1xx2: Difference between revisions

<StructureSection load='1xx2' size='340' side='right' caption='[[1xx2]], [[Resolution|resolution]] 1.88&Aring;' scene=''>

<table><tr><td colspan='2'>[[1xx2]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Enterobacter_cloacae Enterobacter cloacae]. This structure supersedes the now removed PDB entry [http://oca.weizmann.ac.il/oca-bin/send-pdb?obs=1&id=2blt 2blt]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XX2 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1XX2 FirstGlance]. <br>

</td></tr><tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1bls|1bls]], [[2blt|2blt]]</td></tr>

<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><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></td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1xx2 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1xx2 OCA], [http://pdbe.org/1xx2 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1xx2 RCSB], [http://www.ebi.ac.uk/pdbsum/1xx2 PDBsum]</span></td></tr>

[[http://www.uniprot.org/uniprot/AMPC_ENTCL AMPC_ENTCL]] This protein is a serine beta-lactamase with a substrate specificity for cephalosporins.  

     <scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/xx/1xx2_consurf.spt"</scriptWhenChecked>

The structure of the class C ampC beta-lactamase (cephalosporinase) from Enterobacter cloacae strain P99 has been established by x-ray crystallography to 2-A resolution and compared to a class A beta-lactamase (penicillinase) structure. The binding site for beta-lactam (penicillinase) structure. The binding site for beta-lactam antibiotics is generally more open than that in penicillinases, in agreement with the ability of the class C beta-lactamases to better bind third-generation cephalosporins. Four corresponding catalytic residues (Ser-64/70, Lys-67/73, Lys-315/234, and Tyr-150/Ser-130 in class C/A) lie in equivalent positions within 0.4 A. Significant differences in positions and accessibilities of Arg-349/244 may explain the inability of clavulanate-type inhibitors to effectively inactivate the class C beta-lactamases. Glu-166, required for deacylation of the beta-lactamoyl intermediate in class A penicillinases, has no counterpart in this cephalosporinase; the nearest candidate, Asp-217, is 10 A from the reactive Ser-64. A comparison of overall tertiary folding shows that the cephalosporinase, more than the penicillinase, is broadly similar to the ancestral beta-lactam-inhibited enzymes of bacterial cell wall synthesis. On this basis, it is proposed that the cephalosporinase is the older of the two beta-lactamases, and, therefore, that a local refolding in the active site, rather than a simple point mutation, was required for the primordial class C beta-lactamase to evolve to the class A beta-lactamase having an improved ability to catalyze the deacylation step of beta-lactam hydrolysis.

Evolution of an enzyme activity: crystallographic structure at 2-A resolution of cephalosporinase from the ampC gene of Enterobacter cloacae P99 and comparison with a class A penicillinase.,Lobkovsky E, Moews PC, Liu H, Zhao H, Frere JM, Knox JR Proc Natl Acad Sci U S A. 1993 Dec 1;90(23):11257-61. PMID:8248237<ref>PMID:8248237</ref>

*[[Beta-lactamase|Beta-lactamase]]

[[Category: Knox, J R]]

[[Category: Sun, T]]

[[Category: Ampc]]

[[Category: Serine hydrolase]]