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Title: Site-directed mutagenesis of conserved Thr407, Asp433 and Met464 residues in small subunit of Escherichia coli ϒ-glutamyltranspeptidase
Authors: Lo, Huei-Fen
Lin, Long-Liu
Chen, Pei-Jing
Chou, Wei-Mou
Keywords: Escherichia coli;ϒ-Glutamyltranspeptidase;Site-directed mutagenesis;Autocatalytic processing
Issue Date: Aug-2007
Publisher: CSIR
Abstract: Sequence comparison showed that residues Thr407, Asp433, and Met464 in the small subunit of Escherichia coli ϒ -glutamyltranspeptidase (EcGGT) were conserved in the aligned enzymes. In this study, we further investigated the functional significance of these conserved residues by site-directed mutagenesis. The wild-type and mutant enzymes were overexpressed in the recombinant E. coli M15 cells and purified to near homogeneity by Ni²⁺-NTA resin. Except M464L, other mutants had shown no GGT activity under enzyme assay conditions and activity staining. Furthermore, mutations on these residues impaired the capability of autocatalytic processing of the enzyme. Based on these observations, it is concluded that these residues play an important role in the enzyme maturation.
Page(s): 197-203
ISSN: 0301-1208
Appears in Collections:IJBB Vol.44(4) [August 2007]

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