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Tang X, Ravikumar Y, Zhang G, Yun J, Zhao M, Qi X. D-allose, a typical rare sugar: properties, applications, and biosynthetic advances and challenges. Crit Rev Food Sci Nutr 2024:1-28. [PMID: 38764407 DOI: 10.1080/10408398.2024.2350617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2024]
Abstract
D-allose, a C-3 epimer of D-glucose and an aldose-ketose isomer of D-allulose, exhibits 80% of sucrose's sweetness while being remarkably low in calories and nontoxic, making it an appealing sucrose substitute. Its diverse physiological functions, particularly potent anticancer and antitumor effects, render it a promising candidate for clinical treatment, garnering sustained attention. However, its limited availability in natural sources and the challenges associated with chemical synthesis necessitate exploring biosynthetic strategies to enhance production. This overview encapsulates recent advancements in D-allose's physicochemical properties, physiological functions, applications, and biosynthesis. It also briefly discusses the crucial role of understanding aldoketose isomerase structure and optimizing its performance in D-allose synthesis. Furthermore, it delves into the challenges and future perspectives in D-allose bioproduction. Early efforts focused on identifying and characterizing enzymes responsible for D-allose production, followed by detailed crystal structure analysis to improve performance through molecular modification. Strategies such as enzyme immobilization and implementing multi-enzyme cascade reactions, utilizing more cost-effective feedstocks, were explored. Despite progress, challenges remain, including the lack of efficient high-throughput screening methods for enzyme modification, the need for food-grade expression systems, the establishment of ordered substrate channels in multi-enzyme cascade reactions, and the development of downstream separation and purification processes.
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Affiliation(s)
- Xinrui Tang
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, China
| | - Yuvaraj Ravikumar
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, China
| | - Guoyan Zhang
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, China
| | - Junhua Yun
- School of Life Sciences, Guangzhou University, Guangzhou, China
| | - Mei Zhao
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, China
| | - Xianghui Qi
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, China
- School of Life Sciences, Guangzhou University, Guangzhou, China
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Yoshida H, Yamamoto N, Kurahara LH, Izumori K, Yoshihara A. X-ray structure and characterization of a probiotic Lactobacillus rhamnosus Probio-M9 L-rhamnose isomerase. Appl Microbiol Biotechnol 2024; 108:249. [PMID: 38430263 PMCID: PMC10908623 DOI: 10.1007/s00253-024-13075-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 01/18/2024] [Accepted: 02/16/2024] [Indexed: 03/03/2024]
Abstract
A recombinant L-rhamnose isomerase (L-RhI) from probiotic Lactobacillus rhamnosus Probio-M9 (L. rhamnosus Probio-M9) was expressed. L. rhamnosus Probio-M9 was isolated from human colostrum and identified as a probiotic lactic acid bacterium, which can grow using L-rhamnose. L-RhI is one of the enzymes involved in L-rhamnose metabolism and catalyzes the reversible isomerization between L-rhamnose and L-rhamnulose. Some L-RhIs were reported to catalyze isomerization not only between L-rhamnose and L-rhamnulose but also between D-allulose and D-allose, which are known as rare sugars. Those L-RhIs are attractive enzymes for rare sugar production and have the potential to be further improved by enzyme engineering; however, the known crystal structures of L-RhIs recognizing rare sugars are limited. In addition, the optimum pH levels of most reported L-RhIs are basic rather than neutral, and such a basic condition causes non-enzymatic aldose-ketose isomerization, resulting in unexpected by-products. Herein, we report the crystal structures of L. rhamnosus Probio-M9 L-RhI (LrL-RhI) in complexes with L-rhamnose, D-allulose, and D-allose, which show enzyme activity toward L-rhamnose, D-allulose, and D-allose in acidic conditions, though the activity toward D-allose was low. In the complex with L-rhamnose, L-rhamnopyranose was found in the catalytic site, showing favorable recognition for catalysis. In the complex with D-allulose, D-allulofuranose and ring-opened D-allulose were observed in the catalytic site. However, bound D-allose in the pyranose form was found in the catalytic site of the complex with D-allose, which was unfavorable for recognition, like an inhibition mode. The structure of the complex may explain the low activity toward D-allose. KEY POINTS: • Crystal structures of LrL-RhI in complexes with substrates were determined. • LrL-RhI exhibits enzyme activity toward L-rhamnose, D-allulose, and D-allose. • The LrL-RhI is active in acidic conditions.
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Affiliation(s)
- Hiromi Yoshida
- Department of Basic Life Science, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-Cho, Kita-Gun, Kagawa, 761-0793, Japan.
