1l5n

From Proteopedia

Crystal Structure of CobT complexed with imidazole

PDB ID 1l5n

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Structural highlights

1l5n is a 1 chain structure with sequence from Salmonella enterica. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 1.9Å
Ligands:	,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

COBT_SALTY Catalyzes the synthesis of alpha-ribazole-5'-phosphate from nicotinate mononucleotide (NAMN) and 5,6-dimethylbenzimidazole (DMB).

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

Publication Abstract from PubMed

The evolution of biosynthetic pathways is difficult to reconstruct in hindsight; however, the structures of the enzymes that are involved may provide insight into their development. One enzyme in the cobalamin biosynthetic pathway that appears to have evolved from a protein with different function is L-threonine-O-3-phosphate decarboxylase (CobD) from Salmonella enterica, which is structurally similar to histidinol phosphate aminotransferase [Cheong, C. G., Bauer, C. B., Brushaber, K. R., Escalante-Semerena, J. C., and Rayment, I. (2002) Biochemistry 41, 4798-4808]. This enzyme is responsible for synthesizing (R)-1-amino-2-propanol phosphate which is the precursor for the linkage between the nucleotide loop and the corrin ring in cobalamin. To understand the relationship between this decarboxylase and the aspartate aminotransferase family to which it belongs, the structures of CobD in its apo state, the apo state complexed with the substrate, and its product external aldimine complex have been determined at 1.46, 1.8, and 1.8 A resolution, respectively. These structures show that the enzyme steers the breakdown of the external aldimine toward decarboxylation instead of amino transfer by positioning the carboxylate moiety of the substrate out of the plane of the pyridoxal ring and by placing the alpha-hydrogen out of reach of the catalytic base provided by the lysine that forms the internal aldimine. It would appear that CobD evolved from a primordial PLP-dependent aminotransferase, where the selection was based on similarities between the stereochemical properties of the substrates rather than preservation of the fate of the external aldimine. These structures provide a sequence signature for distinguishing between L-threonine-O-3-phosphate decarboxylase and histidinol phosphate aminotransferases, many of which appear to have been misannotated.

Structural studies of the L-threonine-O-3-phosphate decarboxylase (CobD) enzyme from Salmonella enterica: the apo, substrate, and product-aldimine complexes.,Cheong CG, Escalante-Semerena JC, Rayment I Biochemistry. 2002 Jul 23;41(29):9079-89. PMID:12119022^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Cheong CG, Escalante-Semerena JC, Rayment I. Structural studies of the L-threonine-O-3-phosphate decarboxylase (CobD) enzyme from Salmonella enterica: the apo, substrate, and product-aldimine complexes. Biochemistry. 2002 Jul 23;41(29):9079-89. PMID:12119022