alpha-beta barrel catalytic domain of agarase, such as GH86-like endo-acting agarases identified in non-marine organisms
Typically, agarases (E.C. 188.8.131.52) are found in ocean-dwelling bacteria since agarose is a principle component of red algae cell wall polysaccharides. Agarose is a linear polymer of alternating D-galactose and 3,6-anhydro-L-galactopyranose. Endo-acting agarases, such as glycoside hydrolase 16 (GH16) and GH86 hydrolyze internal beta-1,4 linkages. GH86-like endo-acting agarase of this protein family has been identified in the human intestinal bacterium Bacteroides uniformis. This acquired metabolic pathway, as demonstrated by the prevalence of agar-specific genetic cluster called polysaccharide utilization loci (PULs), varies considerably between human populations, being much more prevalent in a Japanese sample than in North America, European, or Chinese samples. Agarase activity was also identified in the non-marine bacterium Cellvibrio sp.