1f3x: Difference between revisions

[[Image:1f3x.gif|left|200px]]<br /><applet load="1f3x" size="350" color="white" frame="true" align="right" spinBox="true"  

Mammalian pyruvate kinase (PK) is a four-domain enzyme that is active as a homo-tetramer. Tissue-specific isozymes of PK exhibit distinct levels of allosteric regulation. PK expressed in muscle tissue (M1-PK) shows hyperbolic steady-state kinetics, whereas PK expressed in kidney tissue (M2-PK) displays sigmoidal kinetics. Rabbit M1 and M2-PK are isozymes whose sequences differ in only 22 out of 530 residues per subunit, and these changes are localized in an inter-subunit interface. Previous studies have shown that a single amino acid mutation to M1-PK at either the Y (S402P) or Z (T340 M) subunit interface can confer a level of allosteric regulation that is intermediate to M1-PK and M2-PK. In an effort to elucidate the roles of the inter-subunit interaction in signal transmission and the functional/structural connectivity between these interfaces, the S402P mutant of M1-PK was crystallized and its structure resolved to 2.8 A. Although the overall S402P M1-PK structure is nearly identical with the wild-type structure within experimental error, significant differences in the conformation of the backbone are found at the site of mutation along the Y interface. In addition, there is a significant change along the Z interface, namely, a loss of an inter-subunit salt-bridge between Asp177 of domain B and Arg341 of domain A of the opposing subunit. Concurrent with the loss of the salt-bridge is an increase in the degree of rotational flexibility of domain B that constitutes the active site. Comparison of previous PK structures shows a correlation between an increase in this domain movement with the loss of the Asp177: Arg341 salt-bridge. These results identify the structural linkages between the Y and Z interfaces in regulating the interconversion of conformational states of rabbit M1-PK.

1F3X is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Oryctolagus_cuniculus Oryctolagus cuniculus] with <scene name='pdbligand=K:'>K</scene>, <scene name='pdbligand=MN:'>MN</scene> and <scene name='pdbligand=PYR:'>PYR</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Pyruvate_kinase Pyruvate kinase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.1.40 2.7.1.40] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1F3X OCA].  

[[Category: Czerwinski, E W.]]

[[Category: Fox, R O.]]

[[Category: Friesen, R H.E.]]

[[Category: Lee, J C.]]

[[Category: Watowich, S J.]]

[[Category: White, M A.]]

[[Category: Wooll, J O.]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:34:32 2008''