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Chen L, Wang Y, Liu J, Hong Z, Wong KH, Chiou JC, Xu B, Cespedes-Acuña CL, Bai W, Tian L. Structural characteristics and in vitro fermentation patterns of polysaccharides from Boletus mushrooms. Food Funct 2023; 14:7912-7923. [PMID: 37548291 DOI: 10.1039/d3fo01085f] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
The aim of this study was to investigate the structural characteristics and in vitro fermentation patterns of polysaccharides from Boletus mushrooms. Polysaccharides were solubilized from fruit bodies of selected mushrooms Boletus auripes, B. bicolor, and B. griseus using subcritical water extraction. Boletus polysaccharides were characterized for their general physicochemical pattern, constituent monosaccharides and molecular weight. A simulated in vitro fermentation model was used to study the utilization of Boletus polysaccharides by the gut microbiota and their consequent modulation of microbial communities. Results showed that the main constituent monosaccharides of Boletus polysaccharides were glucose, galactose and mannose, followed by fucose, xylose and rhamnose, with glucose being the most abundant. The polysaccharides from B. bicolor and B. griseus exhibited a relatively high proportion of galactose and mannose, respectively. Boletus polysaccharides exhibited a wide range of molecular weights (5 kDa to 2000 kDa), which covered multiple polysaccharide populations, but the proportions of these populations varied among the samples. Boletus polysaccharides were gradually utilized by the human fecal microbiota, promoting the production of SCFAs. Boletus polysaccharides contributed to a healthier gut microbiota composition by increasing the relative abundance of beneficial bacterial genera such as Bacteroides and Faecalibacterium and reducing the relative abundance of harmful bacterial genera such as Sutterella and Escherichia-Shigella. B. bicolor polysaccharides showed better fermentability and prebiotic effects than the other Boletus polysaccharide groups. Therefore, the consumption of select Boletus mushrooms, particularly B. bicolor, could be a potential approach to obtain polysaccharides for microbiota modulation and to support gut health.
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Affiliation(s)
- Li Chen
- Department of Food Science and Engineering, Institute of Food Safety and Nutrition, Guangdong Engineering Technology Center of Food Safety Molecular Rapid Detection, Jinan University, Guangzhou, 510632, China.
| | - Yuxin Wang
- Department of Food Science and Engineering, Institute of Food Safety and Nutrition, Guangdong Engineering Technology Center of Food Safety Molecular Rapid Detection, Jinan University, Guangzhou, 510632, China.
| | - Jiaxin Liu
- Department of Food Science and Engineering, Institute of Food Safety and Nutrition, Guangdong Engineering Technology Center of Food Safety Molecular Rapid Detection, Jinan University, Guangzhou, 510632, China.
| | - Zhiyuan Hong
- Department of Food Science and Engineering, Institute of Food Safety and Nutrition, Guangdong Engineering Technology Center of Food Safety Molecular Rapid Detection, Jinan University, Guangzhou, 510632, China.
| | - Ka-Hing Wong
- Research Institute for Future Food, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Jia-Chi Chiou
- Research Institute for Future Food, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Baojun Xu
- Food Science and Technology Program, BNU-HKBU United International College, Zhuhai, Guangdong 519087, China
| | - Carlos L Cespedes-Acuña
- Departamento de Ciencias Basicas, Facultad de Ciencias, Universidad del Bio Bio, Chillán, 3800708, Chile
| | - Weibin Bai
- Department of Food Science and Engineering, Institute of Food Safety and Nutrition, Guangdong Engineering Technology Center of Food Safety Molecular Rapid Detection, Jinan University, Guangzhou, 510632, China.
| | - Lingmin Tian
- Department of Food Science and Engineering, Institute of Food Safety and Nutrition, Guangdong Engineering Technology Center of Food Safety Molecular Rapid Detection, Jinan University, Guangzhou, 510632, China.
