Mapping of 3-oxoacid CoA Transferase 1 (OXCT1) Mutants
The content of this page was edited by WillF94 and smackinnon and matteoferla and admin on the 2023-08-08 09:14:13.926774.The administrators of this site take no legal responsibility for the content of this page, if you believe this page is in violation of the law, please report it.
OXCT1
The OXCT1 (SCOT1) protein structure was solved back in 2008 and can be found on the PDB with the code 3DLX . It forms a homodimer where each monomer is made up of an N-terminal domain spanning residues 40-272 and a C-terminal domain with residues 298-510. Connected by a linker region 273-297. The active site of each monomer is situated at the interface of the two domains and has a strictly conserved Glu344. This residue is an integral part of the enzyme's catalytic mechanism forming a covalent linkage to the substrate succinyl-CoA. A structure of this covalent complex from a pig heart homolog has been solved (3OXO) and illustrates a conformational change as part of the mechanism. It also identifies residues (Tyr115, Ile323, Ile325, Met402, Asn412, Gly425, Lys446) involved in the CoA-binding that are conserved in the human verison.
Mutants
There are several missense mutations reported both in literature and here that are found throughtout the SCOT protein. The mutations mostly fall into three groups: those at the interface between the two monomers, those close to the active site, and the remainder affecting the structural stability of SCOT.
Here is a list of previously described mutations (Shaquat et al. JIMD, 2013):
- V112D (wild type/mutant)
- V133E (wild type/mutant)
- A215V (wild type/mutant)
- G219E (wild type/mutant)
- V221M (wild type/mutant)
- S226N (wild type/mutant)
- P262R (wild type/mutant)
- R268C (wild type/mutant)
- R268H (wild type/mutant)
- G324E (wild type/mutant)
- L327P (wild type/mutant)
- M388V (wild type/mutant)
- V404F (wild type/mutant)
- S405P (wild type/mutant)
- L429F (wild type/mutant)
- T435N (wild type/mutant)
- C456F (wild type/mutant)
- R468C (wild type/mutant)
The mutations which we are newly reporting are:
Newly described mutations:
I373S (wild type/mutant) is close to the dimer interface, within 3 Å of the opposite monomer. It is a relatively conservative mutation however still has the potential to weaken inter-subunit interactions.
M515V (wild type/mutant) and V508A (wild type/mutant) are variants that are present within the core beta sheet of the C-terminal domain. They introduce smaller but similarly hydrophobic residues that reduce hydrophobic interactions between sidechains of residues within the core sheet.
K173E (wild type/mutant), V245F (wild type/mutant) and I270K (wild type/mutant) are all variants affecting structural stability. V245F and I270K affects the central beta sheet that forms the core of the N-terminal domain. K173E is predicted to be more moderate in effect, replacing a surface lysine that makes few interactions with a glutamate that may slightly decrease protein stability.
E280A (wild type/mutant) is found in the linker region and involves the replacement of a charged residue with a smaller, neutral one, reducing the number of hydrogen and ionic bonds between the affected position and both the N and C-terminal domain. While structure-based in silico methods predict minimal impact of this mutation on SCOT folding, sequence-based methods predict severe consequences upon mutation, consistent with a functional rather than structural role for this residue.
V437M (wild type/mutant) is found within the active site and structure-based methods predict minimal impact of on protein stability, indicating the molecular consequences of this mutation is functional rather than structural.