1vj7: Difference between revisions

[[Image:1vj7.gif|left|200px]]<br /><applet load="1vj7" size="350" color="white" frame="true" align="right" spinBox="true"  

Enzymes of the Rel/Spo family enable bacteria to survive prolonged periods of nutrient limitation by producing an intracellular signaling alarmone, (p)ppGpp, which triggers the so-called stringent response. Both the synthesis of (p)ppGpp from ATP and GDP(GTP), and its hydrolysis to GDP(GTP) and pyrophosphate, are catalyzed by Rel/Spo proteins. The 2.1 A crystal structure of the bifunctional catalytic fragment of the Rel/Spo homolog from Streptococcus dysgalactiae subsp. equisimilis, Rel(Seq), reveals two conformations of the enzyme corresponding to known reciprocal activity states: (p)ppGpp-hydrolase-OFF/(p)ppGpp-synthetase-ON and hydrolase-ON/synthetase-OFF. The hydrolase and synthetase domains bear remarkable similarities to the catalytic domains of the cyclic phosphodiesterase and nucleotidyltransferase superfamilies, respectively. The active sites, separated by more than 30 A, contain bound nucleotides including an unusual (p)ppGpp derivative, GDP-2':3'-cyclic monophosphate. Reciprocal regulation of the antagonistic catalytic activities, suggested by the structure, is supported by mutagenesis experiments and appears to involve ligand-induced signal transmission between the two active sites.

1VJ7 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Streptococcus_dysgalactiae_subsp._equisimilis Streptococcus dysgalactiae subsp. equisimilis] with <scene name='pdbligand=MN:'>MN</scene>, <scene name='pdbligand=GDP:'>GDP</scene> and <scene name='pdbligand=GPX:'>GPX</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1VJ7 OCA].  

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:36:00 2008''