Sandbox Reserved 1476
From Proteopedia
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==PDB ID 3AIE== | ==PDB ID 3AIE== | ||
| - | This enzyme is a glucansucrase from ''Streptococcus mutans''.<ref name="Ito">PMID:21354427</ref> These enzymes are large and extracellularly expressed by few other bacterial species.<ref name="Leemhuis">PMID:22796091</ref> Their main function is to catalyze the production of glucose polymers from sucrose substrates.<ref name="Ito" /> These polymers comprise the dental plaque that promotes tooth decay in humans. For this reason, knowledge of the structure | + | This enzyme is a glucansucrase from ''Streptococcus mutans''.<ref name="Ito">PMID:21354427</ref> These enzymes are large and extracellularly expressed by few other bacterial species.<ref name="Leemhuis">PMID:22796091</ref> Their main function is to catalyze the production of glucose polymers from sucrose substrates.<ref name="Ito" /> These polymers comprise the dental plaque that promotes tooth decay in humans. For this reason, knowledge of the structure and function of this enzyme is critical for the development of an inhibitor in an effort to reduce the prevalence of cavities and periodontal disease. |
<StructureSection load='3aie' size='350' side='right' caption='GTF-SI of Streptococcus mutans (PDB entry [[3aie]])' scene=''> | <StructureSection load='3aie' size='350' side='right' caption='GTF-SI of Streptococcus mutans (PDB entry [[3aie]])' scene=''> | ||
==Structure== | ==Structure== | ||
| - | The structure at right can be organized into both broad regions and more defined domains. There are three main regions: N-terminal region, catalytic region, and C-terminal glucan binding region.<ref name="Ito" /> The domains are more complex. There are five total domains; however, only four are visible in this crystal structure. Each domain consists of an N-terminal and C-terminal portion of the polypeptide chain, except Domain C, which is located at the bottom of the enzyme.<ref name="Ito" /> Following the polypeptide chain from N-terminus to C-terminus would pass through the domains in the following order: V, IV, B, A, C, A, B, IV, V.<ref name="Leemhuis" /> A high degree of structural similarity exists within the GH70 family enzymes.<ref name="Leemhuis" /> | + | The structure at right can be organized into both broad regions and more defined domains. There are three main regions: N-terminal region, catalytic region, and C-terminal glucan binding region.<ref name="Ito" /> The domains are more complex. There are five total domains; however, only four are visible in this crystal structure. Each domain consists of an N-terminal and C-terminal portion of the polypeptide chain, except Domain C, which is located at the bottom of the enzyme.<ref name="Ito" /> Following the polypeptide chain from N-terminus to C-terminus would pass through the domains in the following order: V, IV, B, A, C, A, B, IV, V.<ref name="Leemhuis" /> A high degree of structural similarity exists within the GH70 family enzymes.<ref name="Leemhuis" /> |
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===Catalytic Domain=== | ===Catalytic Domain=== | ||
Domain A is regarded as the catalytic domain.<ref name="Ito" /> Within it, exists a highly conserved <scene name='80/800655/Catalytic_triad_2/1'>catalytic triad</scene>, which includes two aspartic acid residues and a general acid/base glutamate.<ref name="Ito" /> A calcium ion is also bound to help stabilize the formation of the catalytic domain.<ref name="Ito" /> | Domain A is regarded as the catalytic domain.<ref name="Ito" /> Within it, exists a highly conserved <scene name='80/800655/Catalytic_triad_2/1'>catalytic triad</scene>, which includes two aspartic acid residues and a general acid/base glutamate.<ref name="Ito" /> A calcium ion is also bound to help stabilize the formation of the catalytic domain.<ref name="Ito" /> | ||
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===Supersecondary Structure=== | ===Supersecondary Structure=== | ||
| - | This enzyme features two well-known motifs. Domain A consists of a TIM barrel.<ref name="Ito" /> It is composed of a ring of beta strands surrounded by a ring of alpha helices. Domain C contains a greek key motif, which is four antiparallel beta strands that form a sheet.<ref name="Leemhuis" / | + | This enzyme features two well-known motifs. Domain A consists of a TIM barrel.<ref name="Ito" /> It is composed of a ring of beta strands surrounded by a ring of alpha helices. Domain C contains a greek key motif, which is four antiparallel beta strands that form a sheet.<ref name="Leemhuis" /> |
== Function == | == Function == | ||
| - | The major functions of this enzyme include synthesis of glucan, a glucosylated acceptor molecule, or release of free glucose.<ref name="Monchois">PMID:10234842</ref> | + | The major functions of this enzyme include synthesis of glucan, a glucosylated acceptor molecule, or release of free glucose.<ref name="Monchois">PMID:10234842</ref> As shown in Figure 1, all of the products are released from the same active site and from a glucosyl-enzyme intermediate.<ref name="Monchois" /> The sole, natural substrate for this enzyme is sucrose.<ref name="Hamada">PMID:6446023</ref> No cofactors or energy-carriers are required for these reactions.<ref name="Monchois" /> The energy required for bond formation is solely provided by the energy released from sucrose hydrolysis.<ref name="Monchois" />This particular glucansucrase is a mutansucrase, meaning it catalyzes the formation of α(1,3) linked glucose moieties.<ref name="Ito" /> The latest research proposes that the glucose moieties are most likely added to the non-reducing end of the glucan chain.<ref name="Moulis">PMID:16864576</ref> Binding of a glucan chain to the active site may cause a conformational change within the enzyme that favors elongation of the glucan chain instead of the formation of the other products.<ref name="Monchois" /> Acceptor molecules include maltose and isomaltose.<ref name="Leemhuis" /> Free glucose may be released upon hydrolysis of the glucose-enzyme intermediate.<ref name="Leemhuis" /> |
| - | == Disease == | + | == Disease and Relevance == |
| - | Based on the enzyme's contributions to dental cavity formation, this enzyme | + | Based on the enzyme's contributions to dental cavity formation, this enzyme attractive targets for inhibition. |
Revision as of 16:43, 8 December 2018
| This Sandbox is Reserved from November 5 2018 through January 1, 2019 for use in the course "CHEM 4923: Senior Project taught by Christina R. Bourne at the University of Oklahoma, Norman, USA. This reservation includes Sandbox Reserved 1471 through Sandbox Reserved 1478. |
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PDB ID 3AIE
This enzyme is a glucansucrase from Streptococcus mutans.[1] These enzymes are large and extracellularly expressed by few other bacterial species.[2] Their main function is to catalyze the production of glucose polymers from sucrose substrates.[1] These polymers comprise the dental plaque that promotes tooth decay in humans. For this reason, knowledge of the structure and function of this enzyme is critical for the development of an inhibitor in an effort to reduce the prevalence of cavities and periodontal disease.
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