibits main lactonase and promiscuous phosphotriesterase activities. To understand its catalytic and evolutionary mechanisms, we investigated a "hot spot" in the active site by saturation mutagenesis as well as X-ray crystallographic analyses. We found that position 99 in the active site was involved in substrate discrimination. One mutant, Y99L, exhibited 11-fold improvement over wild-type in reactivity (kcat/Km) toward the phosphotriesterase substrate ethyl-paraoxon, but showed 15-fold decrease toward the lactonase substrate δ-decanolactone, resulting in a 157-fold inversion of the substrate specificity. Structural analysis of Y99L revealed that the mutation causes a ∼6.6 Å outward shift of adjacent loop 7, which may cause increased flexibility of the active site and facilitate accommodation and/or catalysis of organophosphate substrate. This study provides for the PLL family an example of how the evolutionary route from promiscuity to specificity can derive from very few mutations, which promotes alteration in the conformational adjustment of the active site loops, in turn draws the capacity of substrate binding and activity.https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0115130&type=printable
spellingShingle Yu Zhang
Jiao An
Guang-Yu Yang
Aixi Bai
Baisong Zheng
Zhiyong Lou
Geng Wu
Wei Ye
Hai-Feng Chen
Yan Feng
Giuseppe Manco
Active site loop conformation regulates promiscuous activity in a lactonase from Geobacillus kaustophilus HTA426.
PLoS ONE
title Active site loop conformation regulates promiscuous activity in a lactonase from Geobacillus kaustophilus HTA426.
title_full Active site loop conformation regulates promiscuous activity in a lactonase from Geobacillus kaustophilus HTA426.
title_fullStr Active site loop conformation regulates promiscuous activity in a lactonase from Geobacillus kaustophilus HTA426.
title_full_unstemmed Active site loop conformation regulates promiscuous activity in a lactonase from Geobacillus kaustophilus HTA426.
title_short Active site loop conformation regulates promiscuous activity in a lactonase from Geobacillus kaustophilus HTA426.
title_sort active site loop conformation regulates promiscuous activity in a lactonase from geobacillus kaustophilus hta426
url https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0115130&type=printable
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