Revisiting the Cellulosimicrobium cellulons yeast-lytic β-1, 3-glucanases toolbox: A review

Cellulosimicrobium cellulans (also known with the synonyms Cellulomonas cellulans, Oerskovia xanthineolytica, and Arthrobacter luteus) is an actinomycete that excretes yeast cell wall lytic enzyme complexes containing endo-β-1,3-glucanases [EC 3.2.1.39 and 13.2.1.6] as key constituents. Three genes encoding endo-β-1,3-glucanases from two C. cellulans strains have been cloned and characterised over the past years. The βgIII and βIIIA genes from strain DSM 10297 (also known as O. xanthineolytica LL G109) encoded proteins of 40.8 and 28.6 kDa, respectively, whereas the β-1,-3glucanase gene from strain ATCC 21606 (also known as A. luteus 73-14) encoded a 54.5 kDa protein. Alignment of their deduced amino acid sequences reveal that βgIIIA and βgIIIA have catalytic domains assigned to family 16 of glycosyl hydrolases, whereas the catalytic domain from the 54.5 kDa glucanase belongs to family 64. Notably, both βgIII and the 54.5 kDa β-1,3-glucanase are multidomain proteins, having a lectin-like C-terminal domain that has been assigned to family 13 of carbohydrate binding modules, and that confers to β-1,3-glucanases the ability to lyse viable yeast cells. Furthermore, βgIII may also undergo posttranslational proteolytic processing of its C-terminal domain, resulting in a truncated enzyme retaining its glucanase activity but with very low yeast-lytic activity. In this review, the diversity in terms of structural and functional characteristics of the C. cellulans β-1,3-glucanases has been compiled and compared. © 2006 Ferrer; licensee BioMed Central Ltd.