In the present study, we characterized the gene (Cyanobase accession number slr0897) designated Ssglc encoding a β-1,4-glucanase-like protein (SsGlc) from Synechocystis PCC6803. The deduced amino acid sequence for Ssglc showed a high degree of similarity to sequences of GH (glycoside hydrolase) family 9 β-1,4-glucanases (cellulases) from various sources. Surprisingly, the recombinant protein obtained from the Escherichia coli expression system was able to hydrolyse barley β-glucan and lichenan (β-1,3-1,4-glucan), but not cellulose (β-1,4-glucan), curdlan (β-1,3-glucan), or laminarin (β-1,3-1,6-glucan). A 1H-NMR analysis of the enzymatic products revealed that the enzyme hydrolyses the β-1,4-glycosidic linkage of barley β-glucan through an inverting mechanism. The data indicated that SsGlc was a novel type of GH9 glucanase which could specifically hydrolyse the β-1,3-1,4-linkage of glucan. The growth of mutant Synechocystis cells in which the Ssglc gene was disrupted by a kanamycin-resistance cartridge gene was almost the same as that of the wild-type cells under continuous light (40 μmol of photons/m2 per s), a 12 h light (40 μmol of photons/m2 per s)/12 h dark cycle, cold stress (4 °C), and high light stress (200 μmol of photons/m2 per s). However, under salt stress (300–450 mM NaCl), growth of the Ssglc-disrupted mutant cells was significantly inhibited as compared with that of the wild-type cells. The Ssglc-disrupted mutant cells showed a decreased rate of O2 consumption and NaHCO3-dependent O2 evolution as compared with the wild-type cells under salt stress. Under osmotic stress (100–400 mM sorbitol), there was no difference in growth between the wild-type and the Ssglc-disrupted mutant cells. These results suggest that SsGlc functions in salt stress tolerance in Synechocystis PCC6803.
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Research Article|
June 13 2007
β-1,4-Glucanase-like protein from the cyanobacterium Synechocystis PCC6803 is a β-1,3-1,4-glucanase and functions in salt stress tolerance
Masahiro Tamoi;
Masahiro Tamoi
1Department of Advanced Bioscience, Faculty of Agriculture, Kinki University, 3327–204 Nakamachi, Nara 631–8505, Japan
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Hideki Kurotaki;
Hideki Kurotaki
1Department of Advanced Bioscience, Faculty of Agriculture, Kinki University, 3327–204 Nakamachi, Nara 631–8505, Japan
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Tamo Fukamizo
Tamo Fukamizo
1
1Department of Advanced Bioscience, Faculty of Agriculture, Kinki University, 3327–204 Nakamachi, Nara 631–8505, Japan
1To whom correspondence should be addressed (email fukamizo@nara.kindai.ac.jp).
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Publisher: Portland Press Ltd
Received:
February 01 2007
Revision Received:
February 23 2007
Accepted:
March 01 2007
Accepted Manuscript online:
March 01 2007
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2007 Biochemical Society
2007
Biochem J (2007) 405 (1): 139–146.
Article history
Received:
February 01 2007
Revision Received:
February 23 2007
Accepted:
March 01 2007
Accepted Manuscript online:
March 01 2007
Citation
Masahiro Tamoi, Hideki Kurotaki, Tamo Fukamizo; β-1,4-Glucanase-like protein from the cyanobacterium Synechocystis PCC6803 is a β-1,3-1,4-glucanase and functions in salt stress tolerance. Biochem J 1 July 2007; 405 (1): 139–146. doi: https://doi.org/10.1042/BJ20070171
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