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Yu WX, Tang HH, Ye JJ, Xiao HH, Lam CY, Shum TF, Sun ZK, Li YZ, Zang XY, Du WC, Zhang JP, Kong TH, Zhou LP, Chiou JC, Kung CF, Mok KW, Hu J, Wong MS. Identification of the Microbial Transformation Products of Secoisolariciresinol Using an Untargeted Metabolomics Approach and Evaluation of the Osteogenic Activities of the Metabolites. Molecules 2023; 28:5742. [PMID: 37570714 PMCID: PMC10420892 DOI: 10.3390/molecules28155742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 07/24/2023] [Accepted: 07/26/2023] [Indexed: 08/13/2023] Open
Abstract
Secoisolariciresinol (SECO) is one of the major lignans occurring in various grains, seeds, fruits, and vegetables. The gut microbiota plays an important role in the biotransformation of dietary lignans into enterolignans, which might exhibit more potent bioactivities than the precursor lignans. This study aimed to identify, synthesize, and evaluate the microbial metabolites of SECO and to develop efficient lead compounds from the metabolites for the treatment of osteoporosis. SECO was fermented with human gut microbiota in anaerobic or micro-aerobic environments at different time points. Samples derived from microbial transformation were analyzed using an untargeted metabolomics approach for metabolite identification. Nine metabolites were identified and synthesized. Their effects on cell viability, osteoblastic differentiation, and gene expression were examined. The results showed that five of the microbial metabolites exerted potential osteogenic effects similar to those of SECO or better. The results suggested that the enterolignans might account for the osteoporotic effects of SECO in vivo. Thus, the presence of the gut microbiota could offer a good way to form diverse enterolignans with bone-protective effects. The current study improves our understanding of the microbial transformation products of SECO and provides new approaches for new candidate identification in the treatment of osteoporosis.
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Affiliation(s)
- Wen-Xuan Yu
- Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China; (W.-X.Y.); (H.-H.T.); (H.-H.X.); (C.-Y.L.); (T.-F.S.); (T.-H.K.); (J.-C.C.); (M.-S.W.)
| | - Hok-Him Tang
- Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China; (W.-X.Y.); (H.-H.T.); (H.-H.X.); (C.-Y.L.); (T.-F.S.); (T.-H.K.); (J.-C.C.); (M.-S.W.)
| | - Jun-Jie Ye
- Increasepharm (Tianjin) Innovative Medicine Institute Limited, Tianjin 300382, China; (J.-J.Y.); (Z.-K.S.); (Y.-Z.L.); (X.-Y.Z.); (W.-C.D.); (J.-P.Z.)
| | - Hui-Hui Xiao
- Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China; (W.-X.Y.); (H.-H.T.); (H.-H.X.); (C.-Y.L.); (T.-F.S.); (T.-H.K.); (J.-C.C.); (M.-S.W.)
- State Key Laboratory of Chinese Medicine and Molecular Pharmacology (Incubation), Shenzhen Research Institute of the Hong Kong Polytechnic University, Shenzhen 518057, China
- Research Centre for Chinese Medicine Innovation, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China;
| | - Chung-Yan Lam
- Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China; (W.-X.Y.); (H.-H.T.); (H.-H.X.); (C.-Y.L.); (T.-F.S.); (T.-H.K.); (J.-C.C.); (M.-S.W.)
| | - Tim-Fat Shum
- Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China; (W.-X.Y.); (H.-H.T.); (H.-H.X.); (C.-Y.L.); (T.-F.S.); (T.-H.K.); (J.-C.C.); (M.-S.W.)
| | - Zhi-Kang Sun
- Increasepharm (Tianjin) Innovative Medicine Institute Limited, Tianjin 300382, China; (J.-J.Y.); (Z.-K.S.); (Y.-Z.L.); (X.-Y.Z.); (W.-C.D.); (J.-P.Z.)
| | - Yuan-Zhen Li
- Increasepharm (Tianjin) Innovative Medicine Institute Limited, Tianjin 300382, China; (J.-J.Y.); (Z.-K.S.); (Y.-Z.L.); (X.-Y.Z.); (W.-C.D.); (J.-P.Z.)
| | - Xin-Yu Zang
- Increasepharm (Tianjin) Innovative Medicine Institute Limited, Tianjin 300382, China; (J.-J.Y.); (Z.-K.S.); (Y.-Z.L.); (X.-Y.Z.); (W.-C.D.); (J.-P.Z.)
| | - Wen-Chao Du
- Increasepharm (Tianjin) Innovative Medicine Institute Limited, Tianjin 300382, China; (J.-J.Y.); (Z.-K.S.); (Y.-Z.L.); (X.-Y.Z.); (W.-C.D.); (J.-P.Z.)
| | - Jian-Ping Zhang
- Increasepharm (Tianjin) Innovative Medicine Institute Limited, Tianjin 300382, China; (J.-J.Y.); (Z.-K.S.); (Y.-Z.L.); (X.-Y.Z.); (W.-C.D.); (J.-P.Z.)
