Diverse dextranase genes from Paenibacillus species

Abstract

Genes encoding dextranolytic enzymes were isolated from Paenibacillus strains Dex40-8 and Dex50-2. Single, similar but non-identical dex1 genes were isolated from each strain, and a more divergent dex2 gene was isolated from strain Dex50-2. The protein deduced from the Dex40-8 dex1 gene sequence had 716 amino acids, with a predicted M(r) of 80.8 kDa. The proteins deduced from the Dex50-2 dex1 and dex2 gene sequences had 905 and 596 amino acids, with predicted M(r) of 100.1 kDa and 68.3 kDa, respectively. The deduced amino acid sequences of all three dextranolytic proteins had similarity to family 66 glycosyl hydrolases and were predicted to possess cleavable N-terminal signal peptides. Homology searches suggest that the Dex40-8 and Dex50-2 Dex1 proteins have one and two copies, respectively, of a carbohydrate-binding module similar to CBM_4_9 (pfam02018.11). The Dex50-2 Dex2 deduced amino acid sequence had highest sequence similarity to thermotolerant dextranases from thermophilic Paenibacillus strains, while the Dex40-8 and Dex50-2 Dex1 deduced protein sequences formed a distinct sequence clade among the family 66 proteins. Examination of seven Paenibacillus strains, using a polymerase chain reaction-based assay, indicated that multiple family 66 genes are common within this genus. The three recombinant proteins expressed in Escherichia coli possessed dextranolytic activity and were able to convert ethanol-insoluble blue dextran into an ethanol-soluble product, indicating they are endodextranases (EC 3.2.1.11). The reaction catalysed by each enzyme had a distinct temperature and pH dependence.

Truncation of N- and C-terminal regions of Streptococcus mutans dextranase enhances catalytic activity

“…Similar observations were also reported on recombinant Dex of Streptococcus mutans Ingbritt (four isoforms) (Igarashi et al 1995a), Streptococcus salivarius (three isoforms) (Lawman and Bleiseis 1991) or Streptococcus downei (several isoforms) (Igarashi et al 2001). Finnegan et al (2004aFinnegan et al ( , 2004bFinnegan et al ( , 2005 isolated 11 strains of Paenibacillus, all of which secreted 2-5…”

Carbohydrate Binding Modules: Biochemical Properties and Novel Applications

“…CBMs have been recognized in esterase from Penicillium funiculosum (108), isomaltodextranase from Arthrobacter globiformis (82), arabinofuranosidases from Aspergillus kawachii and Cellvibrio japonicus (21,136), pectate lyase from Pseudomonas cellulose (27), ␤-agarase from the marine bacterium JAMB-A94 (145), ␤-glucosidase from Phanerochaete chrysosporium (127), and dextranase from Paenibacillus sp. (59). An interesting observation was recently reported when a CBM was found in cytochrome (217).…”

Bacteroides thetaiotaomicron VPI‐5482 glycoside hydrolase family 66 homolog catalyzes dextranolytic and cyclization reactions

“…The BtDex amino acid sequence exhibited 30-44% identity with five thermostable Paenibacillus sp. endodextranases [11,12], 29% identity with Bacillus circulans T-3040 CITase [2], 24% identity with PsDex [9], and 24% with Streptococcus sp. endo-dextranases [13][14][15] (Fig.…”