| Autor: |
Samarakoon, Vindya, Owuocha, Luckio F., Hammond, Jamie, Mitchum, Melissa G., Beamer, Lesa J. |
| Předmět: |
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| Zdroj: |
Biochemical Journal; Nov2024, Vol. 481 Issue 21, p1557-1568, 12p |
| Abstrakt: |
The enzyme serine hydroxymethyltransferase (SHMT) plays a key role in folate metabolism and is conserved in all kingdoms of life. SHMT is a pyridoxal 50 -phosphate (PLP) — dependent enzyme that catalyzes the conversion of L-serine and (6S)-tetrahydrofolate to glycine and 5,10-methylene tetrahydrofolate. Crystal structures of multiple members of the SHMT family have shown that the enzyme has a single conserved cis proline, which is located near the active site. Here, we have characterized a Pro to Ser amino acid variant (P285S) that affects this conserved cis proline in soybean SHMT8. P285S was identified as one of a set of mutations that affect the resistance of soybean to the agricultural pathogen soybean cyst nematode. We find that replacement of Pro285 by serine eliminates PLP-mediated catalytic activity of SHMT8, reduces folate binding, decreases enzyme stability, and affects the dimer-tetramer ratio of the enzyme in solution. Crystal structures at 1.9–2.2 Å resolution reveal a local reordering of the polypeptide chain that extends an α-helix and shifts a turn region into the active site. This results in a dramatically perturbed PLP-binding pose, where the ring of the cofactor is flipped by ∼180° with concomitant loss of conserved enzyme-PLP interactions. A nearby region of the polypeptide becomes disordered, evidenced by missing electron density for ∼10 residues. These structural perturbations are consistent with the loss of enzyme activity and folate binding and underscore the important role of the Pro285 cis-peptide in SHMT structure and function. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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