Selective solubilization of chlorosome proteins in Chloroflexus aurantiacus

AbstractProteins were solubilized selectively from chlorosomes of Chloroflexus aurantiacus by electrophoretic gel filtration according to Griebenow et al. Whereas the 11 kDa and 18 kDa proteins were extracted almost completely, the remaining modified chlorosomes contained high amounts of pigment and c-protein. It was concluded that the c-protein in contradiction to the publication by Griebenow et al. is indeed localized in the interior of Chloroflexus chlorosomes

A new possible binding site for bacteriochlorophyll b in a light-harvesting polypeptide of the bacterium Ectothiorhodospira halochloris

AbstractWhole cells from Ectothiorhodospira halochloris were extracted with an organic solvent mixture. At least five small hydrophobic polypeptides representing most probably the light harvesting polypeptides were purified by gel filtration and consecutive FPLC-RP chromatography. The complete amino acid sequence of a 7.4 kDa polypeptide was determined. The polypeptide shows a three domain structure, indicative of an integral membrane protein, similar to the structure of the light-harvesting polypeptides from purple non-sulfur bacteria. Sequence homologies to the β-LHPs of purple bacteria range from 23. 1° to 36.4°. The conserved intramembrane located histidine residue of the antenna polypeptides of purple non-sulfur bacteria, assigned as the possible binding site for bacteriochlorophyll, was found to be replaced by asparagine

Metabolic Cleavage and Translocation Efficiency of Selected Cell Penetrating Peptides: A Comparative Study with Epithelial Cell Cultures

We investigated the metabolic stability of four cell penetrating peptides (CPPs), namely SAP, hCT(9-32)-br, [Pα] and [Pβ], when in contact with either subconfluent HeLa, confluent MDCK or Calu-3 epithelial cell cultures. Additionally, through analysis of their cellular translocation efficiency, we evaluated possible relations between metabolic stability and translocation efficiency. Metabolic degradation kinetics and resulting metabolites were assessed using RP-HPLC and MALDI-TOF mass spectrometry. Translocation efficiencies were determined using fluorescence-activated cell sorting (FACS) and confocal laser scanning microscopy (CLSM). Between HeLa, MDCK and Calu-3 we found the levels of proteolytic activities to be highly variable. However, for each peptide, the individual degradation patterns were quite similar. The metabolic stability of the investigated CPPs was in the order of CF-SAP = CF-hCT(9-32)-br > [Pβ]−IAF > [Pα] and we identified specific cleavage sites for each of the four peptides. Throughout, we observed higher translocation efficiencies into HeLa cells as compared to MDCK and Calu-3, corresponding to the lower state of differentiation of HeLa cell cultures. No direct relation between metabolic stability and translocation efficiency was found, indicating that metabolic stability in general is not a main limiting factor for efficient cellular translocation. Nevertheless, translocation of individual CPPs may be improved by structural modifications aiming at increased metabolic stabilit

Coagulation at the blood-electrode interface: the role of electrochemical desorption and degradation of fibrinogen

The influence of electrochemistry on the coagulation of blood on metal surfaces was demonstrated several decades ago. In particular, the application of cathodic currents resulted in reduced surface thrombogenicity, but no molecular mechanism has been so far proposed to explain this observation. In this article we used for the first time the quartz crystal microbalance with dissipation monitoring technique coupled with an electrochemical setup (EQCM-D) to study thrombosis at the blood-electrode interface. We confirmed the reduced thrombus deposition at the cathode, and we subsequently studied the effect of cathodic currents on adsorbed fibrinogen (Fg). Using EQCM and mass spectrometry, we found that upon applying currents Fg desorbed from the electrode and was electrochemically degraded. In particular, we show that the flexible N-terminus of the α-chain, containing an important polymerization site, was cleaved from the protein, thus affecting its clottability. Our work proposes a molecular mechanism that at least partially explains how cathodic currents reduce thrombosis at the blood-electrode interface and is a relevant contribution to the rational development of medical devices with reduced thrombus formation on their surface

Quantitative whole-cell MALDI-TOF MS fingerprints distinguishes human monocyte sub-populations activated by distinct microbial ligands

