Structural and Functional Insights Into CmGH1, a Novel GH39 Family β-Glucosidase From Deep-Sea Bacterium

Abstract

Glucosidases play key roles in many diseases and are limiting enzymes during cellulose degradation, which is an important part of global carbon cycle. Here, we identified a novel β-glucosidase, CmGH1, isolated from marine bacterium Croceicoccus marinus E4A9 T . In spite of its high sequence and structural similarity with β-xylosidase family members, CmGH1 had enzymatic activity toward p-nitrophenyl-β-D-glucopyranoside (p-NPG) and cellobiose. The K m and K cat values of CmGH1 toward p-NPG were 0.332 ± 0.038 mM and 2.15 ± 0.081 min −1 , respectively. CmGH1 was tolerant to high concentration salts, detergents, as well as many kinds of organic solvents. The crystal structure of CmGH1 was resolved with a 1.8 Å resolution, which showed that CmGH1 was composed of a canonical (α/β) 8 -barrel catalytic domain and an auxiliary β-sandwich domain. Although no canonical catalytic triad residues were found in CmGH1, structural comparison and mutagenesis analysis suggested that residues Gln157 and Tyr264 of CmGH1 were the active sites. Mutant Q157E significantly increased its hydrolase activity up to 15-fold, whereas Y264E totally abolished its enzymatic activity. These results might provide new insights into understanding the different catalytic mechanism during evolution for β-glucosidases and β-xylosidases.

Enhanced Biomass Yield of and Saccharification in Transgenic Tobacco Over-Expressing β-Glucosidase

“…html) and catalyze the hydrolysis of the β-glucosidic bond between two carbohydrate moieties, or between a carbohydrate and an aglucone moiety. In plants, β-glucosidases play important roles in growth and development, including the (1) release of active forms of phytohormones from their inactivated forms (conjugated-phytohormones), (2) formation of intermediates in cell wall lignification, (3) degradation of cell wall of the endosperm during germination, and (4) activation of chemical defense compounds [9][10][11][12]. Recently, β-glucosidases have garnered attention owing to their biotechnological and industrial applications.…”

Structure and Function Insight of the α-Glucosidase QsGH13 From Qipengyuania seohaensis sp. SW-135

“…The recombinant E. coli BL21(DE3) plus/pSMT3- qsgh13 was cultured in LB medium containing 50 μg/ml of kanamycin and 34 μg/ml of chloramphenicol at 37°C. When the OD 600 reached 0.8, the recombinant protein expression was induced by 0.5 mM isopropyl-β-D-thiogalactopyranoside (IPTG) for 20 h at 16°C ( Shen et al, 2019 ). Cells were harvested by centrifugation at 5,000 rpm for 15 min at 4°C.…”

“…The recombinant E. coli BL21(DE3) plus/pSMT3-qsgh13 was cultured in LB medium containing 50 µg/ml of kanamycin and 34 µg/ml of chloramphenicol at 37 • C. When the OD 600 reached 0.8, the recombinant protein expression was induced by 0.5 mM isopropyl-β-D-thiogalactopyranoside (IPTG) for 20 h at 16 • C (Shen et al, 2019). Cells were harvested by centrifugation at 5,000 rpm for 15 min at 4 • C. The cell precipitation was resuspended in a lysis buffer [50 mM Tris, pH 8.0; 500 mM NaCl; 1% (v/v) glycerol; 10 mM imidazole; 1 mM β-Me; 0.2 mM PMSF] and was disrupted on ice with an ultrasonic crusher (SCIENIZ, Ningbo, China).…”

Croceicoccus hydrothermalis sp. nov., isolated from shallow-sea hydrothermal system off Kueishantao Island

“…At the time of writing, the natural habitats of eight species with validly published species names in the genus Croceicoccus were all marine environments, such as coastal sediment, deep sea sediment, sea water and marine biofilm [1, 2, 4–7]. Strains of members of the genus Croceicoccus have been reported to produce esterase [8], carotenoids [9] and β-xylosidase [10]. Ubiquinone 10 is the predominant respiratory quinone of the members of the genus Croceicoccus [2–7].…”