Characterization of Cold-Shock Protein A of Antarctic <Emphasis Type="Italic">Streptomyces</Emphasis> sp. AA8321

Abstact Polar organisms should have mechanisms to survive the extremely cold environment. Four genes encoding cold-shock proteins, which are small, cold-induced bacterial proteins, have been cloned from the Antarctic bacterium Streptomyces sp. AA8321. Since the specific functions of any polar bacterial or Streptomyces cold-shock proteins have not yet been determined, we examined the role of cold-shock protein A from Streptomyces sp. AA8321 (CspA_St). Gel filtration chromatography showed that purified CspA_St exists as a homodimer under physiological conditions, and gel shift assays showed that it binds to single-stranded, but not double-stranded, DNA. Overexpression of CspA_St in Escherichia coli severely impaired the ability of the host cells to form colonies, and the cells developed an elongated morphology. Incorporation of a deoxynucleoside analogue, 5-bromo-2′-deoxyuridine, into newly synthesized DNA was also drastically diminished in CspA_St-overexpressing cells. These results suggest that CspA_St play a role in inhibition of DNA replication during cold-adaptation.     

High Performance Proteomics: 7th HUPO Brain Proteome Project Workshop March 7-9, 2007 Wellcome Trust Conference Centre, Hinxton, UK

The Wellcome Trust Conference Centre at Hinxton, UK, was the meeting place of the 7th HUPO Brain Proteome Project Workshop entitled "High Performance Proteomics". It started on Wednesday, March 7, 2007 with a steering committee meeting followed by a two days series of talks dealing with the standardization and handling of tissues, body fluids as well as of proteomics data. The presentation and accompanying vivid discussions created a picture of actual strategies and standards in recent proteomics.     

Differential analysis of Bacillus anthracis after pX01 plasmid curing and comprehensive data on Bacillus anthracis infection in macrophages and glial cells

Bacillus anthracis is a gram-positive bacterial organism responsible for anthrax. This organism has two pathogenic plasmids: pX01 and pX02. The genetic function of pX01, which comprises about 198 kb, is not known, except for a region called the pathogenic island, which contains three genes-pag, lef, and cya-that code for three toxic proteins. A 2-D difference gel electrophoresis (2-D DIGE) system was used to verify the existence of proteins controlled by the pX01 plasmid, and protein regulation data were obtained using DeCyder software. A total of 1728 proteins were identified in the wild-type strain of this organism and 1684 in the pX01 plasmid. Twenty-seven of these proteins disappeared and eight appeared when the pX01 plasmid was removed. An additional 52 proteins were downregulated and 15 were upregulated when this plasmid was removed. A total of 102 proteins have been identified using the MALDI-TOF method of analysis, including 49 whose functions are unknown. Among these, 31 participate in metabolic processes, two in cellular processes, 15 in the processing of genetic information, and five in the processing of extracellular information. Another seven proteins participate in bacterial virulence and pathogenesis. We investigated the functions of these proteins in other bacteria, particularly the B. anthracis derivative H9041. Bacterial growth differed between pX01+/pX02+ B. anthracis and its pX01-/pX02+ derivative as did the cytotoxicity of macrophages infected by pX01+/pX02+ B. anthracis and the pX01-pX02+ derivative. We also found that S100B protein levels increased in the host infected with pX01+/pX02+ B. anthracis or its pX01-/pX02+ derivative. These data suggest that the pX01 plasmid plays a key role in the regulation of protein functions in B. anthracis.     

Targeting bladder tumor cells in vivo and in the urine with a peptide identified by phage display

Bladder cancer is one of the most common tumors of the genitourinary tract. Here, we use phage display to identify a peptide that targets bladder tumor cells. A phage library containing random peptides was screened for binding to cells from human bladder tumor xenografts. Phage clones were further selected for binding to a bladder tumor cell line in culture. Six clones displaying the consensus sequence CXNXDXR(X)/(R)C showed selective binding to cells from primary human bladder cancer tissue. Of these, the CSNRDARRC sequence was selected for further study as a synthetic peptide. Fluorescein-conjugated CSNRDARRC peptide selectively bound to frozen sections of human bladder tumor tissue, whereas only negligible binding to normal bladder tissue was observed. When the fluorescent peptide was introduced into the bladder lumen, in a carcinogen-induced rat tumor model, it selectively bound to tumor epithelium. Moreover, when the peptide was intravenously injected into the tail vein, it homed to the bladder tumor but was not detectable in normal bladder and control organs. Next, we examined whether the peptide can detect tumor cells in urine. The fluorescent peptide bound to cultured bladder tumor cells but not to other types of tumor cell lines. Moreover, it bound to urinary cells of patients with bladder cancer, while showing little binding to urinary cells of patients with inflammation or healthy individuals. The CSNRDARRC peptide may be useful as a targeting moiety for selective delivery of therapeutics and as a diagnostic probe for the detection of bladder cancer.     

Co-treatment with interferon-γ and 1-methyl tryptophan ameliorates cardiac fibrosis through cardiac myofibroblasts apoptosis

Molecular and Cellular Biochemistry - Electron transfer occurs through heme-Fe across the cytochrome c protein. The current models of long range electron transfer pathways in proteins include...     

Lipase and its modulator from Pseudomonas sp. strain KFCC 10818: proline-to-glutamine substitution at position 112 induces formation of enzymatically active lipase in the absence of the modulator

A lipase gene, lipK, and a lipase modulator gene, limK, of Pseudomonas sp. strain KFCC 10818 have been cloned, sequenced, and expressed in Escherichia coli. The limK gene is located immediately downstream of the lipK gene. Enzymatically active lipase was produced only in the presence of the limK gene. The effect of the lipase modulator LimK on the expression of active lipase was similar to those of the Pseudomonas subfamily I.1 and I.2 lipase-specific foldases (Lifs). The deduced amino acid sequence of LimK shares low homology (17 to 19%) with the known Pseudomonas Lifs, suggesting that Pseudomonas sp. strain KFCC 10818 is only distantly related to the subfamily I.1 and I.2 Pseudomonas species. Surprisingly, a lipase variant that does not require LimK for its correct folding was isolated in the study to investigate the functional interaction between LipK and LimK. When expressed in the absence of LimK, the P112Q variant of LipK formed an active enzyme and displayed 63% of the activity of wild-type LipK expressed in the presence of LimK. These results suggest that the Pro(112) residue of LipK is involved in a key step of lipase folding. We expect that the novel finding of this study may contribute to future research on efficient expression or refolding of industrially important lipases and on the mechanism of lipase folding.     

Rkp1/Cpc2, a fission yeast RACK1 homolog, is involved in actin cytoskeleton organization through protein kinase C, Pck2, signaling

The Rkp1/Cpc2, a fission yeast RACK1 homolog, interacted with Pck2, one of the known PKC homologs, in vivo and in vitro. The rkp1-deletion mutants (Deltarkp1) are elongated and the pck2-deletion mutant (Deltapck2) showed abnormal morphology. The double-deletion mutant (Deltarkp1Deltapck2) showed more aberrant cell shapes and was sensitive to high salt concentration. Both Deltarkp1 and Deltapck2 cells were sensitive to latrunculin B (Lat B) which inhibits actin polymerization. The cells expressing the human RACK1 homolog complemented the latrunculin B sensitivity of Deltarkp1 indicating that human RACK1 is a functional homolog of Rkp1/Cpc2. We propose that Rkp1/Cpc2 may function as a receptor for Pck2 in the regulation of actin cytoskeleton organization during cell wall synthesis and morphogenesis of Schizosaccharomyces pombe.