INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2023
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IF 8.2
Xiaoxiao Li,Tong Jiang,Yu Wang,Jingjing Dong,Zhengyu Jin,Yuxiang Bai
Limosilactobacillus reuteri 121 4,6-α-glucanotransferase (GtfBΔN) modifies starch by cleaving (α1 → 4) linkages and introducing non-branched (α1 → 6) linkages to produce functional starch derivatives. Research has mainly focused on GtfBΔN converting amylose (linear substrate), whereas the conversion of amylopectin (branched substrate) has not been studied in detail. In this study, we used GtfBΔN to understand amylopectin modification and performed a set of experiments to analyze this modification pattern. The donor substrates were segments from the non-reducing ends to the nearest branch point in amylopectin as shown from the results of the chain length distribution of GtfBΔN-modified starches. Decreased and increased contents of β-limit dextrin and reducing sugars, respectively, during the incubation of β-limit dextrin with GtfBΔN indicated that the segments from the reducing end to the nearest branch point in amylopectin act as donor substrates. Dextranase was involved in the hydrolysis of the GtfBΔN conversion products of three different substrates groups, maltohexaose (G6), amylopectin, and G6 plus amylopectin. No reducing sugars were detected, therefore, amylopectin was not used as an acceptor substrate, and no non-branched (α1 → 6) linkages were introduced into it. Thus, these methods provide a reasonable and effective approach to studying GtfB-like 4,6-α-glucanotransferase in analyzing the roles and contribution of branched substrates.
研究领域:
生物化学
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微生物学
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食品科学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF VIROLOGY
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2023
·Vol. 97
·期 5
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IF 5.4
Renrong You,Kangchengyin Liu,Min Huang,Lihua Tang,Xuehui Zhang,Yahui Huang,Jing Zhao,Ye Zhao,Lilin Ye,Guozhong Zhang
Infectious bronchitis virus (IBV) infections are initiated by the transmembrane spike (S) glycoprotein, which binds to host factors and fuses the viral and cell membranes. The N-terminal domain of the S1 subunit of IBV S protein binds to sialic acids, but the precise location of the sialic acid binding domain (SABD) and the role of the SABD in IBV-infected chickens remain unclear. Here, we identify the S1 N-terminal amino acid (aa) residues 19 to 227 (209 aa total) of IBV strains SD (GI-19) and GD (GI-7), and the corresponding region of M41 (GI-1), as the minimal SABD using truncated protein histochemistry and neuraminidase assays. Both α-2,3- and α-2,6-linked sialic acids on the surfaces of CEK cells can be used as attachment receptors by IBV, leading to increased infection efficiency. However, 9-O acetylation of the sialic acid glycerol side chain inhibits IBV S1 and SABD protein binding. We further constructed recombinant strains in which the S1 gene or the SABD in the GD and SD genomes were replaced with the corresponding region from M41 by reverse genetics. Infecting chickens with these viruses revealed that the virulence and nephrotropism of rSDM41-S1, rSDM41-206, rGDM41-S1, and rGDM41-206 strains were decreased to various degrees compared to their parental strains. A positive sera cross-neutralization test showed that the serotypes were changed for the recombinant viruses. Our results provide insight into IBV infection of host cells that may aid vaccine design.IMPORTANCE To date, only α-2,3-linked sialic acid has been identified as a potential host binding receptor for IBV. Here, we show the minimum region constituting the sialic acid binding domain (SABD) and the binding characteristics of the S1 subunit of spike (S) protein of IBV strains SD (GI-19), GD (GI-7), and M41 (GI-1) to various sialic acids. The 9-O acetylation modification partially inhibits IBV from binding to sialic acid, while the virus can also bind to sialic acid molecules linked to host cells through an α-2,6 linkage, serving as another receptor determinant. Substitution of the putative SABD from strain M41 into strains SD and GD resulted in reduced virulence, nephrotropism, and a serotype switch. These findings suggest that sialic acid binding has diversified during the evolution of γ-coronaviruses, impacting the biological properties of IBV strains. Our results offer insight into the mechanisms by which IBV invades host cells.
研究领域:
病毒学
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分子生物学
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免疫学
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动物健康
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DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2024
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IF 7.7
Huimin Tian,Yachun Gu,Zili Lv,Liang Wang
Yoghurt fermented by Leuconostoc mesenteroides XR1 from Kefir grains was found to produce a unique silk drawing phenomenon. This property was found to be associated with the exopolysaccharides (EPS), X-EPS, produced by strain XR1. In order to better understand the mechanism that produced this phenomenon, the X-EPS was extracted, purified and characterized. The molecular weight and monosaccharide composition were determined by size exclusion chromatography coupled with multi-angle laser light scattering (SEC-MALLS) and ion chromatography (IC) analysis, respectively. The results showed that its molecular weight was 4.183 × 10 6 g/mol and its monosaccharide composition was glucose, and glucuronic acid , with the contents of 567.6148 and 0.2096 μg/mg, respectively. FT-IR and NMR analyses showed that X-EPS was an α-pyranose polysaccharide and was composed of 92.22 % α-(1 → 6) linked d -glucopyranose units and 7.77 % α-(1 → 3) branching. Furthermore, it showed a chain-like microstructure with branches in atomic force microscopy (AFM) and scanning electron microscopy (SEM) experiments. These results suggested that the unique structure of X-EPS, gave the yoghurt a strong viscosity and cohesiveness, which resulted in the silk drawing phenomenon. This work suggested that X-EPS holds the potential for food and industrial applications.
研究领域:
食品科学
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微生物学
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聚合物化学
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生物技术
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产品关联
DOI
PubMed
高影响因子
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