Crystallographic snapshots of iterative substrate translocations during nicotianamine synthesis in archaea

Abstract

Nicotianamine (NA), a small molecule ubiquitous in plants, is an important divalent metal chelator and the main precursor of phytosiderophores. Nicotianamine synthase (NAS) is the enzyme catalyzing NA synthesis by the condensation of three aminopropyl moieties of S-adenosylmethionine (SAM) and the cyclization of one of them to form an azetidine ring. Here we report five crystal structures of an archaeal NAS from Methanothermobacter thermautotrophicus, either free or in complex with its product(s) and substrate(s). These structures reveal a two-domains fold arrangement of MtNAS, a small molecule related to NA (named here thermoNicotianamine or tNA), and an original mechanism of synthesis in a buried reaction chamber. This reaction chamber is open to the solvent through a small inlet, and a single active site allows the selective entrance of only one substrate at a time that is then processed and translocated stepwise. metal homeostasis ͉ reaction mechanism

Growth ofPseudomonas aeruginosain zinc poor environments is promoted by a nicotianamine‐related metallophore

“…Some studies have demonstrated that microbial NAS are involved in the synthesis of NA‐related molecules that may exhibit species‐specific chemical features. The archeon Methanothermobacter thermautotrophicus synthesizes a molecule denominated thermonicotianamine, deriving from the condensation of two SAM molecules and a glutamic acid residue (Dreyfus et al ., ). This molecule is very similar to NA, but lacks the azetidine ring.…”

Biosynthesis of an Opine Metallophore by Pseudomonas aeruginosa

“…We considered the possibility that NAS could incorporate two aminobutyrate moieties as in M. thermautotrophicus 15 or three as in plant NAS enzymes. 18 This would result in neutral product masses of 487.20 and 588.25 Da.…”

Vacuolar Nicotianamine Has Critical and Distinct Roles under Iron Deficiency and for Zinc Sequestration in Arabidopsis

“…Nicotianamine (NA) is a low molecular mass metal chelator molecule with high binding affinity for a range of transition metal cations. It is synthesized enzymatically from three molecules of S-adenosyl Met by NICOTIANAMINE SYNTHASEs (NASs), which have been identified in vascular plants, Neurospora crassa, and Archaea and in silico in the moss Physcomitrella patens that was reported to contain NA (Higuchi et al, 1999;Trampczynska et al, 2006;Rensing et al, 2008;Dreyfus et al, 2009;Erxleben et al, 2012). The potential use of NA as an antihypertensive drug in humans is under study (Shimizu et al, 1999).…”