A glycoside hydrolase family 5 β-mannanase-encoding gene was cloned from Bacillus sp. HJ14 isolated from saline soil in Heijing town. Coding sequence of mature protein (without the predicted signal peptide from M1 to A30) was successfully expressed in Escherichia coli BL21 (DE3). Purified recombinant mannanase (rMan5HJ14) exhibited optimal activity at pH 6.5 and 65 °C. The enzyme showed good salt tolerance, retaining more than 56 % β-mannanase activity at 3.0-30.0 % (w/v) NaCl and more than 94 % of the initial activity after incubation with 3.0-30.0 % (w/v) NaCl at 37 °C for 60 min. Almost no mannanase activity was lost after incubation of rMan5HJ14 with trypsin, proteinase K, and Alcalase at 37 °C for 60 min. Surfactants and chelating agents, namely SDS, CTAB, Tween 80, Triton X-100, EDTA, and sodium tripolyphosphate, showed little or no effect (retaining >82.4 % activity) on enzymatic activity. Liquid detergents, namely Tupperware, Walch, Bluemoon, Tide, and OMO, also showed little or no effect (retaining >72.4 % activity) on enzymatic activity at 0.5-2.0 % (v/v). The enzyme further presents a high proportion (11.97 %) of acidic amino acid residues (D and E), which may affect the SDS and NaCl tolerance of the enzyme. Together, the mannanase may be an alternative for potential use in liquid detergent industry.

• MeSH
• aktivace enzymů účinky léků   MeSH
• Bacillus účinky léků   genetika   metabolismus   MeSH
• beta-mannosidasa chemie   genetika   izolace a purifikace   metabolismus   MeSH
• chlorid sodný farmakologie   MeSH
• detergenty farmakologie   MeSH
• endopeptidasy metabolismus   MeSH
• exprese genu MeSH
• genom bakteriální MeSH
• hydrolýza MeSH
• ionty MeSH
• kovy MeSH
• povrchově aktivní látky farmakologie   MeSH
• rekombinantní proteiny MeSH
• sekvence aminokyselin MeSH
• sekvenční analýza DNA MeSH
• stabilita enzymů účinky léků   MeSH
• tolerance k soli * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

A mannanase-coding gene was cloned from Sphingobacterium sp. GN25 isolated from the feces of Grus nigricollis. The gene encodes a 371-residue polypeptide (ManAGN25) showing less than 74 % identity with a number of hypothetical proteins and putative glucanases and mannanases. Before experiment's performance, ManAGN25 was predicted to be a low-temperature active mannanase based on the molecular characterization, including (1) ManAGN25 shared the highest identity of 41.1 % with the experimentally verified low-temperature active mannanase (ManAJB13) from Sphingomonas sp. JB13; (2) compared with their mesophilic and thermophilic counterparts, ManAGN25 and ManAJB13 had increased number of amino acid residues around their catalytic sites; (3) these increased number of amino acid residues built longer loops, more α-helices, and larger total accessible surface area and packing volume. Then the experiments of biochemical characterization verified that the purified recombinant ManAGN25 is a low-temperature active mannanase: the enzyme showed apparently optimal activity at 35-40 °C and retained 78.2, 44.8, and 15.0 % of its maximum activity when assayed at 30, 20, and 10 °C, respectively; the half-life of the enzyme was approximately 60 min at 37 °C; the enzyme presented a K m of 4.2 mg/ml and a k cat of 0.4/s in McIlvaine buffer (pH 7.0) at 35 °C using locust bean gum as the substrate; and the activation energy for hydrolysis of locust bean gum by the enzyme was 36.0 kJ/mol. This study is the first to report the molecular and biochemical characterizations of a mannanase from a strain.

