title: Expression, characterization and synergistic interactions of Myxobacter Sp. AL-1 Cel9 and Cel48 glycosyl hydrolases.
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 His(6)-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.
authors.affiliation: Instituto de Investigación en Biología Experimental (IIBE), Facultad de Química, Universidad de Guanajuato, P.O. Box 187, Guanajuato, Gto. 36050, Mexico.
authors.forename: Norma
authors.initials: N
authors.lastname: Ramírez-Ramírez
authors.affiliation: Instituto de Investigación en Biología Experimental (IIBE), Facultad de Química, Universidad de Guanajuato, P.O. Box 187, Guanajuato, Gto. 36050, Mexico.
authors.forename: Eliel R
authors.initials: ER
authors.lastname: Romero-García
authors.affiliation: Instituto de Investigación en Biología Experimental (IIBE), Facultad de Química, Universidad de Guanajuato, P.O. Box 187, Guanajuato, Gto. 36050, Mexico.
authors.forename: Vianney C
authors.initials: VC
authors.lastname: Calderón
authors.affiliation: Instituto de Investigación en Biología Experimental (IIBE), Facultad de Química, Universidad de Guanajuato, P.O. Box 187, Guanajuato, Gto. 36050, Mexico.
authors.forename: Claudia I
authors.initials: CI
authors.lastname: Avitia
authors.affiliation: Instituto de Ciencias de la Salud, Universidad Autónoma del Estado de Hidalgo, Abasolo 600, Pachuca, Hgo 42000, Mexico.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Téllez-Valencia
authors.affiliation: Instituto de Investigación en Biología Experimental (IIBE), Facultad de Química, Universidad de Guanajuato, P.O. Box 187, Guanajuato, Gto. 36050, Mexico.
authors.forename: Mario
authors.initials: M
authors.lastname: Pedraza-Reyes