Conventionally, human monocyte sub-populations are classified according to surface marker expression into classical (CD14(++)CD16(-)), intermediate (CD14(++)CD16(+)) and non-classical (CD14(+)CD16(++)) lineages. The involvement of non-classical monocytes, also referred to as proinflammatory monocytes, in the pathophysiology of diseases including diabetes mellitus, atherosclerosis or Alzheimer's disease is well recognized. The development of novel high-throughput methods to capture functional states within the different monocyte lineages at the whole cell proteomic level will enable real time monitoring of disease states.; We isolated and characterized (pan-) monocytes, mostly composed of classical CD16(-) monocytes, versus autologous CD16(+) subpopulations from the blood of healthy human donors (n = 8) and compared their inflammatory properties in response to lipopolysaccharides and M.tuberculosis antigens by multiplex cytokine profiling. Following resting and in vitro antigenic stimulation, cells were recovered and subjected to whole-cell mass spectrometry analysis. This approach identified the specific presence/absence of m/z peaks and therefore potential biomarkers that can discriminate pan-monocytes from their CD16 counterparts. Furthermore, we found that semi-quantitative data analysis could capture the subtle proteome changes occurring upon microbial stimulation that differentiate resting, from lipopolysaccharides or M. tuberculosis stimulated monocytic samples.; Whole-cell mass spectrometry fingerprinting could efficiently distinguish monocytic sub-populations that arose from a same hematopoietic lineage. We also demonstrate for the first time that mass spectrometry signatures can monitor semi-quantitatively specific activation status in response to exogenous stimulation. As such, this approach stands as a fast and efficient method for the applied immunology field to assess the reactivity of potentially any immune cell types that may sustain health or promote related inflammatory diseases

The BChlc/e-binding polypeptides from chlorosomes of green photosynthetic bacteria

AbstractA 6.3 kDa polypeptide has been isolated from chlorosomes of the green photosynthetic bacterium Pelodictyon luteolum, and its complete amino acid sequence has been determined. It exhibits an overall homology of 30% to the Bchlc-binding protein of Chloroflexus aurantiacus. Preliminary results from the N-terminal sequence analyses of the analogous polypeptides isolated from Chlorobium limicola, Prosthecochloris aestuarii and chlorobium phaeovibrioides revealed a highly conserved sequence. This protein is suggested to be the Bchlc/e-binding polypeptide in the family of the Chlorobiaceae

Application of MALDI-TOF mass spectrometry and specific PCR for tracking of E. coli O157:H− strain 431/97 in Batavia lettuce

Abstract Background In this study, lettuce roots and leaves were contaminated with enterohemorrhagic Escherichia coli O157:H− strain 431/97 under greenhouse conditions. Furthermore, the internalization of strain 431/97 in lettuce roots and leaves was examined. To track the inoculated bacteria during the experiments and to differentiate them from the autochthonous microbiota, a combined protocol including matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) and PCR was established. Results At different time points after inoculation of Batavia lettuce with 5.5 × 106 cfu/mL (high inoculation level) or 3.0 × 101 cfu/mL (low inoculation level) E. coli O157:H− strain 431/97 as well as sterile 0.9% (w/v) sodium chloride solution (negative control), samples from the root and the leaf were taken and surface disinfected with gentamicin. After homogenization, microorganisms were isolated from the samples and analyzed by MALDI-TOF MS. Analysis of the root samples resulted in bacterial counts of 1.0 × 102–1.0 × 106 cfu/0.25 g depending on the inoculated viable counts and the incubation period. In the leaf samples, strain 431/97 was not detected. The investigation of the viable cell counts of E. coli O157:H− 431/97 following irrigation of the leaves resulted in bacterial counts of 102 cfu/0.25 g for the disinfected leaf samples. Conclusions Thus, the established protocol is suitable for detecting the investigated strain under greenhouse conditions in plant infection experiments. This strain may indeed survive in the soil, but did not enter the plant via the root in detectable numbers. Contrarily, viable counts exceeding the generally accepted infective dose of less than 100 cells for enterohemorrhagic E. coli were determined internalized after irrigation of the leaves. As this may pose a risk for the consumer, the present study provides a valuable set of tools for further research