Bacterial laccases: some recent advances and applications

Laccases belong to the large family of multi-copper oxidases (MCOs) that couple the one-electron oxidation of substrates with the four-electron reduction of molecular oxygen to water. Because of their high relative non-specific oxidation capacity particularly on phenols and aromatic amines as well as the lack of requirement for expensive organic cofactors, they have found application in a large number of biotechnological fields. The vast majority of studies and applications were performed using fungal laccases, but bacterial laccases show interesting properties such as optimal temperature above 50 °C, optimal pH at the neutral to alkaline range, thermal and chemical stability and increased salt tolerance. Additionally, bacterial systems benefit from a wide range of molecular biology tools that facilitates their engineering and achievement of high yields of protein production and set-up of cost-effective bioprocesses. In this review we will provide up-to-date information on the distribution and putative physiological role of bacterial laccases and highlight their distinctive structural and biochemical properties, discuss the key role of copper in the biochemical properties, discuss thermostability determinants and, finally, review biotechnological applications with a focus on catalytic mechanisms on phenolics and aromatic amines.info:eu-repo/semantics/publishedVersio

Interleukin-1 beta up-regulates iron efflux in rat C6 glioma cells through modulation of ceruloplasmin and ferroportin-1 synthesis RID A-4573-2009

A number of pathologies, including neurodegeneration and inflammation, have been associated with iron dysmetabolism in the brain. Hence, systems involved in iron homeostasis at the Cellular level have aroused considerable interest in recent years. The iron exporter ferroportin-1 (FP) and the multicopper oxidase ceruloplasmin (CP) are essential for iron efflux from cells. By using RT-PCR, we demonstrate that FP and CP gene expression is up-regulated by treatment with the pro-inflammatory cytokine IL-1beta in rat C6 cells, taken as a glial cellular model. Following stimulation with IL-1beta, a higher expression level of CP and FP was also confirmed by Western blotting. Moreover, IL-1beta has been found to increase iron efflux from C6 cells, suggesting that both proteins may play a crucial role in iron homeostasis in pathological brain conditions, such as inflammatory and/or neurodegenerative diseases. (C) 2004 Elsevier Ireland Ltd. All rights reserved

Role of External Loops of Human Ceruloplasmin in Copper Loading by ATP7B and Ccc2p RID A-4573-2009

Ceruloplasmin is a multicopper oxidase required for correct iron homeostasis. Previously, we have identified a ceruloplasmin mutant associated with the iron overload disease aceruloplasminemia, which was unable to acquire copper from themammalian pump ATP7B but could be produced in an enzymatically active form in yeast. Here, we report the expression of recombinant ceruloplasmin in the yeast Pichia pastoris and the study of the role of five surface-exposed loops in copper incorporation by comparing the efficiencies of mammalian ATP7B and yeast Ccc2p. The possibility to "mix and match" mammalian and yeast multicopper oxidases and copper ATPases can provide clues on the molecular features underlying the process of copper loading in multicopper oxidases

Ceruloplasmin impairs endothelium-dependent relaxation of rabbit aorta

This study evaluated the effects of ceruloplasmin, the copper-containing blue oxidase of vertebrate plasma, on the relaxation of rabbit aortic rings after endothelial release of nitric oxide (NO). Ceruloplasmin at physiological, i.e., micromolar, concentrations inhibited relaxation of rabbit aorta induced by endothelium-dependent agonists hire acetylcholine or ADP, whereas it was ineffective toward vasodilation due to direct stimulation of smooth muscle cells by nitroglycerin. The effect was reversible and specific for native, fully metalated ceruloplasmin, since relaxation was not impaired by the heat-treated or metal-depleted derivatives. A trapping mechanism, involving a direct interaction of NO or other NO-containing species (like nitrosothiols and iron-dinitrosyls) with the copper sites and/or with the free thiol of ceruloplasmin, could be safely excluded on the basis of spectroscopic and chemical analyses of the protein exposed to authentic NO, nitrosothiols, or iron-dinitrosyls. The data presented in this paper constitute the first evidence of impairment of the endothelium-dependent vasodilatation by a plasma protein and may shed some Light on the still uncertain physiological role of ceruloplasmin