Poly-α-glutamic acid synthesis using a novel catalytic activity of Rimk from Escherichia coli K-12

Kuniki Kino, Toshinobu Arai, Yasuhiro Arimura

    Research output: Contribution to journalArticle

    13 Citations (Scopus)

    Abstract

    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.

    Original languageEnglish
    Pages (from-to)2019-2025
    Number of pages7
    JournalApplied and Environmental Microbiology
    Volume77
    Issue number6
    DOIs
    Publication statusPublished - 2011 Mar

    Fingerprint

    polyglutamic acid
    Escherichia coli K12
    catalytic activity
    Glutamic Acid
    amino acid
    Ribosomal Protein S6
    Escherichia coli
    Amino Acids
    amino acids
    synthesis
    acid
    ribosomal proteins
    enzyme
    protein
    Enzymes
    enzymes
    Adenosine Triphosphate
    biocompatibility
    substrate
    biodegradability

    ASJC Scopus subject areas

    • Applied Microbiology and Biotechnology
    • Food Science
    • Biotechnology
    • Ecology

    Cite this

    Poly-α-glutamic acid synthesis using a novel catalytic activity of Rimk from Escherichia coli K-12. / Kino, Kuniki; Arai, Toshinobu; Arimura, Yasuhiro.

    In: Applied and Environmental Microbiology, Vol. 77, No. 6, 03.2011, p. 2019-2025.

    Research output: Contribution to journalArticle

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