Zn(II) and Cd(II) complexes of AMT1/MAC1 homologous Cys/His-Rich domains : so similar yet so different

Infections caused by Candida species are becoming seriously dangerous and difficult to cure due to their sophisticated mechanisms of resistance. The host organism defends itself from the invader, e.g., by increasing the concentration of metal ions. Therefore, there is a need to understand the overall mechanisms of metal homeostasis in Candida species. One of them is associated with AMT1, an important virulence factor derived from Candida glabrata, and another with MAC1, present in Candida albicans. Both of the proteins possess a homologous Cys/His-rich domain. In our studies, we have chosen two model peptides, L680 (Ac-10ACMECVRGHRSSSCKHHE27-NH2, MAC1, Candida albicans) and L681 (Ac-10ACDSCIKSHKAAQCEHNDR28-NH2, AMT1, Candida glabrata), to analyze and compare the properties of their complexes with Zn(II) and Cd(II). We studied the stoichiometry, thermodynamic stability, and spectroscopic parameters of the complexes in a wide pH range. When competing for the metal ion in the equimolar mixture of two ligands and Cd(II)/Zn(II), L680 forms more stable complexes with Cd(II) while L681 forms more stable complexes with Zn(II) in a wide pH range. Interestingly, a Glu residue was responsible for the additional stability of Cd(II)-L680. Despite a number of scientific reports suggesting Cd(II) as an efficient surrogate of Zn(II), we showed significant differences between the Zn(II) and Cd(II) complexes of the studied peptides

Seasonal dynamics of dry matter accumulation and nutrients in a mature miscanthus × giganteus stand in the lower silesia region of poland

Funding: J.C.B. and P.R.H.R. were funded by the Biotechnology and Biological Sciences Research Council strategic programme grant on Resilient Crops (BBS/E/W/10963A01).Peer reviewedPublisher PD

The role of the RACK1 ortholog Cpc2p in modulating pheromone-induced cell cycle arrest in fission yeast

The detection and amplification of extracellular signals requires the involvement of multiple protein components. In mammalian cells the receptor of activated C kinase (RACK1) is an important scaffolding protein for signal transduction networks. Further, it also performs a critical function in regulating the cell cycle by modulating the G1/S transition. Many eukaryotic cells express RACK1 orthologs, with one example being Cpc2p in the fission yeast Schizosaccharomyces pombe. In contrast to RACK1, Cpc2p has been described to positively regulate, at the ribosomal level, cells entry into M phase. In addition, Cpc2p controls the stress response pathways through an interaction with Msa2p, and sexual development by modulating Ran1p/Pat1p. Here we describe investigations into the role, which Cpc2p performs in controlling the G protein-mediated mating response pathway. Despite structural similarity to Gβ-like subunits, Cpc2p appears not to function at the G protein level. However, upon pheromone stimulation, cells overexpressing Cpc2p display substantial cell morphology defects, disorientation of septum formation and a significantly protracted G1 arrest. Cpc2p has the potential to function at multiple positions within the pheromone response pathway. We provide a mechanistic interpretation of this novel data by linking Cpc2p function, during the mating response, with its previous described interactions with Ran1p/Pat1p. We suggest that overexpressing Cpc2p prolongs the stimulated state of pheromone-induced cells by increasing ste11 gene expression. These data indicate that Cpc2p regulates the pheromone-induced cell cycle arrest in fission yeast by delaying cells entry into S phase

The control of nitrogen metabolism in Aspergillus nidulans

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Coordination properties of the zinc domains of BigR4 and SmtB proteins in nickel systems─designation of key donors

The increasing number of antibiotic-resistant pathogens has become one of the foremost health problems of modern times. One of the most lethal and multidrug-resistant bacteria is Mycobacterium tuberculosis (Mtb), which causes tuberculosis (TB). TB continues to engulf health systems due to the significant development of bacterial multidrug-resistant strains. Mammalian immune system response to mycobacterial infection includes, but is not limited to, increasing the concentration of zinc(II) and other divalent metal ions in phagosome vesicles up to toxic levels. Metal ions are necessary for the survival and virulence of bacteria but can be highly toxic to organisms if their concentrations are not strictly controlled. Therefore, understanding the mechanisms of how bacteria use metal ions to maintain their optimum concentrations and survive under lethal environmental conditions is essential. The mycobacterial SmtB protein, one of the metal-dependent transcription regulators of the ArsR/SmtB family, dissociates from DNA in the presence of high concentrations of metals, activating the expression of metal efflux proteins. In this work, we explore the properties of α5 metal-binding domains of SmtB/BigR4 proteins (the latter being the SmtB homolog from nonpathogenic Mycobacterium smegmatis), and two mutants of BigR4 as ligands for nickel(II) ions. The study focuses on the specificity of metal–ligand interactions and describes the effect of mutations on the coordination properties of the studied systems. The results of this research reveal that the Ni(II)-BigR4 α5 species are more stable than the Ni(II)-SmtB α5 complexes. His mutations, exchanging one of the histidines for alanine, cause a decrease in the stability of Ni(II) complexes. Surprisingly, the lack of His102 resulted also in increased involvement of acidic amino acids in the coordination. The results of this study may help to understand the role of critical mycobacterial virulence factor─SmtB in metal homeostasis. Although SmtB prefers Zn(II) binding, it may also bind metal ions that prefer other coordination modes, for example, Ni(II). We characterized the properties of such complexes in order to understand the nature of mycobacterial SmtB when acting as a ligand for metal ions, given that nickel and zinc ArsR family proteins possess analogous metal-binding motifs. This may provide an introduction to the design of a new antimicrobial strategy against the pathogenic bacterium M. tuberculosis

