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Structure and expression of an amylopullulanase gene from Bacillus stearothermophilus TS‐23
Author(s) -
Chen JenTao,
Chen MingChu,
Chen LiLin,
Chu WenShen
Publication year - 2001
Publication title -
biotechnology and applied biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.468
H-Index - 70
eISSN - 1470-8744
pISSN - 0885-4513
DOI - 10.1042/ba20010003
Subject(s) - homology (biology) , thermophile , biology , escherichia coli , geobacillus stearothermophilus , open reading frame , peptide sequence , gene , nucleic acid sequence , bacillaceae , biochemistry , amino acid , microbiology and biotechnology , enzyme , bacteria , genetics , bacillus subtilis
An amylopullulanase gene ( apu TS) from Bacillus stearothermophilus TS‐23 was cloned and characterized. apu TS consisted of an open reading frame of 6054 bp encoding a protein of 2018 amino acids with a calculated M r of 223811. The deduced amino acid sequence revealed four highly conserved regions that are common among amylolytic enzymes. In the C‐terminal region, a six‐amino‐acid sequence (Pro‐Gly‐Ser‐Gly‐Thr‐Thr) is repeated nine times. It shared the highest degree of homology with the amylopullulanase of Bacillus sp. XAL601. The enzyme also had moderate homology with amylopullulanases from thermophilic anaerobic bacteria. Low levels of homology were observed between the ApuTS of B. stearothermophilus TS‐23 and amylopullulanases of Pyrococcus abyssi Orsay, P. furiosus and Bacillus sp. KSM1378. When the intact coding region of apu TS was expressed in Escherichia coli under the control of the lac promoter, the product was degenerate, as revealed by amylase activity staining after SDS/PAGE. The largest active polypeptide had an M r of about 220000, while the smallest one had an M r of about 105000. Upstream of the apu TS gene, a gene orf X was fortuitously cloned. The putative OrfX protein was weakly related to the myosin heavy chain. It was predicted to contain a central, 179‐residue‐long, coiled‐coil domain.