1cbu
From Proteopedia
(New page: 200px<br /><applet load="1cbu" size="450" color="white" frame="true" align="right" spinBox="true" caption="1cbu, resolution 2.3Å" /> '''ADENOSYLCOBINAMIDE KI...) |
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| - | [[Image:1cbu.gif|left|200px]]<br /><applet load="1cbu" size=" | + | [[Image:1cbu.gif|left|200px]]<br /><applet load="1cbu" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1cbu, resolution 2.3Å" /> | caption="1cbu, resolution 2.3Å" /> | ||
'''ADENOSYLCOBINAMIDE KINASE/ADENOSYLCOBINAMIDE PHOSPHATE GUANYLYLTRANSFERASE (COBU) FROM SALMONELLA TYPHIMURIUM'''<br /> | '''ADENOSYLCOBINAMIDE KINASE/ADENOSYLCOBINAMIDE PHOSPHATE GUANYLYLTRANSFERASE (COBU) FROM SALMONELLA TYPHIMURIUM'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The X-ray structure of adenosylcobinamide kinase/adenosylcobinamide | + | The X-ray structure of adenosylcobinamide kinase/adenosylcobinamide phosphate guanylyltransferase (CobU) from Salmonella typhimurium has been determined to 2.3 A resolution. This enzyme of subunit molecular weight 19 770 plays a central role in the assembly of the nucleotide loop for adenosylcobalamin where it catalyzes both the phosphorylation of the 1-amino-2-propanol side chain of the corrin ring and the subsequent attachment of GMP to form the product adenosylcobinamide-GDP. The kinase activity is believed to be associated with a P-loop motif, whereas the transferase activity proceeds at a different site on the enzyme via a guanylyl intermediate. The enzyme was crystallized in the space group C2221 with unit cell dimensions of a = 96.4 A, b = 114.4 A, and c = 106.7 A, with three subunits per asymmetric unit. The structure reveals that the enzyme is a molecular trimer and appears somewhat like a propeller with overall molecular dimensions of approximately 64 A x 77 A x 131 A. Each subunit consists of a single domain that is dominated by a seven-stranded mixed beta-sheet flanked on either side by a total of five alpha-helices and one helical turn. Six of the seven beta-strands run parallel. The C-terminal strand lies at the edge of the sheet and runs antiparallel to the others. Interestingly, CobU displays a remarkable structural and topological similarity to the central domain of the RecA protein, although the reason for this observation is unclear. The structure contains a P-loop motif located at the base of a prominent cleft formed by the association of two subunits and is most likely the kinase active site. Each subunit of CobU contains a cis peptide bond between Glu80 and Cys81 where Glu80 faces the P-loop and might serve to coordinate the magnesium ion of the triphosphate substrate. Interestingly, His46, which is the putative site for guanylylation, lies approximately 21 A from the P-loop and is solvent-exposed. This suggests that the enzyme undergoes a conformational change when the substrates bind to bring these two active sites into closer proximity. |
==About this Structure== | ==About this Structure== | ||
| - | 1CBU is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Salmonella_typhimurium Salmonella typhimurium] with SO4 as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 1CBU is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Salmonella_typhimurium Salmonella typhimurium] with <scene name='pdbligand=SO4:'>SO4</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1CBU OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Salmonella typhimurium]] | [[Category: Salmonella typhimurium]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Escalante-Semerena, J | + | [[Category: Escalante-Semerena, J C.]] |
[[Category: Rayment, I.]] | [[Category: Rayment, I.]] | ||
| - | [[Category: Thomas, M | + | [[Category: Thomas, M G.]] |
| - | [[Category: Thompson, T | + | [[Category: Thompson, T B.]] |
[[Category: SO4]] | [[Category: SO4]] | ||
[[Category: adenosylcobinamide]] | [[Category: adenosylcobinamide]] | ||
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[[Category: transferase]] | [[Category: transferase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:04:26 2008'' |
Revision as of 10:04, 21 February 2008
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ADENOSYLCOBINAMIDE KINASE/ADENOSYLCOBINAMIDE PHOSPHATE GUANYLYLTRANSFERASE (COBU) FROM SALMONELLA TYPHIMURIUM
Overview
The X-ray structure of adenosylcobinamide kinase/adenosylcobinamide phosphate guanylyltransferase (CobU) from Salmonella typhimurium has been determined to 2.3 A resolution. This enzyme of subunit molecular weight 19 770 plays a central role in the assembly of the nucleotide loop for adenosylcobalamin where it catalyzes both the phosphorylation of the 1-amino-2-propanol side chain of the corrin ring and the subsequent attachment of GMP to form the product adenosylcobinamide-GDP. The kinase activity is believed to be associated with a P-loop motif, whereas the transferase activity proceeds at a different site on the enzyme via a guanylyl intermediate. The enzyme was crystallized in the space group C2221 with unit cell dimensions of a = 96.4 A, b = 114.4 A, and c = 106.7 A, with three subunits per asymmetric unit. The structure reveals that the enzyme is a molecular trimer and appears somewhat like a propeller with overall molecular dimensions of approximately 64 A x 77 A x 131 A. Each subunit consists of a single domain that is dominated by a seven-stranded mixed beta-sheet flanked on either side by a total of five alpha-helices and one helical turn. Six of the seven beta-strands run parallel. The C-terminal strand lies at the edge of the sheet and runs antiparallel to the others. Interestingly, CobU displays a remarkable structural and topological similarity to the central domain of the RecA protein, although the reason for this observation is unclear. The structure contains a P-loop motif located at the base of a prominent cleft formed by the association of two subunits and is most likely the kinase active site. Each subunit of CobU contains a cis peptide bond between Glu80 and Cys81 where Glu80 faces the P-loop and might serve to coordinate the magnesium ion of the triphosphate substrate. Interestingly, His46, which is the putative site for guanylylation, lies approximately 21 A from the P-loop and is solvent-exposed. This suggests that the enzyme undergoes a conformational change when the substrates bind to bring these two active sites into closer proximity.
About this Structure
1CBU is a Single protein structure of sequence from Salmonella typhimurium with as ligand. Full crystallographic information is available from OCA.
Reference
Three-dimensional structure of adenosylcobinamide kinase/adenosylcobinamide phosphate guanylyltransferase from Salmonella typhimurium determined to 2.3 A resolution,., Thompson TB, Thomas MG, Escalante-Semerena JC, Rayment I, Biochemistry. 1998 May 26;37(21):7686-95. PMID:9601028
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