Manganese in Biological Systems: Transport and Function

Abstract

Manganese import, transport, accumulation, sensing and control pathways are important for all organisms, and of unique importance for oxygenic photosynthetic organisms due to their role in the catalysis of water oxidation by photosystem II (PSII) complexes. In this review we will describe the general aspects of Mn biochemistry, its known roles in cellular processes and its mode of function in PSII. We will describe in detail different chemical mechanisms that have evolved to obtain and control Mn ions, especially focusing on cyanobacterial systems as an example of organisms with absolute Mn requirements that populate a wide variety of environments. We will describe the steps and mechanisms by which Mn transport is performed under Mn deficient or replete conditions. Under deficient conditions a high affinity Mn transporter is expressed and becomes functional in the cyanobacterial plasma membrane. This ATP dependent transporter must overcome a number of mechanistic problems to perform its function: bind Mn ions with high affinity and specificity at very low Mn concentrations in the possible presence of higher concentrations of similar metal ions. The Mn cluster of PSII functions within the cyanobacterial cell, yet studies suggest that it is assembled in the plasma membrane facing the periplasmic space rather than in the thylakoid membrane. The topology of the two processes, Mn transport and Mn cluster assembly, should therefore be regulated in order to insure efficient biogenesis and repair of PSII complexes. Based on the available results, we attempt to map the constraints imposed by Mn transport on PSII biogenesis events in cyanobacteria.

Serotonin–Stearic Acid Bioconjugate-Coated Completely Biodegradable Mn3O4 Nanocuboids for Hepatocellular Carcinoma Targeting

“…Numerous nanotechnology-based drug delivery systems have been developed in recent years. Among these, manganese oxide nanostructures have received a huge attraction for their potential use in the biomedical applications including controlled drug delivery, magnetic resonance imaging (MRI), hyperthermia therapy, photothermal therapy, and targeted gene delivery, among others. − Also, manganese (Mn) is an essential body component, and most Mn-based nanostructures are biocompatible and have little or no toxicity …”

“…9−16 Also, manganese (Mn) is an essential body component, and most Mn-based nanostructures are biocompatible and have little or no toxicity. 17 In this study, to improve the biocompatibility of MNCs, stearic acid (SA) was coated on the surface of nanostructures. SA is a long-chain, saturated fatty acid and FDA-approved biomolecule for biological uses.…”

Questing for homoleptic mononuclear manganese complexes with monodentate O-donor ligands

“…Manganese is a key element in biological systems, 1 being particularly relevant in the photosynthesis, [2][3][4][5][6] as well as in a diversity of catalytic processes. [7][8][9][10][11][12][13] One of the facts that makes it especially interesting is the wide range of oxidation states that it can present, varying from −III to +VII.…”

Probing the dynamic behaviour and magnetic identification of seven coordinated Mn(ii) complexes: a combined AIMD and multi-reference approach

“…In biological systems, the coordination chemistry of the Mn(II) ion is of utmost significance. [1][2][3] Mn(II) ions are also extensively utilised as probes in various biological systems, replacing Zn(II), Mg(II), or Ca(II) ions. 4,5 Due to the possible use of high-spin complexes of this metal ion as contrast-enhancing agents in magnetic resonance imaging (MRI), the stable complexation of Mn(II) ions in an aqueous solution has recently drawn significant interest.…”