Enzymatic mechanism for arabinan degradation and transport in the thermophilic bacterium Caldanaerobius polysaccharolyticus.

Enzymatic mechanism for arabinan degradation and transport in the thermophilic bacterium Caldanaerobius polysaccharolyticus. Appl Environ Microbiol. 2017 Jul 14;: Authors: Wefers D, Dong J, Abdel-Hamid AM, Müller Paul H, Pereira GV, Han Y, Dodd D, Baskaran R, Mayer B, Mackie RI, Cann I Abstract The plant cell wall polysaccharide arabinan is an important supply of arabinose, and unraveling arabinan degrading strategies by microbes is important for understanding its use as a source of energy. Here, we explored the arabinan degrading enzymes in the thermophilic bacterium Caldanaerobius polysaccharolyticus and identified a gene cluster encoding two glycoside hydrolase (GH) family 51 α-L-arabinofuranosidases (CpAbf51A, CpAbf51B), a GH43 endo-arabinanase (CpAbn43A), a GH27 β-L-arabinopyranosidase (CpAbp27A), and two GH127 β-L-arabinofuranosidases (CpAbf127A, CpAbf127B). The genes were expressed as recombinant proteins, and the functions of the purified proteins were determined with pNP-linked sugars and naturally occurring pectin structural elements as substrates. The results demonstrated that CpAbn43A is an endo-arabinanase, while CpAbf51A and CpAbf51B are α-L-arabinofuranosidases that exhibit diverse substrate specificities, cleaving α-1,2-, α-1,3-, and α-1,5-linkages of purified arabinan-oligosaccharides. Furthermore, both CpAbf127A and CpAbf127B cleaved β-arabinofuranose residues in complex arabinan side chains, thus providing...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research