Uba1

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The <scene name='69/695713/Uba1/1'>monomeric structure</scene> of Uba1 consists of six structural domains (IAD, AAD, FCCH, SCCH, 4HB, and UFD), four of which(AAD, FCCH, SCCH, and UFD) pack together to create a central cavity. The cavity is divided into two distinct clefts (left and right) by the SCCH/AAD linker fragment. It has been suggested that Uba1 can exist as a <scene name='69/695713/Uba1/6'>dimer</scene> in solution, with two monomers non-covalently bound. Ubiquitin binds to the cysteine located on the right cleft of Uba1 which allows for ubiquitin to orient itself relative to the active site located on the left cleft. The structure of <scene name='69/695713/Uba1_monomeric_ub/2'>ubiquitin bound to Uba1</scene> (Uba1 in grey Ub in green) results in a change in conformation that buries a significant portion of Uba1 exposed surface area. The <scene name='69/695713/Uba1_monomeric_ub_catcys_hi/1'>catalytic cysteine</scene> (Cys600) located on the SCCH domain of Uba1 forms a thioester with the C-terminus of ubiquitin. It is suggested that a significant conformation change occurs when ubiquitin binds to Uba1 due to the large distance (~35 Å) between the catalytic cysteine residue and the adenylation active site.
The <scene name='69/695713/Uba1/1'>monomeric structure</scene> of Uba1 consists of six structural domains (IAD, AAD, FCCH, SCCH, 4HB, and UFD), four of which(AAD, FCCH, SCCH, and UFD) pack together to create a central cavity. The cavity is divided into two distinct clefts (left and right) by the SCCH/AAD linker fragment. It has been suggested that Uba1 can exist as a <scene name='69/695713/Uba1/6'>dimer</scene> in solution, with two monomers non-covalently bound. Ubiquitin binds to the cysteine located on the right cleft of Uba1 which allows for ubiquitin to orient itself relative to the active site located on the left cleft. The structure of <scene name='69/695713/Uba1_monomeric_ub/2'>ubiquitin bound to Uba1</scene> (Uba1 in grey Ub in green) results in a change in conformation that buries a significant portion of Uba1 exposed surface area. The <scene name='69/695713/Uba1_monomeric_ub_catcys_hi/1'>catalytic cysteine</scene> (Cys600) located on the SCCH domain of Uba1 forms a thioester with the C-terminus of ubiquitin. It is suggested that a significant conformation change occurs when ubiquitin binds to Uba1 due to the large distance (~35 Å) between the catalytic cysteine residue and the adenylation active site.
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Aside from the catalytic site interactions there are two main interactions between ubiquitin and Uba1, a hydrophobic interface, and the polar interface between ubiquitin and first-catalytic cysteine half domain, FCCH, which contains the E1 active site cysteine. The <scene name='69/695713/Uba1_monomeric_ub_hydro/3'>hydrophobic interactions</scene> are maximized by interactions between the Phe898, Leu903, and Phe905 on Uba1(seen in magenta) and the Leu8, Ile44 and Val70(seen in red) residues on ubiquitin1. This interaction is further stabilized by a <scene name='69/695713/Uba1_monomeric_ub_8/1'>hydrogen bond</scene> between the Asn900 residue on Uba1 and the carbonyl oxygen of ubiquitin’s Leu81. The interaction between ubiquitin’s c-terminus and the FCCH domain of Uba1 relies on a deep groove formed from residues 175-265 in Uba1. Four polar residues on ubiquitin, Lys11, Thr12, Gln31, and Asp32, form hydrogen bonds with three polar residues, Arg202, Gly204, and Glu206, of Uba1 <ref name=lee> </ref>
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Aside from the catalytic site interactions there are two main interactions between ubiquitin and Uba1, a hydrophobic interface, and the polar interface between ubiquitin and first-catalytic cysteine half domain, FCCH, which contains the E1 active site cysteine. The <scene name='69/695713/Uba1_monomeric_ub_hydro/3'>hydrophobic interactions</scene> are maximized by interactions between the Phe898, Leu903, and Phe905 on Uba1(seen in magenta) and the Leu8, Ile44 and Val70(seen in red) residues on ubiquitin1. This interaction is further stabilized by a <scene name='69/695713/Uba1_monomeric_ub_8/1'>hydrogen bond</scene> between the Asn900 residue on Uba1 and the carbonyl oxygen of ubiquitin’s Leu81. The interaction between ubiquitin’s c-terminus and the FCCH domain of Uba1 relies on a deep groove formed from residues 175-265 in Uba1. Four polar residues on ubiquitin, Lys11, Thr12, Gln31, and Asp32, form hydrogen bonds with three polar residues, Arg202, Gly204, and Glu206, on Uba1 <ref name=lee> </ref>
==E2 Interactions==
==E2 Interactions==

Revision as of 23:00, 25 February 2015

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