Sandbox Reserved 321: Difference between revisions
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The primary target of the thioamide drugs PTH and ETH have been shown to be InhA <scene name='Sandbox_Reserved_321/Structural_progresion/1'>(go to original scene)</scene> in both genetic and molecular experiments<ref name ="mech of thioamide drug action"/>. Both PTH and ETH require activation by various cellular componets to form the NAD adduct that acts to inhibit InhA, and therefore connot be studied in [http://en.wikipedia.org/wiki/In_vitro in vitro]<ref name ="mech of thioamide drug action"/>. The exacct mechanism of their activation is still under speculation, however a flavin monooxygenase (EthA) has been shown to participate in ETH and PTH activation<ref name ="mech of thioamide drug action"/>. In fact, strains of ''M. tuberculosis'' that have mutations in the gene which express EthA exhibit resistance to thioamide drugs<ref name ="mech of thioamide drug action"/>. Currently studies are being carried out to determine other methods of treatment for mycobaterial infections that dont require activation by cellular constituents, due to the incerease of drug resistant cases world wide. | The primary target of the thioamide drugs PTH and ETH have been shown to be InhA <scene name='Sandbox_Reserved_321/Structural_progresion/1'>(go to original scene)</scene> in both genetic and molecular experiments<ref name ="mech of thioamide drug action"/>. Both PTH and ETH require activation by various cellular componets to form the NAD adduct that acts to inhibit InhA, and therefore connot be studied in [http://en.wikipedia.org/wiki/In_vitro in vitro]<ref name ="mech of thioamide drug action"/>. The exacct mechanism of their activation is still under speculation, however a flavin monooxygenase (EthA) has been shown to participate in ETH and PTH activation<ref name ="mech of thioamide drug action"/>. In fact, strains of ''M. tuberculosis'' that have mutations in the gene which express EthA exhibit resistance to thioamide drugs<ref name ="mech of thioamide drug action"/>. Currently studies are being carried out to determine other methods of treatment for mycobaterial infections that dont require activation by cellular constituents, due to the incerease of drug resistant cases world wide. | ||
The ETH-NAD adduct <scene name='Sandbox_Reserved_321/Ligand/1'>(EAD)</scene>, and the PTH-NAD adducts (P1H) have been found to occupy the same hydrophobic pocket of InhA as NADH and exhibit the same van der Waal interactions between K218 and M155 and the ethyl or proply group with distances of 3.3Å and 3.2Å respectively<ref name ="mech of thioamide drug action"/>. EAD or P1H binding forces | The ETH-NAD adduct <scene name='Sandbox_Reserved_321/Ligand/1'>(EAD)</scene>, and the PTH-NAD adducts (P1H) have been found to occupy the same hydrophobic pocket of InhA as NADH and exhibit the same van der Waal interactions between K218 and M155 and the ethyl or proply group with distances of 3.3Å and 3.2Å respectively<ref name ="mech of thioamide drug action"/>. EAD or P1H binding forces the rotation of F149 by 90° which causes a ring stacking interation with the pyridine ring on the adduct. In addtion π stacking interactions form between the propyl group of P1H and the ethyl group of <scene name='Sandbox_Reserved_321/Pi_stacking/1'>EAD with Y158</scene> at distance of ~3.3Å. These interations and conformational changes in InhA contribute to its inactivation. Developmentaly this is important, for InhA is no longer active an the mycolic acids nessasary in cell wall compostion of various mycobacteria will not be formed. | ||
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==The SDR Family== | ==The SDR Family== | ||
InhA can also be classified into a family of short chain dehydrogenase/reductases (SDR). This family consists of proteins exhibiting a central core with a Rossmann fold that contains a NADH binding site. There are approximately 3000 primary structures outlines in various sequence databases<ref name ="SDR">PMID:12604210</ref>. Examples of proteins in this family are listed below with links to their corresponding proteopedia page. | InhA can also be classified into a family of short chain dehydrogenase/reductases (SDR's). This family consists of proteins exhibiting a central core with a Rossmann fold that contains a NADH binding site. There are approximately 3000 primary structures outlines in various sequence databases<ref name ="SDR">PMID:12604210</ref>. Examples of proteins in this family are listed below with links to their corresponding proteopedia page. | ||
*[[1bxk]] - DTDP-glucose 4,6-dehydratase -''E. coli''<br /> | *[[1bxk]] - DTDP-glucose 4,6-dehydratase -''E. coli''<br /> | ||
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*[[1i2z]] - EcENR + NAD + imidazole derivative<br /> | *[[1i2z]] - EcENR + NAD + imidazole derivative<br /> | ||
=Additional Resources= | =Additional Resources= | ||
*[http://www.pdb.org/pdb/explore/explore.do?structureId=2H9I Mycobacterium tuberculosis InhA bound with ETH-NAD adduct in the RCSB Protein Data Bank] | *[http://www.pdb.org/pdb/explore/explore.do?structureId=2H9I Mycobacterium tuberculosis InhA bound with ETH-NAD adduct, in the RCSB Protein Data Bank] | ||
*[http://www.rcsb.org/pdb/explore/explore.do?structureId=2NTJ Mycobacterium tuberculosis InhA bound with PTH-NAD adduct, in the RCSB Protein Data Bank] | |||
*[http://www.rcsb.org/pdb/explore/explore.do?structureId=3OEW Crystal structure of wild-type InhA:NADH complex, in the RCSB Protein Data Bank] | |||
=References= | =References= | ||
<References/> | <References/> | ||
