The Structure of Maltooctaose-Bound <i>Escherichia coli</i> Branching Enzyme Suggests a Mechanism for Donor Chain Specificity
Glycogen is the primary storage polysaccharide in bacteria and animals. It is a glucose polymer linked by α-1,4 glucose linkages and branched via α-1,6-linkages, with the latter reaction catalyzed by branching enzymes. Both the length and dispensation of these branches are critical in defining the s...
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MDPI AG
2023-05-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/28/11/4377 |
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| author | Remie Fawaz Courtney Bingham Hadi Nayebi Janice Chiou Lindsey Gilbert Sung Hoon Park James H. Geiger |
| author_facet | Remie Fawaz Courtney Bingham Hadi Nayebi Janice Chiou Lindsey Gilbert Sung Hoon Park James H. Geiger |
| author_sort | Remie Fawaz |
| collection | DOAJ |
| description | Glycogen is the primary storage polysaccharide in bacteria and animals. It is a glucose polymer linked by α-1,4 glucose linkages and branched via α-1,6-linkages, with the latter reaction catalyzed by branching enzymes. Both the length and dispensation of these branches are critical in defining the structure, density, and relative bioavailability of the storage polysaccharide. Key to this is the specificity of branching enzymes because they define branch length. Herein, we report the crystal structure of the maltooctaose-bound branching enzyme from the enterobacteria <i>E. coli</i>. The structure identifies three new malto-oligosaccharide binding sites and confirms oligosaccharide binding in seven others, bringing the total number of oligosaccharide binding sites to twelve. In addition, the structure shows distinctly different binding in previously identified site I, with a substantially longer glucan chain ordered in the binding site. Using the donor oligosaccharide chain-bound <i>Cyanothece</i> branching enzyme structure as a guide, binding site I was identified as the likely binding surface for the extended donor chains that the <i>E. coli</i> branching enzyme is known to transfer. Furthermore, the structure suggests that analogous loops in branching enzymes from a diversity of organisms are responsible for branch chain length specificity. Together, these results suggest a possible mechanism for transfer chain specificity involving some of these surface binding sites. |
| first_indexed | 2024-03-11T03:01:24Z |
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| institution | Directory Open Access Journal |
| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-03-11T03:01:24Z |
| publishDate | 2023-05-01 |
| publisher | MDPI AG |
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| series | Molecules |
| spelling | doaj.art-2bf25f70d55c4b858085b5244d4e820f2023-11-18T08:15:48ZengMDPI AGMolecules1420-30492023-05-012811437710.3390/molecules28114377The Structure of Maltooctaose-Bound <i>Escherichia coli</i> Branching Enzyme Suggests a Mechanism for Donor Chain SpecificityRemie Fawaz0Courtney Bingham1Hadi Nayebi2Janice Chiou3Lindsey Gilbert4Sung Hoon Park5James H. Geiger6Department of Chemistry, Michigan State University, East Lansing, MI 48824, USADepartment of Chemistry, Michigan State University, East Lansing, MI 48824, USADepartment of Chemistry, Michigan State University, East Lansing, MI 48824, USADepartment of Chemistry, Michigan State University, East Lansing, MI 48824, USADepartment of Chemistry, Michigan State University, East Lansing, MI 48824, USADepartment of Food Service Management and Nutrition, College of Natural Sciences, Sangmyung University, Hongjidong, Jongnogu, Seoul 03016, Republic of KoreaDepartment of Chemistry, Michigan State University, East Lansing, MI 48824, USAGlycogen is the primary storage polysaccharide in bacteria and animals. It is a glucose polymer linked by α-1,4 glucose linkages and branched via α-1,6-linkages, with the latter reaction catalyzed by branching enzymes. Both the length and dispensation of these branches are critical in defining the structure, density, and relative bioavailability of the storage polysaccharide. Key to this is the specificity of branching enzymes because they define branch length. Herein, we report the crystal structure of the maltooctaose-bound branching enzyme from the enterobacteria <i>E. coli</i>. The structure identifies three new malto-oligosaccharide binding sites and confirms oligosaccharide binding in seven others, bringing the total number of oligosaccharide binding sites to twelve. In addition, the structure shows distinctly different binding in previously identified site I, with a substantially longer glucan chain ordered in the binding site. Using the donor oligosaccharide chain-bound <i>Cyanothece</i> branching enzyme structure as a guide, binding site I was identified as the likely binding surface for the extended donor chains that the <i>E. coli</i> branching enzyme is known to transfer. Furthermore, the structure suggests that analogous loops in branching enzymes from a diversity of organisms are responsible for branch chain length specificity. Together, these results suggest a possible mechanism for transfer chain specificity involving some of these surface binding sites.https://www.mdpi.com/1420-3049/28/11/4377branching enzymeglycogen biosynthesisstarchglycosyl hydrolaseGH13 |
| spellingShingle | Remie Fawaz Courtney Bingham Hadi Nayebi Janice Chiou Lindsey Gilbert Sung Hoon Park James H. Geiger The Structure of Maltooctaose-Bound <i>Escherichia coli</i> Branching Enzyme Suggests a Mechanism for Donor Chain Specificity Molecules branching enzyme glycogen biosynthesis starch glycosyl hydrolase GH13 |
| title | The Structure of Maltooctaose-Bound <i>Escherichia coli</i> Branching Enzyme Suggests a Mechanism for Donor Chain Specificity |
| title_full | The Structure of Maltooctaose-Bound <i>Escherichia coli</i> Branching Enzyme Suggests a Mechanism for Donor Chain Specificity |
| title_fullStr | The Structure of Maltooctaose-Bound <i>Escherichia coli</i> Branching Enzyme Suggests a Mechanism for Donor Chain Specificity |
| title_full_unstemmed | The Structure of Maltooctaose-Bound <i>Escherichia coli</i> Branching Enzyme Suggests a Mechanism for Donor Chain Specificity |
| title_short | The Structure of Maltooctaose-Bound <i>Escherichia coli</i> Branching Enzyme Suggests a Mechanism for Donor Chain Specificity |
| title_sort | structure of maltooctaose bound i escherichia coli i branching enzyme suggests a mechanism for donor chain specificity |
| topic | branching enzyme glycogen biosynthesis starch glycosyl hydrolase GH13 |
| url | https://www.mdpi.com/1420-3049/28/11/4377 |
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