Acidothermus celluloyticus xylanase

Abstract

A thermophilic endo-beta-1,4-xylanase derived from Acidothermus cellulolyticus is disclosed. The xylanase exhibits xylanase activity at an optimal temperature of 90° C. and an optimal pH range of about 4.5-6.0. The isolated xylanase is useful in the hydrolysis of lignocellulosic material.

1 . A recombinant endo-beta-1,4-xylanase comprising an amino acid sequence with at least 80% sequence identity to SEQ ID NO: 1. 
     
     
         2 . The xylanase of  claim 1 , wherein a region of the amino acid sequence of the recombinant endo-beta-1,4-xylanase conforms to consensus sequence: Pro-Xaa 1 -Pro-Xaa 2 -Pro (SEQ ID NO: 40), wherein Xaa 1  and Xaa 2  are each independently selected from the group consisting of: no amino acid, any 1 amino acid, any 2 amino acids, and any 3 amino acids. 
     
     
         3 . The xylanase of  claim 2 , wherein the amino acid sequence of the recombinant endo-beta-1,4-xylanase comprises a first Glu at a position corresponding to Glu-142 of SEQ ID NO: 1, and a second Glu at a position corresponding to Glu-259 of SEQ ID NO: 1, wherein the region of the amino acid sequence of the recombinant endo-beta-1,4-xylanase is located between the first Glu and the second Glu. 
     
     
         4 . The xylanase of  claim 2 , wherein Xaa 1  is one amino acid selected from the group consisting of: His, Lys, and Arg. 
     
     
         5 . The xylanase of  claim 2 , wherein Xaa 2  is one amino acid selected from the group consisting of: Leu, Ala, Val, Ile, Pro, Phe, Met, and Trp. 
     
     
         6 . The xylanase of  claim 2 , wherein the region of the amino acid sequence of the recombinant endo-beta-1,4-xylanase is Pro-His-Pro-Leu-Pro (SEQ ID NO: 27). 
     
     
         7 . The xylanase of  claim 1 , wherein the xylanase is active at pH values of about 3 to 9. 
     
     
         8 . The xylanase of  claim 1 , wherein the xylanase has a pH optimum of about 4.5 to 6.0. 
     
     
         9 . The xylanase of  claim 1 , wherein the xylanase has a molecular weight of about 40-48 kD. 
     
     
         10 . The xylanase of  claim 1 , wherein the xylanase is active at least from about 80-120° C. 
     
     
         11 . The xylanase of  claim 1 , wherein the xylanase has optimal activity at about 90° C. 
     
     
         12 . The xylanase of  claim 1 , wherein the xylanase retains at least 50% of initial activity, at 90° C., after incubation for at least 20 min at 90° C. 
     
     
         13 . The xylanase of  claim 1 , wherein the xylanase has a half-life of about 90 min at 90° C. in the presence of a xylan. 
     
     
         14 . The xylanase of  claim 13 , wherein the xylan is selected from the group consisting of: birchwood xylan, beech wood xylan, and oat spelt xylan. 
     
     
         15 . The xylanase of  claim 1 , further comprising a signal sequence peptide having amino acid sequence SEQ ID NO: 2. 
     
     
         16 . The xylanase of  claim 3 , wherein the first Glu is located within an amino acid region having a sequence of Asp-Val-Ala-Asn-Glu (SEQ ID NO: 25). 
     
     
         17 . The xylanase of  claim 3 , wherein the second Glu is located within an amino acid region having a sequence of Thr-Glu-Ala-Asp (SEQ ID NO: 26). 
     
     
         18 . The xylanase of  claim 1 , wherein the amino acid sequence of the recombinant endo-beta-1,4-xylanase has at least 95% sequence identity to SEQ ID NO: 1. 
     
     
         19 . The xylanase of  claim 1 , wherein the amino acid sequence of the recombinant endo-beta-1,4-xylanase is SEQ ID NO: 1. 
     
     
         20 . A recombinant cell comprising a nucleic acid molecule encoding the endo-beta-1,4-xylanase of  claim 1 . 
     
     
         21 . A method for hydrolyzing lignocellulose, the method comprising:
 contacting lignocellulose with a recombinant endo-beta-1,4-xylanase comprising an amino acid sequence with at least 80% sequence identity to SEQ ID NO: 1, wherein the lignocellulose is contacted with the recombinant xylanase at a temperature of at least 80° C. and a pH range from about 4.5-6.0.   
     
     
         22 . The method of  claim 21 , wherein the lignocellulose is contacted with the recombinant xylanase at a temperature of at least 90° C. 
     
     
         23 . The method of  claim 21 , wherein t the amino acid sequence of the recombinant endo-beta-1,4-xylanase is SEQ ID NO: 1. 
     
     
         24 . The method of  claim 21 , wherein a source of the lignocellulose is selected from the group consisting of: birchwood, oat spelt, switchgrass, corn stover, miscanthus, energy cane, sorghum, eucalyptus, willow, bagasse, hybrid poplar, short-rotation woody crop, conifer softwood, crop residue, yard waste, and a combination thereof. 
     
     
         25 . The method of  claim 21 , wherein the recombinant xylanase further comprises a signal sequence peptide having amino acid sequence SEQ ID NO: 2.