Sandbox Reserved 962: Difference between revisions
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< | <StructureSection load='1ri1' size='350' frame='true' align='right' caption='Ecm1' scene='<scene name='' /> | ||
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<scene name='60/604481/Gtg/4'>A cap analog</scene> binds to the enzyme in a pocket near AdoHcy.{{clear}} | <scene name='60/604481/Gtg/4'>A cap analog</scene> binds to the enzyme in a pocket near AdoHcy.{{clear}} | ||
<scene name='60/604481/Interaction_gtg/2'>6 amino acids</scene> (Tyr 145, Leu216, Leu217, Asp218, Ser219, Tyr284) are involded in the binding of the cap analog, more precisely they interact with guanine <scene name='60/604481/N1_n3_06_gtg/1'>N1, N3, and O6 atoms.</scene> | <scene name='60/604481/Interaction_gtg/2'>6 amino acids</scene> (Tyr 145, Leu216, Leu217, Asp218, Ser219, Tyr284) are involded in the binding of the cap analog, more precisely they interact with guanine <scene name='60/604481/N1_n3_06_gtg/1'>N1, N3, and O6 atoms.</scene> and with the guanine exocyclic 2-NH2. {{clear}} | ||
The cap makes Van der Walls contacts with side chains from <scene name='60/604481/Vdw_gtg/1'>Leu216, Leu217, Asp218, Ser219.</scene> {{clear}} | The cap makes Van der Walls contacts with side chains from <scene name='60/604481/Vdw_gtg/1'>Leu216, Leu217, Asp218, Ser219.</scene> {{clear}} | ||
GTP makes a hydrogen bond with <scene name='60/604481/Hb_gtg/1'>Tyr284</scene> and a water mediated bond with <scene name='60/604481/Water_gtg/1'>Tyr145</scene>. | GTP makes a hydrogen bond with <scene name='60/604481/Hb_gtg/1'>Tyr284</scene> and a water mediated bond with <scene name='60/604481/Water_gtg/1'>Tyr145</scene>. | ||
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{{clear}} | {{clear}} | ||
As we can see on the figure above<ref name="Hausmann S, Zheng S, Fabrega C, Schneller SW, Lima CD, Shuman S. Encephalitozoon cuniculi mRNA cap (guanine N-7) methyltransferase: methyl acceptor specificity, inhibition BY S-adenosylmethionine analogs, and structure-guided mutational analysis. J Biol Chem. 2005 May 27;280(21):20404-12. Epub 2005 Mar 9.">PMID:15760890 </ref> , the enzyme specifically binds to guanine.{{clear}} | As we can see on the figure above<ref name="Hausmann S, Zheng S, Fabrega C, Schneller SW, Lima CD, Shuman S. Encephalitozoon cuniculi mRNA cap (guanine N-7) methyltransferase: methyl acceptor specificity, inhibition BY S-adenosylmethionine analogs, and structure-guided mutational analysis. J Biol Chem. 2005 May 27;280(21):20404-12. Epub 2005 Mar 9.">PMID:15760890 </ref> , the enzyme specifically binds to guanine.{{clear}} | ||
This specificity is achieved through different recognitions. The N-1 atom of adenine is unprotonated, this prevent the interaction of adenine with Ecm1. Ecm1 contact the O6 atom of guanine and permit an additional discrimination between guanine and adenine. Moreover the fact that ITP is not a substrate for Ecm1 show that the interactions between Ecm1 and guanine exocyclic 2-NH2 are important for substrate binding. {{clear}} | This specificity is achieved through different recognitions. The N-1 atom of adenine is unprotonated, this prevent the interaction of adenine with Ecm1. Ecm1 contact the <scene name='60/604481/N1_n3_06_gtg/1'>O6 atom</scene> of guanine and permit an additional discrimination between guanine and adenine. Moreover the fact that ITP is not a substrate for Ecm1 show that the interactions between Ecm1 and guanine exocyclic 2-NH2 are important for substrate binding. {{clear}} | ||
We also remark that the methyltransferase is not able to discrminate between ribose and desoxyribose nucleoside sugars. | We also remark that the methyltransferase is not able to discrminate between ribose and desoxyribose nucleoside sugars. | ||
