#METAL ION BONDING METHIONINE FREE#

Diverse microbes (photo- and heterotrophs) import DMSP for its anti-stress properties 14, 15, 16, 17, or as a key nutrient via catabolic pathways that provide energy and 3–10% or 50–100% of bacterial carbon 2 or sulfur 18 demands, respectively. DMSP release into the environment through senescence, excretion, viral infection or grazing 11 results in ubiquitous 1-100 nM levels in seawater 12, and μM levels in marine sediment 5, 9, 13, with major microbial-driven environmental impacts. These organisms produce DMSP for physiological roles in osmoprotection, sulfur and carbon storage 6, herbivore deterrence 7, antioxidation 8, and hydrostatic pressure protection 9, or as an intermediate in toxin production 10. However, heterotrophic bacteria, abundant in marine sediment and aphotic environments, have recently also been shown to produce DMSP 4, 5. DMSP production was thought to be a largely photic and oxic process, carried out primarily by algae, corals and a few plants 3. The sulfur-containing zwitterion dimethylsulfoniopropionate (DMSP) is produced at petagram levels in Earth’s oceans annually 1, constituting up to ~10% of the fixed carbon 2. This study provides important insights into the catalytic mechanism of SMM and/or DMSP production, and proposes roles for these compounds in secondary metabolite production, and SMM cycling in diverse organisms and environments. These diverse MmtN enzymes, alongside the larger plant MMT enzyme with an N-terminus homologous to MmtN, likely utilize the same proximity and desolvation mechanism. We also identify diverse functional MmtN enzymes in potentially symbiotic archaeal Candidatus Woesearchaeota and Candidate Phyla Radiation (CPR) bacteria, and the animalcule Adineta steineri, not anticipated to produce SMM and/or DMSP. We propose that MmtN uses the proximity and desolvation mechanism for Met S-methylation with two adjacent MmtN monomers comprising the Met binding site. Here we characterize a roseobacterial MmtN, providing structural and mechanistic insights into this DMSP synthesis enzyme. Recently, diverse marine Actinobacteria, α- and γ-proteobacteria were shown to initiate DMSP synthesis via the methionine (Met) S-methyltransferase enzyme (MmtN), generating S-methyl-Met (SMM). 2009 14: 163) that Pt occupies the methionine-rich copper(I)-binding site rather than histidine-rich copper(II)-binding site in the CopC protein.Ĭopyright (c) 2009 John Wiley & Sons, Ltd.Dimethylsulfoniopropionate (DMSP) is an important marine anti-stress compound, with key roles in global nutrient cycling, chemotaxis and, potentially, climate regulation. These findings are consistent with a recent finding (Sze et al. For the histidine-containing peptides, an ion containing platinum, the auxiliary ligand, and the histidine imine was observed in many instances, thus indicating the binding of the histidine side chain to the metal, but other modes of Pt coordination (N-terminus) were also found to be competitive. For the complexes with methionine-containing peptides, a marker ion, (+), was found which is indicative of binding of Pt to the methionine side chain. The minor products in the ECD spectra of (2+) complexes do show fragmentation along the peptide backbone, but the ions observed are of the a-, b-, and y-type. In the case of the ligand terpy, which binds more strongly than dien, this weakening leads to the loss of the peptide.

#METAL ION BONDING METHIONINE FREE#

Results from ECD suggest that the free electron is captured by the metal ion thus weakening the bonds to its ligands.

Each of the (2+) complexes was subjected to electron capture dissociation (ECD), collision-induced dissociation (CID) and electron-induced dissociation (EID), while each of the (+) complexes was subjected to CID and EID. Incubation of the histidine-containing peptides (GH, HG, GGH, GHG, HGG) and methionine-containing peptides (GM, MG, GGM, GMG, MGG) with the platinum complexes (+) (A) and (+) (B) followed by electrospray ionisation (ESI) led to a number of singly and doubly charged ternary platinum peptide complexes, including (2+) and (+) (where L = the ligand terpy or dien M is a peptide).

Metal ion bonding methionine