Biology:Xanthan lyase
The enzyme xanthan lyase (EC 4.2.2.12) catalyzes the following process:
- Eliminative cleavage of the terminal β-D-mannosyl-(1→4)-β-D-glucuronosyl linkage of the side-chain of the polysaccharide xanthan, leaving a 4-deoxy-α-L-threo-hex-4-enuronosyl group at the terminus of the side-chain
It belongs to the family of lyases, specifically those carbon-oxygen lyases acting on polysaccharides. Xanthan lyase was first identified and partially purified in 1987.[1]
Xanthan is a polysaccharide secreted by several different bacterial taxa, such as the plant pathogen Xanthomonas campestris, and it consists of a main linear chain based on cellulose with side chains attached to alternate glucosyl (glucose) residues.[2] These side chains contain three monosaccharide residues. Xanthan lyase is produced by bacteria that degrade this polysaccharide, such as Bacillus, Corynebacterium, Bacteroides, Ruminococcaceae, and Paenibacillus species.[2][3][4]
Industrial applications
Xanthan is used in industry as a thickening agent in foods and drinks, as a stabilizing agent for foams, as a means of enhancing oil recovery and in the manufacture of good such as paints, cosmetics and explosives.[3] The use of xanthan lyase as a means of altering the physical properties of xanthans is an area of current research in biotechnology.
Structural studies
As of late 2007, 7 structures have been solved for this class of enzymes, with PDB accession codes 1J0M, 1J0N, 1X1H, 1X1I, 1X1J, 2E22, and 2E24. The enzyme from Bacillus is a monomer consisting of two domains: an alpha helical N-terminal domain, and a C-terminal domain composed of beta sheets.[5] The active site is a deep cleft located between these two domains.
References
- ↑ Sutherland IW (1987). "Xanthan lyases--novel enzymes found in various bacterial species". J. Gen. Microbiol. 133 (11): 3129–34. doi:10.1099/00221287-133-11-3129. PMID 3446747.
- ↑ 2.0 2.1 "Xanthan lyase of Bacillus sp. strain GL1 liberates pyruvylated mannose from xanthan side chains". Appl. Environ. Microbiol. 64 (10): 3765–8. 1 October 1998. doi:10.1128/AEM.64.10.3765-3768.1998. PMID 9758797.
- ↑ 3.0 3.1 "A pyruvated mannose-specific xanthan lyase involved in xanthan degradation by Paenibacillus alginolyticus XL-1". Appl. Environ. Microbiol. 65 (6): 2446–52. 1 June 1999. doi:10.1128/AEM.65.6.2446-2452.1999. PMID 10347025.
- ↑ Ostrowski, Matthew P.; La Rosa, Sabina Leanti; Kunath, Benoit J.; Robertson, Andrew; Pereira, Gabriel; Hagen, Live H.; Varghese, Neha J.; Qiu, Ling et al. (April 2022). "Mechanistic insights into consumption of the food additive xanthan gum by the human gut microbiota". Nature Microbiology 7 (4): 556–569. doi:10.1038/s41564-022-01093-0. PMID 35365790.
- ↑ "Crystal structure of Bacillus sp. GL1 xanthan lyase, which acts on the side chains of xanthan". J. Biol. Chem. 278 (9): 7663–73. 2003. doi:10.1074/jbc.M208100200. PMID 12475987. http://www.jbc.org/cgi/content/full/278/9/7663.
- Sutherland IW (1987). "Xanthan lyases--novel enzymes found in various bacterial species". J. Gen. Microbiol. 133 (11): 3129–34. doi:10.1099/00221287-133-11-3129. PMID 3446747.
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