3W91

crystal structure of SeMet-labeled yeast N-acetyltransferase Mpr1 L87M mutant

Summary for 3W91

• Entry DOI: 10.2210/pdb3w91/pdb
• Related: 3W6S 3W6X
• Descriptor: MPR1 protein (2 entities in total)
• Functional Keywords: antioxidant enzyme, n-acetyltransferase, transferase
• Biological source: Saccharomyces cerevisiae (yeast)
• Total number of polymer chains: 3
• Total formula weight: 80015.72

Authors

Nasuno, R.,Hirano, Y.,Itoh, T.,Hakoshima, T.,Hibi, T.,Takagi, H. (deposition date: 2013-03-23, release date: 2013-07-17, Last modification date: 2024-10-30)

Primary citation

Nasuno, R.,Hirano, Y.,Itoh, T.,Hakoshima, T.,Hibi, T.,Takagi, H.
Structural and functional analysis of the yeast N-acetyltransferase Mpr1 involved in oxidative stress tolerance via proline metabolism
Proc.Natl.Acad.Sci.USA, 110:11821-11826, 2013

PubMed Abstract: Mpr1 (sigma1278b gene for proline-analog resistance 1), which was originally isolated as N-acetyltransferase detoxifying the proline analog L-azetidine-2-carboxylate, protects yeast cells from various oxidative stresses. Mpr1 mediates the L-proline and L-arginine metabolism by acetylating L-Δ(1)-pyrroline-5-carboxylate, leading to the L-arginine-dependent production of nitric oxide, which confers oxidative stress tolerance. Mpr1 belongs to the Gcn5-related N-acetyltransferase (GNAT) superfamily, but exhibits poor sequence homology with the GNAT enzymes and unique substrate specificity. Here, we present the X-ray crystal structure of Mpr1 and its complex with the substrate cis-4-hydroxy-L-proline at 1.9 and 2.3 Å resolution, respectively. Mpr1 is folded into α/β-structure with eight-stranded mixed β-sheets and six α-helices. The substrate binds to Asn135 and the backbone amide of Asn172 and Leu173, and the predicted acetyl-CoA-binding site is located near the backbone amide of Phe138 and the side chain of Asn178. Alanine substitution of Asn178, which can interact with the sulfur of acetyl-CoA, caused a large reduction in the apparent kcat value. The replacement of Asn135 led to a remarkable increase in the apparent Km value. These results indicate that Asn178 and Asn135 play an important role in catalysis and substrate recognition, respectively. Such a catalytic mechanism has not been reported in the GNAT proteins. Importantly, the amino acid substitutions in these residues increased the L-Δ(1)-pyrroline-5-carboxylate level in yeast cells exposed to heat stress, indicating that these residues are also crucial for its physiological functions. These studies provide some benefits of Mpr1 applications, such as the breeding of industrial yeasts and the development of antifungal drugs.

PubMed: 23818613
DOI: 10.1073/pnas.1300558110

Experimental method

X-RAY DIFFRACTION (2.1 Å)