scholarly journals Identification of a Novel Alkaliphilic Esterase Active at Low Temperatures by Screening a Metagenomic Library from Antarctic Desert Soil

2009 ◽  
Vol 75 (13) ◽  
pp. 4657-4659 ◽  
Author(s):  
Caroline Heath ◽  
Xiao Ping Hu ◽  
S. Craig Cary ◽  
Donald Cowan
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Low Temperatures ◽  
Metagenomic Library ◽  
Desert Soil ◽  
Functional Screening ◽  
Potential Candidate ◽  
Alkaline Ph ◽  
Burkholderia Xenovorans ◽  
Novel Esterase

ABSTRACT A novel esterase was identified through functional screening of a metagenomic library in Escherichia coli obtained from Antarctic desert soil. The 297-amino-acid sequence had only low (<29%) similarity to a putative esterase from Burkholderia xenovorans. The enzyme was active over a temperature range of 7 to 54°C and at alkaline pH levels and is a potential candidate for industrial application.

scholarly journals New Thermophilic and Thermostable Esterase with Sequence Similarity to the Hormone-Sensitive Lipase Family, Cloned from a Metagenomic Library

2005 ◽  
Vol 71 (2) ◽  
pp. 817-825 ◽  
Author(s):  
Jin-Kyu Rhee ◽  
Dae-Gyun Ahn ◽  
Yeon-Gu Kim ◽  
Jong-Won Oh
Keyword(s):  
Amino Acid ◽  
Lipolytic Activity ◽  
Sequence Similarity ◽  
Acyl Chain ◽  
Metagenomic Library ◽  
Environmental Dna ◽  
Hormone Sensitive Lipase ◽  
Functional Screening ◽  
E Coli ◽  
Hormone Sensitive

ABSTRACT A gene coding for a thermostable esterase was isolated by functional screening of Escherichia coli cells that had been transformed with fosmid environmental DNA libraries constructed with metagenomes from thermal environmental samples. The gene conferring esterase activity on E. coli grown on tributyrin agar was composed of 936 bp, corresponding to 311 amino acid residues with a molecular mass of 34 kDa. The enzyme showed significant amino acid similarity (64%) to the enzyme from a hyperthermophilic archaeon, Pyrobaculum calidifontis. An amino acid sequence comparison with other esterases and lipases revealed that the enzyme should be classified as a new member of the hormone-sensitive lipase family. The recombinant esterase that was overexpressed and purified from E. coli was active above 30°C up to 95°C and had a high thermal stability. It displayed a high degree of activity in a pH range of 5.5 to 7.5, with an optimal pH of approximately 6.0. The best substrate for the enzyme among the p-nitrophenyl esters (C4 to C16) examined was p-nitrophenyl caproate (C6), and no lipolytic activity was observed with esters containing an acyl chain length of longer than 10 carbon atoms, indicating that the enzyme is an esterase and not a lipase.

scholarly journals Amino acid substitutions and alteration in cation specificity in the melibiose carrier of Escherichia coli.

1988 ◽  
Vol 263 (28) ◽  
pp. 14276-14280 ◽  
Author(s):  
T Kawakami ◽  
Y Akizawa ◽  
T Ishikawa ◽  
T Shimamoto ◽  
M Tsuda ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Amino Acid Substitutions
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