2cfb
From Proteopedia
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==Overview== | ==Overview== | ||
| - | Glutamate-1-semialdehyde 2,1-aminomutase (GSAM) is the second enzyme in | + | Glutamate-1-semialdehyde 2,1-aminomutase (GSAM) is the second enzyme in the C(5) pathway of tetrapyrrole biosynthesis found in most bacteria, in archaea and in plants. It catalyzes the transamination of glutamate-1-semialdehyde to 5-aminolevulinic acid (ALA) in a pyridoxal 5'-phosphate (PLP)-dependent manner. We present the crystal structure of GSAM from the thermophilic cyanobacterium Thermosynechococcus elongatus (GSAM(Tel)) in its PLP-bound form at 2.85A resolution. GSAM(Tel) is a symmetric homodimer, whereas GSAM from Synechococcus (GSAM(Syn)) has been described as asymmetric. The symmetry of GSAM(Tel) thus challenges the previously proposed negative cooperativity between monomers of this enzyme. Furthermore, GSAM(Tel) reveals an extensive flexible region at the interface of the proposed complex of GSAM with glutamyl-tRNA reductase (GluTR), the preceding enzyme in tetrapyrrole biosynthesis. Compared to GSAM(Syn), the monomers of GSAM(Tel) are rotated away from each other along the dimerization interface by 10 degrees . The associated flexibility of GSAM may be essential for complex formation with GluTR to occur. Unexpectedly, we find that GSAM is structurally related to 5-aminolevulinate synthase (ALAS), the ALA-producing enzyme in the Shemin pathway of alpha-proteobacteria and non-plant eukaryotes. This structural relationship applies also to the corresponding subfamilies of PLP-dependent enzymes. We thus propose that the CoA-subfamily (including ALAS) and the aminotransferase subfamily II (including GSAM) are evolutionarily closely related and that ALAS may thus have evolved from GSAM. |
==About this Structure== | ==About this Structure== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Synechococcus elongatus]] | [[Category: Synechococcus elongatus]] | ||
| - | [[Category: Heinz, D | + | [[Category: Heinz, D W.]] |
[[Category: Jahn, D.]] | [[Category: Jahn, D.]] | ||
[[Category: Moser, J.]] | [[Category: Moser, J.]] | ||
| - | [[Category: Schubert, W | + | [[Category: Schubert, W D.]] |
| - | [[Category: Schulze, J | + | [[Category: Schulze, J O.]] |
[[Category: PLR]] | [[Category: PLR]] | ||
[[Category: aminotransferase]] | [[Category: aminotransferase]] | ||
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[[Category: tetrapyrrole biosynthesis]] | [[Category: tetrapyrrole biosynthesis]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:48:00 2008'' |
Revision as of 14:48, 21 February 2008
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GLUTAMATE-1-SEMIALDEHYDE 2,1-AMINOMUTASE FROM THERMOSYNECHOCOCCUS ELONGATUS
Overview
Glutamate-1-semialdehyde 2,1-aminomutase (GSAM) is the second enzyme in the C(5) pathway of tetrapyrrole biosynthesis found in most bacteria, in archaea and in plants. It catalyzes the transamination of glutamate-1-semialdehyde to 5-aminolevulinic acid (ALA) in a pyridoxal 5'-phosphate (PLP)-dependent manner. We present the crystal structure of GSAM from the thermophilic cyanobacterium Thermosynechococcus elongatus (GSAM(Tel)) in its PLP-bound form at 2.85A resolution. GSAM(Tel) is a symmetric homodimer, whereas GSAM from Synechococcus (GSAM(Syn)) has been described as asymmetric. The symmetry of GSAM(Tel) thus challenges the previously proposed negative cooperativity between monomers of this enzyme. Furthermore, GSAM(Tel) reveals an extensive flexible region at the interface of the proposed complex of GSAM with glutamyl-tRNA reductase (GluTR), the preceding enzyme in tetrapyrrole biosynthesis. Compared to GSAM(Syn), the monomers of GSAM(Tel) are rotated away from each other along the dimerization interface by 10 degrees . The associated flexibility of GSAM may be essential for complex formation with GluTR to occur. Unexpectedly, we find that GSAM is structurally related to 5-aminolevulinate synthase (ALAS), the ALA-producing enzyme in the Shemin pathway of alpha-proteobacteria and non-plant eukaryotes. This structural relationship applies also to the corresponding subfamilies of PLP-dependent enzymes. We thus propose that the CoA-subfamily (including ALAS) and the aminotransferase subfamily II (including GSAM) are evolutionarily closely related and that ALAS may thus have evolved from GSAM.
About this Structure
2CFB is a Single protein structure of sequence from Synechococcus elongatus with as ligand. Active as Glutamate-1-semialdehyde 2,1-aminomutase, with EC number 5.4.3.8 Known structural/functional Site: . Full crystallographic information is available from OCA.
Reference
Evolutionary relationship between initial enzymes of tetrapyrrole biosynthesis., Schulze JO, Schubert WD, Moser J, Jahn D, Heinz DW, J Mol Biol. 2006 May 19;358(5):1212-20. Epub 2006 Mar 10. PMID:16564539
Page seeded by OCA on Thu Feb 21 16:48:00 2008
Categories: Glutamate-1-semialdehyde 2,1-aminomutase | Single protein | Synechococcus elongatus | Heinz, D W. | Jahn, D. | Moser, J. | Schubert, W D. | Schulze, J O. | PLR | Aminotransferase | Chlorophyll biosynthesis | Isomerase | Porphyrin biosynthesis | Pyridoxal phosphate dependent | Tetrapyrrole biosynthesis
