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Journal of Bacteriology, March 2007, p. 1655-1663, Vol. 189, No. 5
0021-9193/07/$08.00+0     doi:10.1128/JB.01568-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Characterization of a Novel D-Lyxose Isomerase from Cohnella laevoribosii RI-39 sp. nov.{triangledown}

Eun-Ah Cho,1 Dong-Woo Lee,2 Yun-Hwan Cha,1 Sang-Jae Lee,1 Heung-Chae Jung,3,4 Jae-Gu Pan,3,4 and Yu-Ryang Pyun1*

Department of Biotechnology, Yonsei University, Seoul 120-749, Korea,1 Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6018,2 National Research Laboratory of Microbial Display, GenoFocus Inc., Daejeon 305-811, Korea,3 Systems Microbiology Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 305-333, Korea4

Received 10 October 2006/ Accepted 12 December 2006

A newly isolated bacterium, Cohnella laevoribosii RI-39, could grow in a defined medium with L-ribose as the sole carbon source. A 21-kDa protein isomerizing L-ribose to L-ribulose, as well as D-lyxose to D-xylulose, was purified to homogeneity from this bacterium. Based on the N-terminal and internal amino acid sequences of the purified enzyme obtained by N-terminal sequencing and quantitative time of flight mass spectrometry-mass spectrometry analyses, a 549-bp gene (lyxA) encoding D-lyxose (L-ribose) isomerase was cloned and expressed in Escherichia coli. The purified endogenous enzyme and the recombinant enzyme formed homodimers that were activated by Mn2+. C. laevoribosii D-lyxose (L-ribose) isomerase (CLLI) exhibits maximal activity at pH 6.5 and 70°C in the presence of Mn2+ for D-lyxose and L-ribose, and its isoelectric point (pI) is 4.2 (calculated pI, 4.9). The enzyme is specific for D-lyxose, L-ribose, and D-mannose, with apparent Km values of 22.4 ± 1.5 mM, 121.7 ± 10.8 mM, and 34.0 ± 1.1 mM, respectively. The catalytic efficiencies (kcat/Km) of CLLI were 84.9 ± 5.8 mM–1 s–1 for D-lyxose (Vmax, 5,434.8 U mg–1), 0.2 mM–1 s–1 for L-ribose (Vmax, 75.5 ± 6.0 U mg–1), and 1.4 ± 0.1 mM–1 s–1 for D-mannose (Vmax, 131.8 ± 7.4 U mg–1). The ability of lyxA to permit E. coli cells to grow on D-lyxose and L-ribose and homology searches of other sugar-related enzymes, as well as previously described sugar isomerases, suggest that CLLI is a novel type of rare sugar isomerase.

* Corresponding author. Mailing address: Department of Biotechnology, Yonsei University, Seoul 120-749, Korea. Phone: 82-2-2123-2883. Fax: 82-2-312-6821. E-mail: yrpyun{at}yonsei.ac.kr.

{triangledown} Published ahead of print on 22 December 2006.

Journal of Bacteriology, March 2007, p. 1655-1663, Vol. 189, No. 5
0021-9193/07/$08.00+0     doi:10.1128/JB.01568-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Yeom, S.-J., Ji, J.-H., Kim, N.-H., Park, C.-S., Oh, D.-K. (2009). Substrate Specificity of a Mannose-6-Phosphate Isomerase from Bacillus subtilis and Its Application in the Production of L-Ribose. Appl. Environ. Microbiol. 75: 4705-4710 [Abstract] [Full Text]  
  • Cho, E.-A., Lee, J.-S., Lee, K. C., Jung, H.-C., Pan, J.-G., Pyun, Y.-R. (2007). Cohnella laeviribosi sp. nov., isolated from a volcanic pond. Int. J. Syst. Evol. Microbiol. 57: 2902-2907 [Abstract] [Full Text]  


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