Periplasmic bacterial biomineralization of copper sulfide nanoparticles

Metal sulfides are a common group of extracellular bacterial biominerals. Only few cases of intracellular biomineralization have been reported in this group, mostly limited to greigite (Fe3S4) in magnetotactic bacteria. Here, we report the intracellular but periplasmic biomineralization of copper sulfide by the magnetotactic bacterium Desulfamplus magnetovallimortis (strain BW-1) that is known to mineralize greigite and magnetite (Fe3O4) in the cytoplasm. BW-1 produces hundreds of spherical nanoparticles, composed of 1-2 nm substructures of a poorly crystalline hexagonal copper sulfide that remains in a thermodynamically unstable state. Differential proteomics suggests that periplasmic proteins, such as a DegP-like protein and a heavy metal-binding protein, could be involved in this process. The unexpected periplasmic formation of copper sulfide nanoparticles in BW-1 reveals previously unknown possibilities for intracellular biomineralization.

Download Full-text

Comparison of localization of metallothionein in tissues of metallothionein-deficient mice

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100141585 ◽

1995 ◽

Vol 53 ◽

pp. 1042-1043

Author(s):

H. Nishimura ◽

R Nishimura ◽

D.L. Adelson ◽

A.E. Michaelska ◽

K.H.A. Choo ◽

...

Keyword(s):

Metal Binding ◽

Immunohistochemical Staining ◽

Squamous Epithelium ◽

Rabbit Antiserum ◽

Slight Modification ◽

Positive Control ◽

Heavy Metal Binding ◽

Critical Organ ◽

Metal Binding Protein ◽

Deficient Mice

Metallothionein (MT), a cysteine-rich heavy metal binding protein, has several isoforms designated from I to IV. Its major isoforms, I and II, can be induced by heavy metals like cadmium (Cd) and, are present in various organs of man and animals. Rodent testes are a critical organ to Cd and it is still a controversial matter whether MT exists in the testis although it is clear that MT is not induced by Cd in this tissue. MT-IV mRNA was found to localize within tongue squamous epithelium. Whether MT-III is present mainly glial cells or neurons has become a debatable topic. In the present study, we have utilized MT-I and II gene targeted mice and compared MT localization in various tissues from both MT-deficient mice and C57Black/6J mice (C57BL) which were used as an MT-positive control. For MT immunostaining, we have used rabbit antiserum against rat MT-I known to cross-react with mammalian MT-I and II and human MT-III. Immunohistochemical staining was conducted by the method described in the previous paper with a slight modification after the tissues were fixed in HistoChoice and embedded in paraffin.

Download Full-text

Heavy metal binding by mycorrhizal fungi

Physiologia Plantarum ◽

10.1034/j.1399-3054.1994.920224.x ◽

1994 ◽

Vol 92 (2) ◽

pp. 364-368 ◽

Cited By ~ 5

Author(s):

Ulrich Galli ◽

Hannes Schuepp ◽

Christian Brunold

Keyword(s):

Heavy Metal ◽

Metal Binding ◽

Mycorrhizal Fungi ◽

Heavy Metal Binding

Download Full-text

Primary- and secondary-structural analysis of a unique prokaryotic metallothionein from a Synechococcus sp. cyanobacterium

Biochemical Journal ◽

10.1042/bj2510691 ◽

1988 ◽

Vol 251 (3) ◽

pp. 691-699 ◽

Cited By ~ 106

Author(s):

R W Olafson ◽

W D McCubbin ◽

C M Kay

Keyword(s):

Amino Acid ◽

Metal Binding ◽

Helical Structure ◽

Basic Amino Acid ◽

Cysteine Residues ◽

Amino Acid Residues ◽

C Terminus ◽

Empirical Relations ◽

Heavy Metal Binding ◽

Synechococcus Sp

Biochemical and physiological studies of Synechococcus cyanobacteria have indicated the presence of a low-Mr heavy-metal-binding protein with marked similarity to eukaryotic metallothioneins (MTs). We report here the characterization of a Synechococcus prokaryotic MT isolated by gel-permeation and reverse-phase chromatography. The large number of variants of this molecule found during chromatographic separation could not be attributed to the presence of major isoproteins as assessed by amino acid analysis and amino acid sequencing of isoforms. Two of the latter were shown to have identical primary structures that differed substantially from the well-described eukaryotic MTs. In addition to six long-chain aliphatic residues, two aromatic residues were found adjacent to one another near the centre of the molecule, making this the most hydrophobic MT to be described. Other unusual features included a pair of histidine residues located in repeating Gly-His-Thr-Gly sequences near the C-terminus and a complete lack of association of hydroxylated residues with cysteine residues, as is commonly found in eukaryotes. Similarly, aside from a single lysine residue, no basic amino acid residues were found adjacent to cysteine residues in the sequence. Most importantly, sequence alignment analyses with mammalian, invertebrate and fungal MT sequences showed no statistically significant homology aside from the presence of Cys-Xaa-Cys structures common to all MTs. On the other hand, like other MTs, the prokaryotic molecule appears to be free of alpha-helical structure but has a considerable amount of beta-structure, as predicted by both c.d. measurements and the Chou & Fasman empirical relations. Considered together, these data suggested that some similarity between the metal-thiolate clusters of the prokaryote and eukaryote MTs may exist.

Download Full-text