[The properties of four C-terminal carbohydrate-binding modules (CBM4) of laminarinase Lic16A of Clostridium thermocellum].
At the C-terminus of multimodular laminarinase Lic16A Clostridium thermocellum four carbohydrate-binding modules (CBM), belonging to family 4, were found. The isolated CBM - CBM4_1, CBM4_2, CBM4_3, CBM4_4 and the tandem CBM4_(1-4) were obtained. None of the recombinant proteins did have the affinity to soluble beta-1,3-1,4-glucans--laminarin and lihenan--the main specific substrates of Licl6A. All modules, except CBM4_4, had the ability to bind bacterial crystalline cellulose, that was atypical for the family 4 CBMs. We found that all CBMs 4 of Licl6A had affinity for xylan, chitin, beta-glucan from yeast cell wall and Avicel, while CBM4_3 and CBM4_4 had additional affinity to chitosan. The tandem CBM4_(1-4) had the highest affinity to yeast cell wall beta-glucan, avicel and pustulan. The binding constants for these substrates were about 100 times higher than that of the individual modules, suggesting a synergy in the process of absorption to these polysaccharides. This finding helps to explain the evolutionary process of CBM multiplication.
I A
IA
Dvortsov
N A
NA
Lunina
V V
VV
Zverlov
G A
GA
Velikodvorskaia
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D044602:Cellulases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D048013:Acetivibrio thermocellus / Q000201:enzymology* / Q000235:genetics; D019143:Evolution, Molecular; D011134:Polysaccharides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity / Q000502:physiology
D001426:Bacterial Proteins; D011134:Polysaccharides; D044602:Cellulases