Evidence that the xylanase activity from Sulfolobus solfataricus Oalpha is encoded by the endoglucanase precursor gene (sso1354) and characterization of the associated cellulase activity.
Sulfolobus solfataricus strain Oalpha was previously isolated for its ability to grow on minimal medium supplemented with xylan as a carbon source. The strain exhibited thermostable xylanase activity but several attempts to identify the gene encoding for the activity failed. Further studies showed that the xylanase displayed activity on carboxymethylcellulose (CMC) and the new activity was characterized. It exhibited an optimal temperature and pH of 95 degrees C and 3.5, respectively, and a half-life of 53 min at 95 degrees C. The enzyme, which was demonstrated to be glycosylated, hydrolyzed CMC in an endo-manner releasing cellobiose and other cello-oligomers. Analysis of the tryptic fragments by tandem mass spectrometry led to identification of the endoglucanase precursor, encoded by the sso1354 gene, as the protein possessing dual activity. The efficiency of the SSO1354 protein in degrading cellulosic and hemicellulosic fractions contained in agronomic residues was tested at low pH and high temperature. Cellulose and xylan were degraded to glucose and xylose at 90 degrees C, pH 4 by an enzyme mix consisting of SSO1354 and additional glycosyl hydrolases from S. solfataricus Oalpha. Given its role in saccharification processes requiring high temperatures and acidic environments, SSO1354 represents an interesting candidate for the utilization of agro-industrial waste for fuel production.
Istituto di Biochimica delle Proteine, Consiglio Nazionale delle Ricerche, via Pietro Castellino 111, 80131 Naples, Italy.
Luisa
L
Maurelli
Alfonso
A
Giovane
Alessandra
A
Esposito
Marco
M
Moracci
Immacolata
I
Fiume
Mosè
M
Rossi
Alessandra
A
Morana
D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000235:genetics* / Q000378:metabolism; D002266:Carboxymethylcellulose Sodium / Q000378:metabolism; D002480:Cellulase / Q000235:genetics* / Q000378:metabolism; D002850:Chromatography, Gel; D017124:Conserved Sequence; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D048229:Sulfolobus solfataricus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D013816:Thermodynamics
D019843:Archaeal Proteins; D008565:Membrane Proteins; D010446:Peptide Fragments; D002480:Cellulase; D043364:Endo-1,4-beta Xylanases; D002266:Carboxymethylcellulose Sodium