View source for 5g2g


==Crystal structure of ketosteroid isomerase containing M116K mutation in the equilenin-bound form==
<StructureSection load='5g2g' size='340' side='right' caption='[[5g2g]], [[Resolution|resolution]] 1.60&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[5g2g]] is a 2 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5G2G OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=5G2G FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=EQU:EQUILENIN'>EQU</scene></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=5g2g FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5g2g OCA], [http://pdbe.org/5g2g PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=5g2g RCSB], [http://www.ebi.ac.uk/pdbsum/5g2g PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=5g2g ProSAT]</span></td></tr>
</table>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Ketosteroid isomerase (3-oxosteroid Delta5-Delta4-isomerase, KSI) from Pseudomonas putida catalyzes allylic rearrangement of the 5,6-double bond of Delta5-3-ketosteroid to 4,5-position by stereospecific intramolecular transfer of a proton. The active site of KSI is formed by several hydrophobic residues and three catalytic residues (Tyr14, Asp38, and Asp99). In this study, we investigated the role of a hydrophobic Met112 residue near the active site in the catalysis, steroid binding, and stability of KSI. Replacing Met112 with alanine (yields M112A) or leucine (M112L) decreased the kcat by 20- and 4-fold, respectively. Compared with the wild type (WT), M112A and M112L KSIs showed increased KD values for equilenin, an intermediate analogue; these changes suggest that loss of packing at position 112 might lead to unfavorable steroid binding, thereby resulting in decreased catalytic activity. Furthermore, M112A and M112L mutations reduced melting temperature (Tm) by 6.4 degrees C and 2.5 degrees C, respectively. These changes suggest that favorable packing in the core is important for the maintenance of stability in KSI. The M112K mutation decreased kcat by 2000-fold, compared with the WT. In M112K KSI structure, a new salt bridge was formed between Asp38 and Lys112. This bridge could change the electrostatic potential of Asp38, and thereby contribute to the decreased catalytic activity. The M112K mutation also decreased the stability by reducing Tm by 4.1 degrees C. Our data suggest that the Met112 residue may contribute to the catalytic activity and stability of KSI by providing favorable hydrophobic environments and compact packing in the catalytic core.

Role of conserved Met112 residue in the catalytic activity and stability of ketosteroid isomerase.,Cha HJ, Jang DS, Jeong JH, Hong BH, Yun YS, Shin EJ, Choi KY Biochim Biophys Acta. 2016 Jun 30;1864(10):1322-1327. doi:, 10.1016/j.bbapap.2016.06.016. PMID:27375051<ref>PMID:27375051</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 5g2g" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Cha, H J]]
[[Category: Jeong, J H]]
[[Category: Catalysis]]
[[Category: Conserved met112]]
[[Category: Isomerase]]
[[Category: Ketosteroid isomerase]]
[[Category: Stability]]
[[Category: Structural analysis]]