• MeSH
• bakteriální proteiny chemie   genetika   izolace a purifikace   metabolismus   MeSH
• beta-mannosidasa chemie   genetika   izolace a purifikace   metabolismus   MeSH
• kinetika MeSH
• konformace proteinů MeSH
• molekulární sekvence - údaje MeSH
• nízká teplota MeSH
• sekvence aminokyselin MeSH
• sekvenční seřazení MeSH
• Sphingobacterium chemie   enzymologie   genetika   MeSH
• stabilita enzymů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

This study is focused on the analysis and mutagenesis of β-mannosidase from Bacteroides thetaiotaomicron with the aim of broadening its substrate specificity to 2-acetamido-2-deoxy-β-d-mannopyranosyl (β-ManNAc) derivatives. Various conformations ((4)C1, (4)H5 and (1)S5) of native and modified ligands were docked to the binding site of the protein to determine the most suitable conformation of sugars for further hydrolysis. Key amino acid residues were mutated in silico focusing on stabilizing the acetamido group of β-ManNAc as well as forming the oxazoline intermediate needed for hydrolysis. The results of large set of 5 ns molecular dynamic simulations showed that the majority of the active site residues are involved in substrate interaction and do not exhibit a higher flexibility except for Asn178. Mutations of Asn178 to alanine and Asp199 to serine could lead to a stabilization of the acetamido group in the binding site. So far, in vitro mutagenesis and the screen of a large variety of biological sources were unable to extend β-mannosidase's activity to include β-ManNAc derivatives.

• MeSH
• Bacteroides enzymologie   MeSH
• beta-mannosidasa chemie   genetika   metabolismus   MeSH
• biokatalýza * MeSH
• proteinové inženýrství * MeSH
• simulace molekulární dynamiky MeSH
• simulace molekulového dockingu MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

β-Mannosidase (EC 3.2.1.25) is an important exoglycosidase specific for the hydrolysis of terminal β-linked mannoside in various oligomeric saccharide structures. β-Mannosidase from Aspergillus niger was expressed in Pichia pastoris and purified to clear homogeneity. β-Mannosidase was crystallized in the presence of D-mannose and the crystal diffracted to 2.41 Å resolution. The crystal belonged to space group P1, with unit-cell parameters a=62.37, b=69.73, c=69.90 Å, α=108.20, β=101.51, γ=103.20°. The parameters derived from the data collection indicate the presence of one molecule in the asymmetric unit.

• MeSH
• Aspergillus niger chemie   enzymologie   MeSH
• beta-mannosidasa chemie   genetika   MeSH
• fungální proteiny chemie   genetika   MeSH
• krystalizace MeSH
• krystalografie rentgenová MeSH
• mannosa chemie   MeSH
• Pichia chemie   genetika   MeSH
• rekombinantní proteiny chemie   genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

β-Mannosidase (EC 3.2.1.25) is an exoglycosidase specific for the hydrolysis of terminal β-linked mannoside in various sugar chains. cDNA corresponding to the β-mannosidase gene was cloned from Aspergillus niger, sequenced, and expressed in the yeast Pichia pastoris. The β-mannosidase gene contains an open reading frame which encodes the protein with 933 amino acid residues. The wild type and recombinant proteins were purified to apparent homogeneity and biochemically characterized (K(M) 0.28 and 0.44 mmol/l for p-nitrophenyl β-d-mannopyranoside, pI 4.2 and 4.0, and their pH optima were at pH 4.5 and 5.5 and 65°C, respectively).

• MeSH
• Aspergillus niger enzymologie   genetika   MeSH
• beta-mannosidasa biosyntéza   chemie   genetika   izolace a purifikace   MeSH
• elektroforéza v polyakrylamidovém gelu MeSH
• fungální proteiny biosyntéza   chemie   genetika   izolace a purifikace   MeSH
• klonování DNA MeSH
• koncentrace vodíkových iontů MeSH
• kultivační média MeSH
• Pichia enzymologie   genetika   MeSH
• rekombinantní proteiny biosyntéza   chemie   genetika   izolace a purifikace   MeSH
• stabilita enzymů MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH