glycoside hydrolase family 55 (GH55) family domains and similar proteins; This family includes glycoside hydrolase family 55 (GH55) domains, which contains both endo- (EC 3.2.1.39) and exo-beta-1,3-glucanases (EC 3.2.1.58), based on the hydrolysis position. These enzymes hydrolyze beta-1,3-glucan bonds via inversion of stereochemistry at the anomeric carbon. GH55 is also called laminarinase due to its ability to hydrolyze laminarin, a beta-1,3-glucan with occasional beta-1,6 branching, found in brown algae such as Laminaria digitata. They have also been shown to react with the beta-1,3-glucans from fungal and plant cell walls. Also included in this family is SacteLam55A from the highly cellulolytic Streptomyces sp. SirexAA-E, a secreted protein encoded by SACTE_4363. Structural studies reveal an extended substrate-binding cleft with six or more subsites for sugar binding formed at the interface of two right handed beta-helical domains. Mutation studies support a critical glutamate as a catalytic acid and a proton relay network that activates water to serve as the catalytic base. Trichoderma harzianum and T. viride LamA1 have been characterized as endo-acting enzymes while Phanerochaete chrysosporium Lam55A, Chaetomium thermophilum CtLam55, as well as SacteLam55A, are exo-acting enzymes.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*....
gi 1153683942 230 ETYNITQsVINgnlitVDNFGAKGDGVTDDSAAFQAYCDSALTGQNLYLGAkGRYILKN 288
Cdd:cd23668   296 EDYPASQ-FVN-----VKDYGAKGDGVTDDTAALQAILNTAAGGKIVYFPA-GTYIVTD 347

fungal glycoside hydrolase family 55 (GH55) family domains and similar proteins; This family includes fungal glycoside hydrolase family 55 (GH55) proteins, which contains both endo- (EC 3.2.1.39) and exo-beta-1,3-glucanases (EC 3.2.1.58), based on the hydrolysis position. These enzymes hydrolyze beta-1,3-glucan bonds via inversion of stereochemistry at the anomeric carbon. GH55 is also called laminarinase due to its ability to hydrolyze laminarin, a beta-1,3-glucan with occasional beta-1,6 branching found in brown algae such as Laminaria digitata. They have also been shown to react with the beta-1,3-glucans from fungal and plant cell walls. Trichoderma harzianum BGN13.1 and T. viride LamA1 in this family have been characterized as endo-acting enzymes while Phanerochaete chrysosporium Lam55A and Chaetomium thermophilum CtLam55 are exo-acting enzymes. The CtLam55 substrate binding cleft exhibits restricted access on one side, thus rendering the enzyme as an exo-beta-1,3-glucanase; this has been confirmed by thin layer chromatography experiments. Also, a binding pocket was identified that could explain binding of branched laminarin and accumulation of laminaritriose. A similar binding pocket has been observed in T. chrysosporium Lam55A through structural studies and site-directed mutagenesis; both support a critical glutamate as a catalytic acid and a proton relay network that activates water to serve as the catalytic base.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*....
gi 1153683942 230 ETYNITQsVINgnlitVDNFGAKGDGVTDDSAAFQAYCDSALTGQNLYLGAkGRYILKN 288
Cdd:cd23668   296 EDYPASQ-FVN-----VKDYGAKGDGVTDDTAALQAILNTAAGGKIVYFPA-GTYIVTD 347

fungal glycoside hydrolase family 55 (GH55) family domains and similar proteins; This family includes fungal glycoside hydrolase family 55 (GH55) proteins, which contains both endo- (EC 3.2.1.39) and exo-beta-1,3-glucanases (EC 3.2.1.58), based on the hydrolysis position. These enzymes hydrolyze beta-1,3-glucan bonds via inversion of stereochemistry at the anomeric carbon. GH55 is also called laminarinase due to its ability to hydrolyze laminarin, a beta-1,3-glucan with occasional beta-1,6 branching found in brown algae such as Laminaria digitata. They have also been shown to react with the beta-1,3-glucans from fungal and plant cell walls. Trichoderma harzianum BGN13.1 and T. viride LamA1 in this family have been characterized as endo-acting enzymes while Phanerochaete chrysosporium Lam55A and Chaetomium thermophilum CtLam55 are exo-acting enzymes. The CtLam55 substrate binding cleft exhibits restricted access on one side, thus rendering the enzyme as an exo-beta-1,3-glucanase; this has been confirmed by thin layer chromatography experiments. Also, a binding pocket was identified that could explain binding of branched laminarin and accumulation of laminaritriose. A similar binding pocket has been observed in T. chrysosporium Lam55A through structural studies and site-directed mutagenesis; both support a critical glutamate as a catalytic acid and a proton relay network that activates water to serve as the catalytic base.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*....
gi 1153683942 230 ETYNITQsVINgnlitVDNFGAKGDGVTDDSAAFQAYCDSALTGQNLYLGAkGRYILKN 288
Cdd:cd23668   296 EDYPASQ-FVN-----VKDYGAKGDGVTDDTAALQAILNTAAGGKIVYFPA-GTYIVTD 347

fungal glycoside hydrolase family 55 (GH55) family domains and similar proteins; This family includes fungal glycoside hydrolase family 55 (GH55) proteins, which contains both endo- (EC 3.2.1.39) and exo-beta-1,3-glucanases (EC 3.2.1.58), based on the hydrolysis position. These enzymes hydrolyze beta-1,3-glucan bonds via inversion of stereochemistry at the anomeric carbon. GH55 is also called laminarinase due to its ability to hydrolyze laminarin, a beta-1,3-glucan with occasional beta-1,6 branching found in brown algae such as Laminaria digitata. They have also been shown to react with the beta-1,3-glucans from fungal and plant cell walls. Trichoderma harzianum BGN13.1 and T. viride LamA1 in this family have been characterized as endo-acting enzymes while Phanerochaete chrysosporium Lam55A and Chaetomium thermophilum CtLam55 are exo-acting enzymes. The CtLam55 substrate binding cleft exhibits restricted access on one side, thus rendering the enzyme as an exo-beta-1,3-glucanase; this has been confirmed by thin layer chromatography experiments. Also, a binding pocket was identified that could explain binding of branched laminarin and accumulation of laminaritriose. A similar binding pocket has been observed in T. chrysosporium Lam55A through structural studies and site-directed mutagenesis; both support a critical glutamate as a catalytic acid and a proton relay network that activates water to serve as the catalytic base.

                          10        20
                  ....*....|....*....|
gi 1153683942 246 VDNFGAKGDGVTDDSAAFQA 265
Cdd:cd23668    26 VKDYGAKGDGVTDDTAAINA 45