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Identification and characterization of β-d-galactofuranosidases from Aspergillus nidulans and Aspergillus fumigatus
Journal of Bioscience and Bioengineering ( IF 2.3 ) Pub Date : 2020-10-01 , DOI: 10.1016/j.jbiosc.2020.09.006
Emiko Matsunaga , Yutaka Tanaka , Saki Toyota , Hisae Yamada , Takuji Oka , Yujiro Higuchi , Kaoru Takegawa

Although β-d-galactofuranosidases (Galf-ases) that hydrolyze β-d-galactofuranose (Galf)-containing oligosaccharides have been characterized in various organisms, to date no Galf-specific Galf-ase-encoding genes have been reported in Aspergillus fungi. Based on the amino acid sequences of previously identified bacterial Galf-ases, here we found two candidate Galf-specific Galf-ase genes AN2395 (gfgA) and AN3200 (gfgB) in the genome of Aspergillus nidulans. Indeed, recombinant GfgA and GfgB proteins exhibited Galf-specific Galf-ase activity, but no detectable α-l-arabinofuranosidase (Araf-ase) activity. Phylogenetic analysis of GfgA and GfgB orthologs indicated that there are two types of Aspergillus species: those containing one ortholog each for GfgA and GfgB; and those containing only one ortholog in total, among which Aspergillus fumigatus there is a representative with a single ortholog Galf-ase Afu2g14520. Unlike GfgA and GfgB, the recombinant Afu2g14520 protein showed higher Araf-ase activity than Galf-ase activity. An assay of substrate specificity revealed that although GfgA and GfgB are both exo-type Galf-ases and hydrolyze β-(1,5) and β-(1,6) linkages, GfgA hydrolyzes β-(1,6)-linked Galf-oligosaccharide more effectively as compared with GfgB. Collectively, our findings indicate that Galf-ases in Aspergillus species may have a role in cooperatively degrading Galf-containing oligosaccharides depending on environmental conditions.



中文翻译:

构巢曲霉烟曲霉中β-d-半乳糖呋喃糖苷酶的鉴定与表征

虽然β- d -galactofuranosidases(加˚F -ases)水解β- d -galactofuranose(加˚F)含寡糖已经表征在多种生物没有加日期˚F特异性半乳糖˚F -ase编码基因已经报道在霉菌中。根据先前鉴定的细菌Gal f -ase的氨基酸序列,我们在构巢曲霉的基因组中发现了两个候选的Gal f-特异性Gal f -ase基因AN2395(gfgA)和AN3200(gfgB。实际上,重组GfgA和GfgB蛋白表现出Gal f-特异性Gal f-酶活性,但是没有可检测的α- 1- α-呋喃糖苷酶(Ara f -ase)活性。对GfgA和GfgB直系同源物的系统进化分析表明,曲霉属菌种有两种类型:GfgA和GfgB分别含有一个直系同源物的曲霉。以及仅包含一个直向同源物的那些,其中烟曲霉中有一个代表,带有一个直向同源物Gal f -ase Afu2g14520。与GfgA和GfgB不同,重组Afu2g14520蛋白显示的Ara f-酶活性高于Gal f酶活性。底物特异性的测定表明,尽管GfgA和GfgB都是外切型Gal f-酶并水解β-(1,5)和β-(1,6)键,但GfgA水解了β-(1,6)-键与GfgB相比,Gal f-寡糖更有效。总的来说,我们的发现表明,取决于环境条件,曲霉属物种中的Gal f-酶可能在协同降解含Gal f的寡糖中起作用。

更新日期:2020-10-01
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