Document Detail

Poly-alpha-glutamic acid synthesis using a novel catalytic activity of RimK from Escherichia coli K-12.
MedLine Citation:
PMID:  21278279     Owner:  NLM     Status:  MEDLINE    
Poly-L-α-amino acids have various applications because of their biodegradable properties and biocompatibility. Microorganisms contain several enzymes that catalyze the polymerization of L-amino acids in an ATP-dependent manner, but the products from these reactions contain amide linkages at the side residues of amino acids: e.g., poly-γ-glutamic acid, poly-ε-lysine, and cyanophycin. In this study, we found a novel catalytic activity of RimK, a ribosomal protein S6-modifying enzyme derived from Escherichia coli K-12. This enzyme catalyzed poly-α-glutamic acid synthesis from unprotected L-glutamic acid (Glu) by hydrolyzing ATP to ADP and phosphate. RimK synthesized poly-α-glutamic acid of various lengths; matrix-assisted laser desorption ionization-time of flight-mass spectrometry showed that a 46-mer of Glu (maximum length) was synthesized at pH 9. Interestingly, the lengths of polymers changed with changing pH. RimK also exhibited 86% activity after incubation at 55°C for 15 min, thus showing thermal stability. Furthermore, peptide elongation seemed to be catalyzed at the C terminus in a stepwise manner. Although RimK showed strict substrate specificity toward Glu, it also used, to a small extent, other amino acids as C-terminal substrates and synthesized heteropeptides. In addition, RimK-catalyzed modification of ribosomal protein S6 was confirmed. The number of Glu residues added to the protein varied with pH and was largest at pH 9.5.
Kuniki Kino; Toshinobu Arai; Yasuhiro Arimura
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2011-01-28
Journal Detail:
Title:  Applied and environmental microbiology     Volume:  77     ISSN:  1098-5336     ISO Abbreviation:  Appl. Environ. Microbiol.     Publication Date:  2011 Mar 
Date Detail:
Created Date:  2011-03-11     Completed Date:  2011-06-22     Revised Date:  2013-06-30    
Medline Journal Info:
Nlm Unique ID:  7605801     Medline TA:  Appl Environ Microbiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2019-25     Citation Subset:  IM    
Department of Applied Chemistry, Faculty of Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555, Japan.
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MeSH Terms
Escherichia coli K12 / enzymology*
Escherichia coli Proteins / metabolism*
Glutamic Acid / chemistry*
Hydrogen-Ion Concentration
Magnetic Resonance Spectroscopy
Molecular Sequence Data
Peptides / chemical synthesis*,  chemistry*
Polylysine / chemical synthesis*,  chemistry
Spectrometry, Mass, Electrospray Ionization
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
Reg. No./Substance:
0/Escherichia coli Proteins; 0/Peptides; 25104-18-1/Polylysine; 56-86-0/Glutamic Acid

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