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l ‐Glutamate Enhances the Expression of Thermus Maltogenic Amylase in Escherichia coli
Author(s) -
Jung HyungMoo,
Park KwanHwa,
Kim SangYong,
Lee JungKul
Publication year - 2008
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1021/bp034089z
Subject(s) - escherichia coli , thermus , superoxide dismutase , biochemistry , glutamate dehydrogenase , biology , bacteria , elongation factor , glutamate receptor , amylase , microbiology and biotechnology , chemistry , enzyme , rna , thermophile , ribosome , gene , genetics , receptor
Escherichia coli BL21 (DE3) transformed with a thermostable Thermus maltogenic amylase (ThMA), isolated from a Gram‐negative bacterium Thermus strain IM6501, grew well and efficiently produced ThMA in a complex medium but not in a chemically defined medium (DM). By supplementing l ‐glutamate to DM medium, both the specific growth rate and ThMA expression significantly increased. Alterations in the cellular responses of recombinant E. coli to l ‐glutamate were analyzed at the protein level by two‐dimensional gel electrophoresis and mass spectrometry. The ppGpp synthase (RelA) was significantly reduced in cells grown with l ‐glutamate and was consistent with the low level of ppGpp, an indicator of stringent response. On the other hand, protein chain elongation factor (EF‐Tu) and manganese‐containing superoxide dismutase (MnSOD), which protects cells against oxidative damage, was significantly elevated by l ‐glutamate supplementation. These results indicate that l ‐glutamate enhances ThMA expression and increases the E. coli growth rate not only by overcoming the stringent response but also by increasing the synthesis of EF‐Tu and MnSOD.