- International Institute of Rare Sugar Research and Education, Kagawa University, Takamatsu, Kagawa, Japan.
| | - Naho Yamamoto
- Faculty of Agriculture, Kagawa University, 2393 Ikenobe, Miki, Kagawa, 761-0795, Japan
| | - Lin Hai Kurahara
- Department of Cardiovascular Physiology, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-Cho, Kita-Gun, Kagawa, 761-0793, Japan
| | - Ken Izumori
- International Institute of Rare Sugar Research and Education, Kagawa University, Takamatsu, Kagawa, Japan
- Faculty of Agriculture, Kagawa University, 2393 Ikenobe, Miki, Kagawa, 761-0795, Japan
| | - Akihide Yoshihara
- International Institute of Rare Sugar Research and Education, Kagawa University, Takamatsu, Kagawa, Japan
- Faculty of Agriculture, Kagawa University, 2393 Ikenobe, Miki, Kagawa, 761-0795, Japan
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Chen Z, Chen J, Zhang W, Zhang T, Guang C, Mu W. Improving Thermostability and Catalytic Behavior of l-Rhamnose Isomerase from Caldicellulosiruptor obsidiansis OB47 toward d-Allulose by Site-Directed Mutagenesis. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:12017-12024. [PMID: 30370768 DOI: 10.1021/acs.jafc.8b05107] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
d-Allose, a rare sugar, is an ideal table-sugar substitute and has many advantageous physiological functions. l-Rhamnose isomerase (l-RI) is an important d-allose-producing enzyme, but it exhibits comparatively low catalytic activity on d-allulose. In this study, an array of hydrophobic residues located within β1-α1-loop were solely or collectively replaced with polar amino acids by site-directed mutagenesis. A group of mutants was designed to weaken the hydrophobic environment and strengthen the catalytic behavior on d-allulose. Compared with that of the wild-type enzyme, the relative activities of the V48N/G59N/I63N and V48N/G59N/I63N/F335S mutants toward d-allulose were increased by 105.6 and 134.1%, respectively. Another group of mutants was designed to enhance thermostability. Finally, the t1/2 values of mutant S81A were increased by 7.7 and 1.1 h at 70 and 80 °C, respectively. These results revealed that site-directed mutagenesis is efficient for improving thermostability and catalytic behavior toward d-allulose.
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Affiliation(s)
- Ziwei Chen
- State Key Laboratory of Food Science and Technology , Jiangnan University , Wuxi , Jiangsu 214122 , China
| | - Jiajun Chen
- State Key Laboratory of Food Science and Technology , Jiangnan University , Wuxi , Jiangsu 214122 , China
| | - Wenli Zhang
- State Key Laboratory of Food Science and Technology , Jiangnan University , Wuxi , Jiangsu 214122 , China
| | - Tao Zhang
- State Key Laboratory of Food Science and Technology , Jiangnan University , Wuxi , Jiangsu 214122 , China
| | - Cuie Guang
- State Key Laboratory of Food Science and Technology , Jiangnan University , Wuxi , Jiangsu 214122 , China
| | - Wanmeng Mu
- State Key Laboratory of Food Science and Technology , Jiangnan University , Wuxi , Jiangsu 214122 , China
- International Joint Laboratory on Food Safety , Jiangnan University , Wuxi , Jiangsu 214122 , China
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Regulation of the rhaEWRBMA Operon Involved in l-Rhamnose Catabolism through Two Transcriptional Factors, RhaR and CcpA, in Bacillus subtilis. J Bacteriol 2015; 198:830-45. [PMID: 26712933 DOI: 10.1128/jb.00856-15] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 12/15/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The Bacillus subtilis rhaEWRBMA (formerly yuxG-yulBCDE) operon consists of four genes encoding enzymes for l-rhamnose catabolism and the rhaR gene encoding a DeoR-type transcriptional regulator. DNase I footprinting analysis showed that the RhaR protein specifically binds to the regulatory region upstream of the rhaEW gene, in which two imperfect direct repeats are included. Gel retardation analysis revealed that the direct repeat farther upstream is essential for the high-affinity binding of RhaR and that the DNA binding of RhaR was effectively inhibited by L-rhamnulose-1-phosphate, an intermediate of L-rhamnose catabolism. Moreover, it was demonstrated that the CcpA/P-Ser-HPr complex, primarily governing the carbon catabolite control in B. subtilis, binds to the catabolite-responsive element, which overlaps the RhaR binding site. In vivo analysis of the rhaEW promoter-lacZ fusion in the background of ccpA deletion showed that the L-rhamnose-responsive induction of the rhaEW promoter was negated by the disruption of rhaA or rhaB but not rhaEW or rhaM, whereas rhaR disruption resulted in constitutive rhaEW promoter activity. These in vitro and in vivo results clearly indicate that RhaR represses the operon by binding to the operator site, which is detached by L-rhamnulose-1-phosphate formed from L-rhamnose through a sequence of isomerization by RhaA and phosphorylation by RhaB, leading to the derepression of the operon. In addition, the lacZ reporter analysis using the strains with or without the ccpA deletion under the background of rhaR disruption supported the involvement of CcpA in the carbon catabolite repression of the operon. IMPORTANCE Since L-rhamnose is a component of various plant-derived compounds, it is a potential carbon source for plant-associating bacteria. Moreover, it is suggested that L-rhamnose catabolism plays a significant role in some bacteria-plant interactions, e.g., invasion of plant pathogens and nodulation of rhizobia. Despite the physiological importance of L-rhamnose catabolism for various bacterial species, the transcriptional regulation of the relevant genes has been poorly understood, except for the regulatory system of Escherichia coli. In this study, we show that, in Bacillus subtilis, one of the plant growth-promoting rhizobacteria, the rhaEWRBMA operon for L-rhamnose catabolism is controlled by RhaR and CcpA. This regulatory system can be another standard model for better understanding the regulatory mechanisms of L-rhamnose catabolism in other bacterial species.
