Patent ID: 8114974

Claim:
An isolated nucleic acid comprising a polynucleotide coding sequence that encodes a chimeric polypeptide possessing a xylose to xylulose xylose isomerase activity, wherein the polynucleotide coding sequence consists of, in 5′-to-3′ orientation, a first polynucleotide encoding five or more contiguous amino acids of a fungal xylose isomerase and a second polynucleotide encoding five or more contiguous amino acids of a Ruminococcus flavefaciens strain xylose isomerase, and wherein, optionally, the second polynucleotide has one or more point mutations that result in one or more amino acid substitutions in the amino acid sequence of a Ruminococcus flavefaciens strain xylose isomerase at positions that correspond to positions in the amino acid sequence of SEQ ID NO:31 selected from the group consisting of 3, 5, 6, 42, 45, 46, 51, 52, 53, 54, 56, 58, 64, 85, 101, 107, 121, 131, 136, 137, 140, 141, 147, 179, 180, 181, 184, 203, 204, 205, 208, 209, 210, 211, 214, 215, 252, 253, 254, 255, 257, 273, 277, 292, 296, 299, 300, 301, 344, 345, 346, 372, 373, 374, and 375.