9rpk

Apo structure of Arabidopsis thaliana nicotinate mononucleotide adenylyltransferase

spinqualitylabelsall models 9rpk, resolution 2.15Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9rpk is a 1 chain structure with sequence from Arabidopsis thaliana. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.15Å Ligands: NA Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function NMNAT_ARATH Catalyzes the formation of NAD(+) from nicotinamide mononucleotide (NMN) and ATP. Can also use the deamidated form; nicotinic acid mononucleotide (NaMN) as substrate.[UniProtKB:Q9HAN9] Publication Abstract from PubMed The pyridine nucleotide adenylyltransferase (PNAT) enzyme family is crucial for the synthesis of NAD, a pivotal cofactor in cellular metabolism. PNATs catalyze the transfer of an AMP moiety from ATP to either nicotinate mononucleotide (NaMN), forming nicotinate adenine dinucleotide, the immediate precursor to NAD, or to nicotinamide mononucleotide (NMN), directly yielding NAD. This enzyme family exhibits modular substrate specificity, comprising strictly NaMN-selective (bacterial NadD), NMN-selective (bacterial NadR and NadM), or bifunctional (mammalian PNAT and archaeal NadM). While Arabidopsis thaliana PNAT has been ambiguously annotated as bifunctional, our detailed kinetic analysis definitively establishes its strict NaMN preference, analogous to bacterial NadD. By integrating bioinformatics and X-ray crystallography of the enzyme in its apo and NaMN-bound forms, we elucidate the structural basis for NaMN selectivity, which differs from bacterial NadD. In plants, a positively charged residue (Arg106 in A. thaliana NaMN adenylyltransferase, NaMNAT) ensures NaMN specificity by counteracting the negative charge of the nicotinate moiety. Site-directed mutagenesis confirms the essential role of Arg106 in NaMN recognition and catalysis. Our findings support the extension of this functional assignment across Archaeoplastida. Furthermore, phylogenetic analysis reveals the complex and intertwined evolution of bacterial and plant NaMNATs, shaped by ancient gene transfers from cyanobacteria. Arabidopsis thaliana nicotinate mononucleotide adenylyltransferase: unveiling the molecular determinants and evolutionary origin of nicotinic acid mononucleotide recognition.,Sorci L, Cianci M, Fortunato C, Gasparrini M, Raffaelli N Int J Biol Macromol. 2025 Oct 16;331(Pt 1):148370. doi: , 10.1016/j.ijbiomac.2025.148370. PMID:41109367 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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