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| | {{STRUCTURE_1cbu| PDB=1cbu | SCENE= }} | | {{STRUCTURE_1cbu| PDB=1cbu | SCENE= }} |
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| - | '''ADENOSYLCOBINAMIDE KINASE/ADENOSYLCOBINAMIDE PHOSPHATE GUANYLYLTRANSFERASE (COBU) FROM SALMONELLA TYPHIMURIUM'''
| + | ===ADENOSYLCOBINAMIDE KINASE/ADENOSYLCOBINAMIDE PHOSPHATE GUANYLYLTRANSFERASE (COBU) FROM SALMONELLA TYPHIMURIUM=== |
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| - | ==Overview==
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| - | 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.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_9601028}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 9601028 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_9601028}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Salmonella typhimurium]] | | [[Category: Salmonella typhimurium]] |
| | [[Category: Transferase]] | | [[Category: Transferase]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 12:33:40 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 20:31:35 2008'' |
Revision as of 17:31, 30 June 2008
Template:STRUCTURE 1cbu
ADENOSYLCOBINAMIDE KINASE/ADENOSYLCOBINAMIDE PHOSPHATE GUANYLYLTRANSFERASE (COBU) FROM SALMONELLA TYPHIMURIUM
Template:ABSTRACT PUBMED 9601028
About this Structure
1CBU is a Single protein structure of sequence from Salmonella typhimurium. 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
Page seeded by OCA on Mon Jun 30 20:31:35 2008
