JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
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2024
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IF 5.7
Chengqiang Li,Zhuoning Cao,Hong Jiang,Francesco Secundo,Xiangzhao Mao
β-N-Acetylhexosaminidases have attracted much attention in the enzymatic synthesis of lacto-N-triose II (LNT2) as a backbone precursor of human milk oligosaccharides (HMOs). In this study, a novel glycoside hydrolase (GH) 20 family β-N-acetylhexosaminidase, FlaNag2353, from Flavobacterium algicola was biochemically characterized and applied to synthesize LNT2. FlaNag2353 displayed optimal activity to p-nitrophenyl N-acetyl-β-d-glucosaminide (pNP-GlcNAc) at 40 °C and pH 8.0. In addition to its excellent hydrolysis activity toward pNP-GlcNAc and chitooligosaccharides, FlaNag2353 showed trans-glycosylation activity. Under conditions of pH 9.0 and 55 °C for 2 h and utilizing 200 mM lactose and 10 mM pNP-GlcNAc, FlaNag2353 synthesized LNT2 with a conversion ratio of 4.15% calculated from pNP-GlcNAc. Moreover, when applied to LNT2 synthesis with 10 mM pNP-GlcNAc and 9.7% (w/v) industrial waste whey powder, FlaNag2353 achieved a conversion ratio of 2.39%. This study has significant implications for broadening the applications of GH20 β-N-acetylhexosaminidases and promoting the high-value utilization of whey powder.
研究领域:
生物化学
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酶学
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食品科学
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生物技术
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DOI
PubMed
高影响因子
ISME Journal
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2021
·Vol. 15
·期 6
·1844-1857
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IF 10.302
Liu Qing,Li Wei,Liu Di,Li Lingyan,Li Jie,Lv Na,Liu Fei,Zhu Baoli,Zhou Yuguang,Xin Yuhua,Dong Xiuzhu
Bacteria that inhabit glaciers usually produce carotenoids. Here, we report that a group of zeaxanthin-producing glacial Flavobacterium exhibited light-promoted growth. Of the tested 47 strains, 45 showed increased growths but two died under illumination at 50 μmol photon m −2 s −1 . Light stimulation occurred mainly in either anoxic or nutrient-poor cultures, while the same levels of light promotion were found for that grown at 14 and 7 °C. Pigment assays identified overrepresentative zeaxanthin but trace retinal in the light promoted 45 strains, while flexirubin was exclusively in the light-lethal two. Genomic analysis revealed the gene cluster for zeaxanthin synthesis in the 45 strains, in which 37 strains also harbored the proteorhodopsin gene prd . Transcriptomic analysis found that light-induced expressions of both the zeaxanthin synthesis and proteorhodopsin genes. Whereas, deletion of the prd gene in one strain did not diminish light promotion, inhibition of zeaxanthin synthesis did. In comparison, no light promotion was determined in a glacier Cryobacterium luteum that produced a non-zeaxanthin-type carotenoid. Therefore, light stimulation on the glacial Flavobacterium is mostly likely related to zeaxanthin, which could provide better photoprotection and sustain membrane integrity for the organisms living in cold environments.
研究领域:
微生物学
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环境科学
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分子生物学
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DOI
PubMed
高影响因子
Marine Drugs
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2022
·Vol. 20
·期 8
·533
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IF 6.085
Juanjuan Wang,Zebin Liu,Xiaowei Pan,Ning Wang,Legong Li,Yuguang Du,Jianjun Li,Mei Li
Fucoidans represent a type of polyanionic fucose-containing sulfated polysaccharides (FCSPs) that are cleaved by fucoidan-degrading enzymes, producing low-molecular-weight fucoidans with multiple biological activities suitable for pharmacological use. Most of the reported fucoidan-degrading enzymes are glycoside hydrolases, which have been well studied for their structures and catalytic mechanisms. Little is known, however, about the rarer fucoidan lyases, primarily due to the lack of structural information. FdlA fromFlavobacteriumsp. SA-0082 is an endo-type fucoidan-degrading enzyme that cleaves the sulfated fuco-glucuronomannan (SFGM) through a lytic mechanism. Here, we report nine crystal structures of the catalytic N-terminal domain of FdlA (FdlA-NTD), in both its wild type (WT) and mutant forms, at resolutions ranging from 1.30 to 2.25 Å. We show that the FdlA-NTD adopts a right-handed parallel β-helix fold, and possesses a substrate binding site composed of a long groove and a unique alkaline pocket. Our structural, biochemical, and enzymological analyses strongly suggest that FdlA-NTD utilizes catalytic residues different from other β-helix polysaccharide lyases, potentially representing a novel polysaccharide lyase family.Keywords:fucoidan lyase;polysaccharides;crystal structure;catalytic mechanism
研究领域:
生物化学
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结构生物学
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DOI
PubMed
高影响因子
Frontiers in Veterinary Science
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2026
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IF 3.1
Ruoxi Zhu,Liang Zhong,Yuying Xun,Shucheng Zheng,Yongtao Zhu,Wenlong Cai
Columnaris disease, caused by Flavobacterium columnare, represents one of the most economically devastating bacterial infections in global freshwater aquaculture. Despite its significant impact, the molecular mechanisms underlying F. columnare pathogenesis remain largely unexplored. Signal peptide peptidase A (SppA) plays a crucial role in bacterial protein secretion by degrading residual signal peptides after protein translocation, yet its function in F. columnare physiology and virulence has not been characterized. Here, we employed a targeted in-frame gene knockout approach to investigate the role of sppA in F. columnare. The ΔsppA mutant exhibited pleiotropic phenotypes including increased outer membrane vesicle (OMV) production (3.8-fold higher compared to the wild type), loss of gliding motility, enhanced efflux pump activity at the transcriptomic level, and reduced virulence. Transcriptomic profiling of the ΔsppA mutant revealed significant upregulation of genes involved in membrane stress response, including the genes in the MacAB-TolC efflux system, algU, and osmC, compared to the wild-type state. Importantly, survival assays demonstrated its virulence was significantly attenuated in freshwater Medaka (Oryzias latipes), with a 20% higher survival rate of fish compared to the wild type. Our findings reveal that SppA is essential for maintaining membrane homeostasis and normal cellular physiology in F. columnare and serves as one of the virulence factors during columnaris infection. These results provide important insights into the biological function of the sppA gene in F. columnare and highlight its role in bacterial protein secretion, membrane homeostasis, and pathogenesis.