| | - Tsz-Hung Kong
- Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China; (W.-X.Y.); (H.-H.T.); (H.-H.X.); (C.-Y.L.); (T.-F.S.); (T.-H.K.); (J.-C.C.); (M.-S.W.)
| | - Li-Ping Zhou
- Research Centre for Chinese Medicine Innovation, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China;
| | - Jia-Chi Chiou
- Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China; (W.-X.Y.); (H.-H.T.); (H.-H.X.); (C.-Y.L.); (T.-F.S.); (T.-H.K.); (J.-C.C.); (M.-S.W.)
- Research Institute for Future Food, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
| | - Chun-Fai Kung
- Increasepharm (HK) Limited, Hong Kong Science Park, Shatin, Hong Kong, China;
| | - Kam-Wah Mok
- Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China; (W.-X.Y.); (H.-H.T.); (H.-H.X.); (C.-Y.L.); (T.-F.S.); (T.-H.K.); (J.-C.C.); (M.-S.W.)
- State Key Laboratory of Chinese Medicine and Molecular Pharmacology (Incubation), Shenzhen Research Institute of the Hong Kong Polytechnic University, Shenzhen 518057, China
- Research Centre for Chinese Medicine Innovation, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China;
| | - Jing Hu
- Increasepharm (Tianjin) Innovative Medicine Institute Limited, Tianjin 300382, China; (J.-J.Y.); (Z.-K.S.); (Y.-Z.L.); (X.-Y.Z.); (W.-C.D.); (J.-P.Z.)
| | - Man-Sau Wong
- Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China; (W.-X.Y.); (H.-H.T.); (H.-H.X.); (C.-Y.L.); (T.-F.S.); (T.-H.K.); (J.-C.C.); (M.-S.W.)
- State Key Laboratory of Chinese Medicine and Molecular Pharmacology (Incubation), Shenzhen Research Institute of the Hong Kong Polytechnic University, Shenzhen 518057, China
- Research Centre for Chinese Medicine Innovation, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China;
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Ho YW, Lim JY, Yeoh YK, Chiou JC, Zhu Y, Lai KP, Li L, Chan PKS, Fang JKH. Preliminary Findings of the High Quantity of Microplastics in Faeces of Hong Kong Residents. Toxics 2022; 10:toxics10080414. [PMID: 35893847 PMCID: PMC9394468 DOI: 10.3390/toxics10080414] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 07/17/2022] [Accepted: 07/17/2022] [Indexed: 02/06/2023]
Abstract
Microplastics are recognised as a ubiquitous and hazardous pollutant worldwide. These small-sized particles have been detected in human faeces collected from a number of cities, providing evidence of human ingestion of microplastics and their presence in the gastrointestinal tract. Here, using Raman spectroscopy, we identified an average of 50 particles g−1 (20.4–138.9 particles g−1 wet weight) in faeces collected from a healthy cohort in Hong Kong. This quantity was about five times higher than the values reported in other places in Asia and Europe. Polystyrene was the most abundant polymer type found in the faeces, followed by polypropylene and polyethylene. These particles were primarily fragments, but about two-thirds of the detected polyethylene terephthalate were fibres. More than 88% of the microplastics were smaller than 300 µm in size. Our study provides the first data on the faecal level, and thus the extent of ingestion, of microplastics in Hong Kong’s population. This timely assessment is crucial and supports the recently estimated ingestion rate of microplastics by Hong Kong residents through seafood consumption, which is one of the highest worldwide. These findings may be applicable to other coastal populations in South China with similar eating habits.
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Affiliation(s)
- Yuen-Wa Ho
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Hong Kong 999077, China; (Y.-W.H.); (J.-C.C.); (Y.Z.)
| | - Jin Yan Lim
- Department of Microbiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Sha Tin, Hong Kong 999077, China; (J.Y.L.); (Y.K.Y.); (P.K.S.C.)
| | - Yun Kit Yeoh
- Department of Microbiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Sha Tin, Hong Kong 999077, China; (J.Y.L.); (Y.K.Y.); (P.K.S.C.)
