Characterization of a PA14 domain-containing galactofuranose-specific β-D-galactofuranosidase from Streptomyces sp.
Characterization of a PA14 domain-containing galactofuranose-specific β-D-galactofuranosidase from Streptomyces sp.
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链霉菌中含有 PA14 结构域的呋喃半乳糖特异性 β-D-呋喃半乳糖苷酶的表征。
DOI：
10.1080/09168451.2017.1300518
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Takegawa K.
中科院分区：
文献类型：
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作者：
Matsunaga E.;Higuchi Y.;Mori K.;Yairo N.;Toyota S.;Oka T.;Tashiro K.;Takegawa K.
呋喃半乳糖(β-d-GalactoFuranose，GALF)作为多糖和糖偶联物的组成部分，存在于多种病原微生物体内。虽然我们最近在链霉菌JHA19中发现了β-d-呋喃半乳糖苷酶基因ORF1110，但对该基因的研究还很少。在此，我们鉴定了一株菌株，命名为JHA26，其培养上清液对4-硝基苯基β-d-呋喃半乳糖苷(PnP-β-d-GALF)具有半乳糖酶活性。JHA26菌株的基因组测序草案显示了一个被称为ORF0643的假定基因，它编码含有PA14结构域的GalF-ase，被认为具有底物识别功能。在大肠杆菌中表达的重组蛋白具有半乳糖半乳糖苷酶活性，同时也释放了烟曲霉半乳甘露聚糖的半乳糖残基，表明该酶是一种外型半乳糖酶。用ORF0643和ORF1110 Galf酶的氨基酸序列进行BLAST搜索发现放线杆菌中有两种Galf酶，这表明Galf特异性Galf酶可能表现出不同的底物特异性。
As a constituent of polysaccharides and glycoconjugates, β-d-galactofuranose (Galf) exists in several pathogenic microorganisms. Although we recently identified a β-d-galactofuranosidase (Galf-ase) gene, ORF1110, in theStreptomycesstrain JHA19, very little is known about the Galf-ase gene. Here, we characterized a strain, named JHA26, in the culture supernatant of which exhibited Galf-ase activity for 4-nitrophenyl β-d-galactofuranoside (pNP-β-d-Galf) as a substrate. Draft genome sequencing of the JHA26 strain revealed a putative gene, termed ORF0643, that encodes Galf-ase containing a PA14 domain, which is thought to function in substrate recognition. The recombinant protein expressed inEscherichia colishowed the Galf-specific Galf-ase activity and also released galactose residue of the polysaccharide galactomannan prepared fromAspergillus fumigatus, suggesting that this enzyme is an exo-type Galf-ase. BLAST searches using the amino acid sequences of ORF0643 and ORF1110 Galf-ases revealed two types of Galf-ases in Actinobacteria, suggesting that Galf-specific Galf-ases may exhibit discrete substrate specificities.