期刊
FRONTIERS IN MICROBIOLOGY
卷 9, 期 -, 页码 -出版社
FRONTIERS MEDIA SA
DOI: 10.3389/fmicb.2018.00167
关键词
alginate lyase; action mode; Flammeovirga; monosaccharide; oligosaccharide-yielding properties
类别
资金
- National Natural Science Foundation of China [31570071, 31300664]
- Science and Technology Development Project of Shandong Province [2016GGH4502]
- Science and Technology Special Project of Shandong Province [2015zdjs04002]
- Independent Innovation Plan of Colleges and Universities in Jinan [201401242]
- Fundamental Research Funds of Shandong University [2015JC002]
Endo-type alginate lyases usually degrade alginate completely into various size-defined unsaturated oligosaccharide products (>= disaccharides), while exoenzymes primarily produce monosaccharide products including saturated mannuronate (M) and guluronate (G) units and particularly unsaturated Delta units. Recently, two bifunctional alginate lyases have been identified as endolytic but M-and G-producing with variable action modes. However, endolytic Delta-producing alginate lyases remain undiscovered. Herein, a new Flammeovirga protein, Aly2, was classified into the polysaccharide lyase 7 superfamily. The recombinant enzyme and its truncated protein showed similar stable biochemical characteristics. Using different sugar chains as testing substrates, we demonstrated that the two enzymes are bifunctional while G-preferring, endolytic whereas monosaccharide-producing. Furthermore, the catalytic module of Aly2 can vary the action modes depending on the terminus type, molecular size, and M/G content of the substrate, thereby yielding different levels of M, G, and Delta units. Notably, the enzymes preferentially produce Delta units when digesting small size-defined oligosaccharide substrates, particularly the smallest substrate (unsaturated tetrasaccharide fractions). Deletion of the non-catalytic region of Aly2 caused weak changes in the action modes and biochemical characteristics. This study provided extended insights into alginate lyase groups with variable action modes for accurate enzyme use.
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