- Centre for Gut Microbiota Research, The Chinese University of Hong Kong, Prince of Wales Hospital, Sha Tin, Hong Kong 999077, China
- Microbiota I-Centre, Sha Tin, Hong Kong 999077, China
| | - Jia-Chi Chiou
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Hong Kong 999077, China; (Y.-W.H.); (J.-C.C.); (Y.Z.)
- Research Institute for Future Food, The Hong Kong Polytechnic University, Hung Hom, Hong Kong 999077, China
| | - Yuyan Zhu
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Hong Kong 999077, China; (Y.-W.H.); (J.-C.C.); (Y.Z.)
- Research Institute for Future Food, The Hong Kong Polytechnic University, Hung Hom, Hong Kong 999077, China
| | - Keng Po Lai
- Guangxi Key Laboratory of Tumor Immunology and Microenvironmental Regulation, Guilin Medical University, Guilin 541004, China;
- Department of Chemistry, City University of Hong Kong, Kowloon Tong, Hong Kong 999077, China
| | - Lei Li
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China;
| | - Paul Kay Sheung Chan
- Department of Microbiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Sha Tin, Hong Kong 999077, China; (J.Y.L.); (Y.K.Y.); (P.K.S.C.)
- Centre for Gut Microbiota Research, The Chinese University of Hong Kong, Prince of Wales Hospital, Sha Tin, Hong Kong 999077, China
| | - James Kar-Hei Fang
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Hong Kong 999077, China; (Y.-W.H.); (J.-C.C.); (Y.Z.)
- Research Institute for Future Food, The Hong Kong Polytechnic University, Hung Hom, Hong Kong 999077, China
- State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon Tong, Hong Kong 999077, China
- Correspondence:
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Yan YJ, Tsai YC, Ko ML, Lee NC, Chiou JC, Ou-Yang M. Quantitative examination of early diabetes by light-emitting diodes light-induced pupillary light reflex. Rev Sci Instrum 2021; 92:014101. [PMID: 33514206 DOI: 10.1063/5.0030042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 12/17/2020] [Indexed: 06/12/2023]
Abstract
This study investigated the abnormal pupillary light reflex in patients with early diabetes mellitus (DM) without retinopathy by using a custom-made noninvasive portable pupilometer. The pupilometer recorded and analyzed the pupillary light reflex. Two light intensities, 0.2 cd and 1.2 cd, and four wavelengths of stimulus light-white (400 nm-800 nm), red (640 ± 5 nm), green (534 ± 5 nm), and blue (470 ± 5 nm)-were used to stimulate the pupil for 10 ms. The pupillary response was recorded for 15 s. A total of 40 healthy people and 40 people with DM without retinopathy participated in the experiment at the National Taiwan University Hospital. The mean and standard deviation of DM duration were 4.5 years and 3.9 years. Of the 16 indices, the duration that pupil restores from its minimum size to half of its resting size (DRP), maximum pupil restoration velocity (MRV), and average restoration velocity (ARV) exhibited the most significant differences between the healthy people and those with DM. Compared with healthy participants, DRP was 16.33% higher, and MRV and ARV were 17.45% and 4.58% lower, respectively, in those with DM. This might be attributable to the sympathetic nervous system (SNS) controlling the dilator muscle during the dark-adapted period and relaxing the pupil; the SNS had few degenerated nerve endings in people with DM. The three aforementioned indices might be used to evaluate the severity of autonomic neuropathy in early DM.
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Affiliation(s)
- Y J Yan
- Institute of Electrical and Control Engineering, National Chiao Tung University, Hsinchu City 300, Taiwan
| | - Y C Tsai
- Institute of Electrical and Control Engineering, National Chiao Tung University, Hsinchu City 300, Taiwan
| | - M L Ko
- National Taiwan University Hospital Hsinchu Branch, Hsinchu 300, Taiwan
| | - N C Lee
- National Taiwan University Hospital, Taipei 100, Taiwan
| | - J C Chiou
- Institute of Electrical and Control Engineering, National Chiao Tung University, Hsinchu City 300, Taiwan
| | - M Ou-Yang
- Institute of Electrical and Control Engineering, National Chiao Tung University, Hsinchu City 300, Taiwan
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Song AX, Li LQ, Yin JY, Chiou JC, Wu JY. Mechanistic insights into the structure-dependant and strain-specific utilization of wheat arabinoxylan by Bifidobacterium longum. Carbohydr Polym 2020; 249:116886. [PMID: 32933699 DOI: 10.1016/j.carbpol.2020.116886] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 08/01/2020] [Accepted: 08/01/2020] [Indexed: 12/11/2022]
Abstract
Arabinoxylan (AX), an important dietary fiber from cereal grains, is mainly metabolised in the large intestine by gut bacteria, especially bifidobacteria. This study investigated the uptake and metabolism of wheat AX by a Bifidobacterium longum strain that could grow well with AX as the sole carbon source. The bacterial growth rate showed a significant correlation to the molecular weight (MW) of AX and its acid hydrolysates. Assessment of the key AX degrading enzymes suggested that the uptake and consumption of AX involved extracellular cleavage of xylan backbone and intracellular degradation of both the backbone and the arabinose substitution. The preference for native or partially hydrolysed AX with single substitutions and a sufficiently high MW suggested the structure-dependant uptake by the bacterial cells. Genetic analysis of B. longum showed the lack of β-xylosidase, suggesting the existence of unknown enzymes or dual/multiple-specific enzymes for hydrolysis of the non-reducing end of xylan backbone.