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DOI
高影响因子
BIOCHEMICAL ENGINEERING JOURNAL
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2022
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IF 4.446
Jiaheng Wang,Nuo Zhang,Yawen Huang,Shunyi Li,Guimin Zhang
p -Coumaric acid (para-hydroxycinnamic acid, p -HCA), as a kind of natural active substance from plant cell walls, is widely used in medicine, food, and cosmetics with its antioxidant, anticancer, and other properties. Biological production of p -HCA can be achieved via one-step deamination of the L -tyrosine by tyrosine ammonia-lyase (TAL). Here, a new highly active TAL ( Fc -TAL) from Flavobacterium columnare was identified via gene mining and heterologous expression . The purified Fc -TAL completely converts 22 mM L -tyrosine to p -HCA under alkaline condition (pH 9.5–10.0) at 55 °C. To increase enzymatic recyclability and reduce the bioproduction cost, Fc -TAL was immobilized on a silica nanospheres through silica-binding peptides (SiBP2) at pH 10. In comparison to free enzyme , the immobilized TAL SiBP2 exhibited higher stability, over 50% activity was retained even after 10 consecutive catalytic cycles. Further experiments revealed that an aliquot of immobilized enzyme (about 200 mg TAL) can transform 20 g L -tyrosine into17.8 g p -HCA with 96% yields and 98% purity through 5 consecutive reaction cycles. Our studies not only provided a strategy for enzyme immobilization in alkaline condition, but also developed a green process for p -coumaric acid biosynthesis with the highest conversion rate and yield reported to date.
研究领域:
生物化学
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生物技术
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酶学
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药学
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DOI
高影响因子
ACS Omega
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2020
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IF 2.87
Xueyu Liu,Hongguang Zhu
The traditional biological denitrification process has the problems of low removal rates and lack of a carbon source when treating wastewater with high ammonia nitrogen concentration and a low carbon–nitrogen ratio. Based on a bio-electrochemical system (BES), a novel carbon cloth bipolar plate multicompartment electroenhanced bioreactor (CBM-EEB) system was constructed. In this study, nitrogen removal efficiency and enrichment of functional bacteria using CBM-EEB under different voltage conditions were investigated. The results from next-generation sequencing indicated that the CBM-EEB included heterotrophic nitrification and aerobic denitrification (HNAD) and was dominated by heterotrophic nitrification aerobic denitrifying bacteria (HNADB). The applied voltage was confirmed as having the ability to regulate the microbial community structure and abundance of functional genes, thereby further enhancing the nitrogen removal efficiency of the system. The total nitrogen removal efficiency was 77.70 ± 1.14, 87.10 ± 0.56, 86.40 ± 0.59, and 89.30 ± 0.53% under applied voltages of 0.4, 0.7, 1.0, and 1.3 V, respectively. All values were significantly higher than the control group (62.86 ± 2.06%). HNADB had the highest abundance among the 17 detected genera related to nitrogen metabolism. Facultative denitrifying bacteria, Pseudoxanthomonas, along with key bacteria of HNADB, such as Flavobacterium, constructed a shortcut simultaneous nitrification–denitrification (SND) process. Poisson analysis and redundancy analysis (RDA) showed that the applied voltage improved the denitrification efficiency by changing the microbial community structure, reducing the abundance of heterotrophic bacteria, and increasing the unit abundance of key functional genes so that less organics were required for the denitrification process. The increased nitrogen removal efficiency in the experimental group was mainly related to simultaneous nitrification–denitrification process and cooperation of microbial communities in the anode and the cathode. This study highlighted the feasibility of CBM-EEB to enhance the HNAD reaction and the response of wastewater with a low C/N ratio to enhance the abundance of microbial bacteria and their functional gene abundance.
研究领域:
环境工程
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生物技术
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微生物学
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废水处理
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DOI
PubMed
高影响因子
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