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

Kuniki Kino*, Toshinobu Arai, Yasuhiro Arimura

*この研究の対応する著者

研究成果: Article査読

27 被引用数 (Scopus)

抄録

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.

本文言語English
ページ(範囲)2019-2025
ページ数7
ジャーナルApplied and Environmental Microbiology
77
6
DOI
出版ステータスPublished - 2011 3月

ASJC Scopus subject areas

  • バイオテクノロジー
  • 食品科学
  • 応用微生物学とバイオテクノロジー
  • 生態学

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