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Affiliation(s)
- Ang-Xin Song
- Food Safety and Technology Research Center, Department of Applied Biology & Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Long-Qing Li
- Food Safety and Technology Research Center, Department of Applied Biology & Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Jun-Yi Yin
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi, 330047, China
| | - Jia-Chi Chiou
- Food Safety and Technology Research Center, Department of Applied Biology & Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
| | - Jian-Yong Wu
- Food Safety and Technology Research Center, Department of Applied Biology & Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
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Cheng HW, Jeng BM, Chen CY, Huang HY, Chiou JC, Luo CH. The rectenna design on contact lens for wireless powering of the active intraocular pressure monitoring system. Annu Int Conf IEEE Eng Med Biol Soc 2015; 2013:3447-50. [PMID: 24110470 DOI: 10.1109/embc.2013.6610283] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This paper proposed a wireless power harvesting system with micro-electro-mechanical-systems (MEMS) fabrication for noninvasive intraocular pressure (IOP) measurement on soft contact lens substructure. The power harvesting IC consists of a loop antenna, an impedance matching network and a rectifier. The proposed IC has been designed and fabricated by CMOS 0.18 um process that operates at the ISM band of 5.8 GHz. The antenna and the power harvesting IC would be bonded together by using flip chip bonding technologies without extra wire interference. The circuit utilized an impedance transformation circuit to boost the input RF signal that improves the circuit performance. The proposed design achieves an RF-to-DC conversion efficiency of 35% at 5.8 GHz.
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Chiou JC, Li XP, Remacha M, Ballesta JPG, Tumer NE. Shiga toxin 1 is more dependent on the P proteins of the ribosomal stalk for depurination activity than Shiga toxin 2. Int J Biochem Cell Biol 2011; 43:1792-801. [PMID: 21907821 DOI: 10.1016/j.biocel.2011.08.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Revised: 07/27/2011] [Accepted: 08/26/2011] [Indexed: 01/01/2023]
Abstract
Shiga toxins produced by Escherichia coli O157:H7 are responsible for food poisoning and hemolytic uremic syndrome (HUS). The A subunits of Shiga toxins (Stx1A and Stx2A) inhibit translation by depurinating a specific adenine in the large rRNA. To determine if Stx1A and Stx2A require the ribosomal stalk for depurination, their activity and cytotoxicity were examined in the yeast P protein deletion mutants. Stx1A and Stx2A were less toxic and depurinated ribosomes less in a strain lacking P1/P2 on the ribosome and in the cytosol (ΔP2) than in a strain lacking P1/P2 on the ribosome, but containing free P2 in the cytosol (ΔP1). To determine if cytoplasmic P proteins facilitated depurination, Stx1A and Stx2A were expressed in the P0ΔAB mutant, in which the binding sites for P1/P2 were deleted on the ribosome, and P1/P2 accumulated in the cytosol. Stx1A was less toxic and depurinated ribosomes less in P0ΔAB, suggesting that intact binding sites for P1/P2 were critical. In contrast, Stx2A was toxic and depurinated ribosomes in P0ΔAB as in wild type, suggesting that it did not require the P1/P2 binding sites. Depurination of ΔP1, but not P0ΔAB ribosomes increased upon addition of purified P1α/P2βin vitro, and the increase was greater for Stx1 than for Stx2. We conclude that cytoplasmic P proteins stimulate depurination by Stx1 by facilitating the access of the toxin to the ribosome. Although ribosomal stalk is important for Stx1 and Stx2 to depurinate the ribosome, Stx2 is less dependent on the stalk proteins for activity than Stx1 and can depurinate ribosomes with an incomplete stalk better than Stx1.
