In:
Applied and Environmental Microbiology, American Society for Microbiology, Vol. 66, No. 2 ( 2000-02), p. 664-670
Abstract:
Genomic walking PCR was used to obtained a 4,567-bp nucleotide sequence from Caldibacillus cellulovorans . Analysis of this sequence revealed that there were three open reading frames, designated ORF1, ORF2, and ORF3. Incomplete ORF1 encoded a putative C-terminal cellulose-binding domain (CBD) homologous to members of CBD family IIIb, while putative ORF3 encoded a protein of unknown function. The putative ManA protein encoded by complete manA ORF2 was an enzyme with a novel multidomain structure and was composed of four domains in the following order: a putative N-terminal domain (D1) of unknown function, an internal CBD (D2), a β-mannanase catalytic domain (D3), and a C-terminal CBD (D4). All four domains were linked via proline-threonine-rich peptides. Both of the CBDs exhibited sequence similarity to family IIIb CBDs, while the mannanase catalytic domain exhibited homology to the family 5 glycosyl hydrolases. The purified recombinant enzyme ManAd3 expressed from the cloned catalytic domain (D3) exhibited optimum activity at 85°C and pH 6.0 and was extremely thermostable at 70°C. This enzyme exhibited high specificity with the substituted galactomannan locust bean gum, while more substituted galacto- and glucomannans were poorly hydrolyzed. Preliminary studies to determine the effect of the recombinant ManAd3 and a recombinant thermostable β-xylanase on oxygen-delignified Pinus radiata kraft pulp revealed that there was an increase in the brightness of the bleached pulp.
Type of Medium:
Online Resource
ISSN:
0099-2240
,
1098-5336
DOI:
10.1128/AEM.66.2.664-670.2000
Language:
English
Publisher:
American Society for Microbiology
Publication Date:
2000
detail.hit.zdb_id:
223011-2
detail.hit.zdb_id:
1478346-0
SSG:
12
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