Abstract: The soil microorganism Myxobacter Sp. AL-1 regulates in a differential manner the production of five extracellular cellulases during its life cycle. The nucleotide sequence of a cel9-cel48 cluster from the genome of this microorganism was recently obtained. Cel48 was expressed in Escherichia coli to generate a His6-Cel48 protein and the biochemical properties of the pure protein were determined. Cel48 was more efficient in degrading acid-swollen avicel (ASC) than carboxymethylcellulose (CMC). On the other hand, cel9 was expressed in Bacillus subtilis from an IPTG-inducible promoter. Zymogram analysis showed that after IPTG-induction, Cel9 existed in both the cell fraction and the culture medium of B. subtilis and the secreted protein was purified to homogeneity by FPLC-ionic exchange chromatography. The exocellobiohydrolase Cel48 showed a synergism of 1.68 times with the endocellulase Cel9 during ASC degradation using an 8.1- fold excess of Cel48 over Cel9. Western blot analysis revealed that both proteins were synthesized and secreted to the culture medium of Myxobacter Sp. AL-1. These results show that the cel9-cel48 cluster encodes functional endo- and exo-acting cellulases that allows Myobacter Sp. AL-1 to hydrolyse cellulose.
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Ramírez-Ramírez, N.; Romero-García, E.R.; Calderón, V.C.; Avitia, C.I.; Téllez-Valencia, A.; Pedraza-Reyes, M. Expression, Characterization and Synergistic Interactions of Myxobacter Sp. AL-1 Cel9 and Cel48 Glycosyl Hydrolases. Int. J. Mol. Sci. 2008, 9, 247-257.
Ramírez-Ramírez N, Romero-García ER, Calderón VC, Avitia CI, Téllez-Valencia A, Pedraza-Reyes M. Expression, Characterization and Synergistic Interactions of Myxobacter Sp. AL-1 Cel9 and Cel48 Glycosyl Hydrolases. International Journal of Molecular Sciences. 2008; 9(3):247-257.
Ramírez-Ramírez, Norma; Romero-García, Eliel R.; Calderón, Vianney C.; Avitia, Claudia I.; Téllez-Valencia, Alfredo; Pedraza-Reyes, Mario. 2008. "Expression, Characterization and Synergistic Interactions of Myxobacter Sp. AL-1 Cel9 and Cel48 Glycosyl Hydrolases." Int. J. Mol. Sci. 9, no. 3: 247-257.