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Yoshida H, Yoshihara A, Teraoka M, Yamashita S, Izumori K, Kamitori S. Structure of l-rhamnose isomerase in complex with l-rhamnopyranose demonstrates the sugar-ring opening mechanism and the role of a substrate sub-binding site. FEBS Open Bio 2012; 3:35-40. [PMID: 23772372 PMCID: PMC3668531 DOI: 10.1016/j.fob.2012.11.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 11/30/2012] [Indexed: 11/26/2022] Open
Abstract
l-Rhamnose isomerase (l-RhI) catalyzes the reversible isomerization of l-rhamnose to l-rhamnulose. Previously determined X-ray structures of l-RhI showed a hydride-shift mechanism for the isomerization of substrates in a linear form, but the mechanism for opening of the sugar-ring is still unclear. To elucidate this mechanism, we determined X-ray structures of a mutant l-RhI in complex with l-rhamnopyranose and d-allopyranose. Results suggest that a catalytic water molecule, which acts as an acid/base catalyst in the isomerization reaction, is likely to be involved in pyranose-ring opening, and that a newly found substrate sub-binding site in the vicinity of the catalytic site may recognize different anomers of substrates.
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Key Words
- D327N, mutant P. stutzeril-RhI, with a substitution of Asp327 with Asn
- E. coli, Escherichia coli
- H101N, mutant P. stutzeril-RhI, with a substitution of H101 with Asn
- P. stutzeri, Pseudomonas stutzeri
- Pseudomonas stutzeri
- RNS, l-rhamnose in a linear form
- Rare sugar
- Sugar-ring opening mechanism
- X-ray structure
- l-RhI, l-rhamnose isomerase
- l-Rhamnose isomerase
- α-APS, α-d-allopyranose
- α-RPS, α-l-rhamnopyranose
- β-RPS, β-l-rhamnopyranose
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Affiliation(s)
- Hiromi Yoshida
- Life Science Research Center and Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan
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Bell JA, Ho KL, Farid R. Significant reduction in errors associated with nonbonded contacts in protein crystal structures: automated all-atom refinement with PrimeX. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2012; 68:935-52. [PMID: 22868759 PMCID: PMC3413210 DOI: 10.1107/s0907444912017453] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 04/19/2012] [Indexed: 11/12/2022]
Abstract
All-atom models are essential for many applications in molecular modeling and computational chemistry. Nonbonded atomic contacts much closer than the sum of the van der Waals radii of the two atoms (clashes) are commonly observed in such models derived from protein crystal structures. A set of 94 recently deposited protein structures in the resolution range 1.5-2.8 Å were analyzed for clashes by the addition of all H atoms to the models followed by optimization and energy minimization of the positions of just these H atoms. The results were compared with the same set of structures after automated all-atom refinement with PrimeX and with nonbonded contacts in protein crystal structures at a resolution equal to or better than 0.9 Å. The additional PrimeX refinement produced structures with reasonable summary geometric statistics and similar R(free) values to the original structures. The frequency of clashes at less than 0.8 times the sum of van der Waals radii was reduced over fourfold compared with that found in the original structures, to a level approaching that found in the ultrahigh-resolution structures. Moreover, severe clashes at less than or equal to 0.7 times the sum of atomic radii were reduced 15-fold. All-atom refinement with PrimeX produced improved crystal structure models with respect to nonbonded contacts and yielded changes in structural details that dramatically impacted on the interpretation of some protein-ligand interactions.
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Affiliation(s)
- Jeffrey A. Bell
- Schrödinger, 120 West 45th Street, 17th Floor, New York, NY 10036, USA
| | - Kenneth L. Ho
- Schrödinger, 120 West 45th Street, 17th Floor, New York, NY 10036, USA
| | - Ramy Farid
- Schrödinger, 120 West 45th Street, 17th Floor, New York, NY 10036, USA
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