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Affiliation(s)
- Jia-Chi Chiou
- Department of Plant Biology and Pathology, School of Environmental and Biological Sciences, Rutgers University, 59 Dudley Road, New Brunswick, NJ 08901-8520, USA
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Li XP, Chiou JC, Remacha M, Ballesta JPG, Tumer NE. A two-step binding model proposed for the electrostatic interactions of ricin a chain with ribosomes. Biochemistry 2009; 48:3853-63. [PMID: 19292477 DOI: 10.1021/bi802371h] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Ricin is a ribosome inactivating protein that catalytically removes a universally conserved adenine from the alpha-sarcin/ricin loop (SRL) of the 28S rRNA. We recently showed that ricin A chain (RTA) interacts with the P1 and P2 proteins of the ribosomal stalk to depurinate the SRL in yeast. Here we examined the interaction of RTA with wild-type and mutant yeast ribosomes deleted in the stalk proteins by surface plasmon resonance. The interaction between RTA and wild-type ribosomes did not follow a single-step binding model but was best characterized by two distinct types of interactions. The AB1 interaction had very fast association and dissociation rates, was saturable, and required an intact stalk, while the AB2 interaction had slower association and dissociation rates, was not saturable, and did not require the stalk. RTA interacted with the mutant ribosomes by a single type of interaction, which was similar to the AB2 interaction with the wild-type ribosomes. Both interactions were dominated by electrostatic interactions, and the AB1 interaction was stronger than the AB2 interaction. On the basis of these results, we propose a two-step interaction model. The slow and ribosomal stalk nonspecific AB2 interactions concentrate the RTA molecules on the surface of the ribosome. The AB2 interactions facilitate the diffusion of RTA toward the stalk and promote the faster, more specific AB1 interactions with the ribosomal stalk. The electrostatic AB1 and AB2 interactions work together allowing RTA to depurinate the SRL at a much higher rate on the intact ribosomes than on the naked 28S rRNA.
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Affiliation(s)
- Xiao-Ping Li
- Biotechnology Center for the Agriculture and the Environment, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, New Jersey 08901-8520, USA
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Chiou JC, Li XP, Remacha M, Ballesta JPG, Tumer NE. The ribosomal stalk is required for ribosome binding, depurination of the rRNA and cytotoxicity of ricin A chain in Saccharomyces cerevisiae. Mol Microbiol 2008; 70:1441-52. [PMID: 19019145 DOI: 10.1111/j.1365-2958.2008.06492.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ribosome inactivating proteins (RIPs) like ricin, pokeweed antiviral protein (PAP) and Shiga-like toxins 1 and 2 (Stx1 and Stx2) share the same substrate, the alpha-sarcin/ricin loop, but differ in their specificities towards prokaryotic and eukaryotic ribosomes. Ricin depurinates the eukaryotic ribosomes more efficiently than the prokaryotic ribosomes, while PAP can depurinate both types of ribosomes. Accumulating evidence suggests that different docking sites on the ribosome might be used by different RIPs, providing a basis for understanding the mechanism underlying their kingdom specificity. Our previous results demonstrated that PAP binds to the ribosomal protein L3 to depurinate the alpha-sarcin/ricin loop and binding of PAP to L3 was critical for its cytotoxicity. Here, we used surface plasmon resonance to demonstrate that ricin toxin A chain (RTA) binds to the P1 and P2 proteins of the ribosomal stalk in Saccharomyces cerevisiae. Ribosomes from the P protein mutants were depurinated less than the wild-type ribosomes when treated with RTA in vitro. Ribosome depurination was reduced when RTA was expressed in the DeltaP1 and DeltaP2 mutants in vivo and these mutants were more resistant to the cytotoxicity of RTA than the wild-type cells. We further show that while RTA, Stx1 and Stx2 have similar requirements for ribosome depurination, PAP has different requirements, providing evidence that the interaction of RIPs with different ribosomal proteins is responsible for their ribosome specificity.
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Affiliation(s)
- Jia-Chi Chiou
- Biotechnology Center for the Agriculture and the Environment, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ 08901-8520 USA
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