Cloning and sequence analysis of genes encoding xylanases and acetyl xylan esterase from Streptomyces thermoviolaceus OPC-520.
Three genes encoding two types of xylanases (STX-I and STX-II) and an acetyl xylan esterase (STX-III) from Streptomyces thermoviolaceus OPC-520 were cloned, and their DNA sequences were determined. The nucleotide sequences showed that genes stx-II and stx-III were clustered on the genome. The stx-I, stx-II, and stx-III genes encoded deduced proteins of 51, 35.2, and 34.3 kDa, respectively. STX-I and STX-II bound to both insoluble xylan and crystalline cellulose (Avicel). Alignment of the deduced amino acid sequences encoded by stx-I, stx-II, and stx-III demonstrated that the three enzymes contain two functional domains, a catalytic domain and a substrate-binding domain. The catalytic domains of STX-I and STX-II showed high sequence homology to several xylanases which belong to families F and G, respectively, and that of STX-III showed striking homology with an acetyl xylan esterase from S. lividans, nodulation proteins of Rhizobium sp., and chitin deacetylase of Mucor rouxii. In the C-terminal region of STX-I, there were three reiterated amino acid sequences starting from C-L-D, and the repeats were homologous to those found in xylanase A from S. lividans, coagulation factor G subunit alpha from the horseshoe crab, Rarobacter faecitabidus protease I, beta-1,3-glucanase from Oerskovia xanthineolytica, and the ricin B chain. However, the repeats did not show sequence similarity to any of the nine known families of cellulose-binding domains (CBDs). On the other hand, STX-II and STX-III contained identical family II CBDs in their C-terminal regions.
Tsujibo
H
H
Osaka University of Pharmaceutical Sciences, Japan. tsujibo@oysun01.oups.ac.jp
Ohtsuki
T
T
Iio
T
T
Yamazaki
I
I
Miyamoto
K
K
Sugiyama
M
M
Inamori
Y
Y
D000115:Acetylesterase / Q000235:genetics*; D000595:Amino Acid Sequence; D002482:Cellulose / Q000378:metabolism; D003001:Cloning, Molecular; D005798:Genes, Bacterial; D007527:Isoenzymes / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013302:Streptomyces / Q000201:enzymology / Q000235:genetics*; D043325:Xylan Endo-1,3-beta-Xylosidase; D014990:Xylans / Q000378:metabolism; D014995:Xylosidases / Q000235:genetics* / Q000378:metabolism
D007527:Isoenzymes; D014990:Xylans; D002482:Cellulose; D000115:Acetylesterase; C081851:acetylxylan esterase; D014995:Xylosidases; D043325:Xylan Endo-1,3-beta-Xylosidase