Molecular and biochemical characterization of Ba-EGA, a cellulase secreted by Bacillus sp. AC-1 from Ampullaria crosseans.
A novel gene (Ba-ega) of Bacillus sp. AC-1, encoding an endoglucanase (Ba-EGA), was cloned and expressed in Escherichia coli. Ba-ega, containing a 1,980-bp open reading frame (ORF), encoded a protein of 659 amino acids and had a molecular mass of 74.87 kDa. Ba-EGA was a modular enzyme composed of a family-9 glycosyl hydrolase catalytic module (CM9) and a family-3 carbohydrate-binding module (CBM3). To investigate the functions of the CBM3 and CM9, a number of truncated derivatives of Ba-EGA were constructed, and all were active. The catalytic module (rCM9) alone was less stable at high temperature than the recombinant Ba-EGA (rBa-EGA). The temperature stability for the complex of rCM9 and rCBM3 was still lower than rBa-EGA, but higher than rCM9 alone. These observations indicated the existence of a non-covalent interaction between CM9 and CBM3 that might strengthen the stability of CM9. However, this interaction is not strong enough to mimic the protective effect of the CBM in the wild-type enzyme.
Zhang
Shuang
S
College of Life Science, Zhejiang Sci-Tech University, Hangzhou 310018, China.
Yin
Qiu-Yu
QY
Li
Yan-Hong
YH
Ding
Ming
M
Xu
Gen-Jun
GJ
Zhao
Fu-Kun
FK
D000595:Amino Acid Sequence; D000818:Animals; D001407:Bacillus / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D002480:Cellulase / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D005750:Gastric Juice / Q000382:microbiology; D049851:Gastropoda / Q000382:microbiology*; D008969:Molecular Sequence Data
D002480:Cellulase