Zn(II) and Cd(II) Complexes of AMT1/MAC1 Homologous Cys/His-Rich Domains: So Similar yet So Different

Infections caused by Candida species are becoming seriously dangerous and difficult to cure due to their sophisticated mechanisms of resistance. The host organism defends itself from the invader, e.g., by increasing the concentration of metal ions. Therefore, there is a need to understand the overall mechanisms of metal homeostasis in Candida species. One of them is associated with AMT1, an important virulence factor derived from Candida glabrata, and another with MAC1, present in Candida albicans. Both of the proteins possess a homologous Cys/His-rich domain. In our studies, we have chosen two model peptides, L680 (Ac-10ACMECVR­GHRSSS­CKHHE27-NH2, MAC1, Candida albicans) and L681 (Ac-10ACDSCI­KSHKAAQ­CEHNDR28-NH2, AMT1, Candida glabrata), to analyze and compare the properties of their complexes with Zn(II) and Cd(II). We studied the stoichiometry, thermodynamic stability, and spectroscopic parameters of the complexes in a wide pH range. When competing for the metal ion in the equimolar mixture of two ligands and Cd(II)/Zn(II), L680 forms more stable complexes with Cd(II) while L681 forms more stable complexes with Zn(II) in a wide pH range. Interestingly, a Glu residue was responsible for the additional stability of Cd(II)-L680. Despite a number of scientific reports suggesting Cd(II) as an efficient surrogate of Zn(II), we showed significant differences between the Zn(II) and Cd(II) complexes of the studied peptides

Practical ways to inspire young authors

SIGLEAvailable from British Library Document Supply Centre-DSC:98/06388 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Overexpression of cpc2 mediates its pheromone effects in a G1-dependent manner.

<p>(A) Cell morphology and size, at division (micrometers ± S.D.) for strains JY1520 (h⁻, cyr1⁻, sxa2>lacZ, rum1⁻), JY1637 (h⁻, cyr1⁻, sxa2>lacZ, rum1⁻+ oe-cpc2⁺), JY1714 (h⁻, sxa2⁻, rum1⁻) and JY1715 (h⁻, sxa2⁻, rum1⁻+oe-cpc2⁺) grown in minimal medium at 29°C and stained with calcofluor. Scale bars 10 µm. (B) Number of non-septated, septated and multiple septa containing cells for the strains JY448 (h⁻, sxa2⁻), JY1714 (h⁻, sxa2⁻, rum1⁻), JY1715 (h⁻, sxa2⁻, rum1⁻+oe-cpc2⁺), JY546 (h⁻, cyr1⁻, sxa2>lacZ), JY1520 (h⁻, cyr1⁻, sxa2>lacZ, rum1⁻ ) and JY1637 (h⁻, cyr1⁻, sxa2>lacZ, rum1⁻+oe-cpc2⁺) were determined from 400 individual cells. Values shown correspond to the percentage of the total population. Cells were stained with calcofluor white, to enable visualization of septum material. (C) Pheromone-dependent transcription for the strains JY546, JY1520, JY1637 and JY1710 (h⁻, cyr1⁻, sxa2>lacZ, rum1⁻, cpc2⁻) was determined using the sxa2>lacZ reporter. Cells were stimulated with pheromone for 16 h in minimal media and assayed for β-galactosidase production using ONPG. Activity is expressed as OD₄₂₀ units per 10⁶ cells. Values are means of triplicate determinations ± S.E.M. (D) The strains JY1520 and JY1637 were grown in minimal medium containing 10 µM of pheromone for the times indicated. Cells were harvested and fixed prior to staining with propidium iodide prior to analysis using flow cytometry (see methods). The proportion of cells exhibiting 1C or 2C DNA content was determined using FACSDiva v4.1 software for the assigned gates indicated by the blue and red shapes (E) The strains JY1520, JY1710 and JY1637 were grown to mid-exponential phase over 32 h in minimal media. Cells were then stained with calcofluor white to visualize septation (top panel) and imaged bright field microscopy (bottom panel) after 32 h exposure to pheromone. Scale bars 10 µm.</p