Nature versus nurture in two highly enantioselective esterases from Bacillus cereus and Thermoanaerobacter tengcongensis

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DOIResolve DOI: http://doi.org/10.1111/j.1751-7915.2009.00142.x
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TypeArticle
Journal titleMicrobial Biotechnology
Volume3
Issue1
Pages131; # of pages: 31
Subjectbiocatalysis; hydrolase; thermostability; directed evolution; drug synthesis; green chemistry
AbstractThere is an increasing need for the use of biocatalysis to obtain enantiopure compounds as chiral building blocks for drug synthesis such as antibiotics. The principal findings of this study are: i) the complete sequenced genomes of Bacillus cereus ATCC 14579 and Thermoanaerobacter tengcongensis MB4 contain a hitherto undescribed enantioselective and alkaliphilic esterase (BcEST and TtEST, respectively) that is specific for the production of (R)-2-benzyloxy-propionic acid ethyl ester, a key intermediate in the synthesis of levofloxacin, a potent antibiotic; and, ii) directed evolution targeted for increased thermostability of BcEST produced two improved variants, but in either case the 3 – 5°C increase in the apparent melting temperature (Tm) of the mutants over the native BcEST that has a Tm of 50°C was outperformed by TtEST, a naturally-occurring homolog with a Tm of 65°C. Protein modeling of BcEST mapped the S148C and K272R mutations at protein surface and the I88T and Q110L mutations at more buried locations. This work expands the repertoire of characterized members of the α/β fold-hydrolase superfamily. Further, it shows that genome mining is an economical option for new biocatalyst discovery and we provide a rare example of a naturally-occurring thermostable biocatalyst that outperforms experimentally-evolved homologs that carry out the same hydrolysis.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); NRC Biotechnology Research Institute
Peer reviewedYes
NRC number50005
NPARC number14145436
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Record identifier03db407d-cae6-43b9-a9fb-371315081dc0
Record created2010-06-02
Record modified2016-05-09
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