1zg4: Difference between revisions

Revision as of 17:34, 3 May 2008

TEM1 beta lactamase

OverviewOverview

One of the best-studied examples of a class A beta-lactamase is Escherichia coli TEM-1 beta-lactamase. In this class of enzymes, the active-site serine residue takes on the role of a nucleophile and carries out beta-lactam hydrolysis. Here, the structures of the wild-type and the S70G enzyme determined to 1.55 and 2.1 A, respectively, are presented. In contrast to the previously reported 1.8 A structure, the active site of the wild-type enzyme (1.55 A) structure does not contain sulfate and Ser70 appears to be in the deprotonated form. The X-ray crystal structure of the S70G mutant has an altered Ser130 side-chain conformation that influences the positions of water molecules in the active site. This change allows an additional water molecule to be positioned similarly to the serine hydroxyl in the wild-type enzyme. The structure of the mutant enzyme suggests that this water molecule can assume the role of an active-site nucleophile and carry out noncovalent catalysis. The drop in activity in the mutant enzyme is comparable to the drop observed in an analogous mutation of the nucleophilic serine in alkaline phosphatase, suggesting common chemical principles in the utilization of nucleophilic serine in the active site of different enzymes.

About this StructureAbout this Structure

1ZG4 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

ReferenceReference

Structure of the wild-type TEM-1 beta-lactamase at 1.55 A and the mutant enzyme Ser70Ala at 2.1 A suggest the mode of noncovalent catalysis for the mutant enzyme., Stec B, Holtz KM, Wojciechowski CL, Kantrowitz ER, Acta Crystallogr D Biol Crystallogr. 2005 Aug;61(Pt 8):1072-9. Epub 2005, Jul 20. PMID:16041072 Page seeded by OCA on Sat May 3 17:34:43 2008

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OCA

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 [[Image:1zg4.gif|left|200px]]
- {{Structure
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+The line below this paragraph, containing "STRUCTURE_1zg4", creates the "Structure Box" on the page.
-|SITE=
+You may change the PDB parameter (which sets the PDB file loaded into the applet)
-|LIGAND=
+or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
-|ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/Beta-lactamase Beta-lactamase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.2.6 3.5.2.6] </span>
+or leave the SCENE parameter empty for the default display.
-|GENE= bla ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 Escherichia coli])
+-->
-|DOMAIN=
+{{STRUCTURE_1zg4|  PDB=1zg4  |  SCENE=  }}
-|RELATEDENTRY=[[1zg6|1ZG6]]
-|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1zg4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1zg4 OCA], [http://www.ebi.ac.uk/pdbsum/1zg4 PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1zg4 RCSB]</span>
-}}
 '''TEM1 beta lactamase'''
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 [[Category: Stec, B.]]
 [[Category: Wojciechowski, C L.]]
-[[Category: hydrolase]]
+[[Category: Hydrolase]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May  3 17:34:43 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Mar 31 01:35:34 2008''