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81.
82.
Loss of Colicinogeny in Escherichia coli Strains Infected by Certain Resistance Factors 总被引:2,自引:1,他引:1 下载免费PDF全文
The original observation that in wild-type colicinogenic Escherichia coli strains the introduction of some R factors abolish their colicin production was studied in certain col(+) strains bearing well-defined col factors. Two resistance (R) factors were used and introduced by conjugation in these strains, namely the 222 factor of Watanabe and a Salmonella typhimurium ST factor (coding for resistance to streptomycin and tetracycline only). The introduction of above mentioned R factors abolished the colicin production of col(+) strains most probably by elimination of col factors. All col factors, however, were not equally susceptible to elimination by the R factors tested, since colicin production in ML strains was abolished by infection by the 222 factor but not by the R factor of S. typhimurium ST, which is able to eliminate other col factors. 相似文献
83.
Multiple competition reactions for RPA order the assembly of the DNA polymerase delta holoenzyme. 下载免费PDF全文
Processive extension of DNA in eukaryotes requires three factors to coordinate their actions. First, DNA polymerase alpha-primase synthesizes the primed site. Then replication factor C loads a proliferating cell nuclear antigen (PCNA) clamp onto the primer. Following this, DNA polymerase delta assembles with PCNA for processive extension. This report shows that these proteins each bind the primed site tightly and trade places in a highly coordinated fashion such that the primer terminus is never left free of protein. Replication protein A (RPA), the single-stranded DNA-binding protein, forms a common touchpoint for each of these proteins and they compete with one another for it. Thus these protein exchanges are driven by competition-based protein switches in which two proteins vie for contact with RPA. 相似文献
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85.
Geert Zegels Geert AA Van Raemdonck Edmond P Coen Wiebren AA Tjalma Xaveer WM Van Ostade 《Proteome science》2009,7(1):17-16
Background
Cervical-vaginal fluid (CVF) plays an important role in the prevention of gynecological infections, although little is known about the contribution of CVF proteins to the immunity of the lower female genital tract. In order to analyze the protein composition of human CVF, we used CVF samples that are routinely collected during colposcopy, but are usually discarded. Since these samples are available in large quantities we aimed to analyze their usefulness for proteomics experiments. The samples were analyzed using different prefractionation techniques (ultrafiltration and C4(RP)-LC protein separation) followed by C18(RP)-LC peptide separation and identification by MALDI-TOF-TOF mass spectrometry. To determine the reproducibility of this proteomics platform we analyzed three technical replicates. Using spectral counting, protein abundances were estimated in a semiquantitative way. We also compared the results obtained in this study with those from previous studies derived from patients with different physiological conditions in order to determine an overlapping protein set. 相似文献86.
Vera Kozjak-Pavlovic Elke A. Dian-Lothrop Michael Meinecke Oliver Kepp Katharina Ross Krishnaraj Rajalingam Anke Harsman Eva Hauf Volker Brinkmann Dirk Günther Ines Herrmann Robert Hurwitz Joachim Rassow Richard Wagner Thomas Rudel 《PLoS pathogens》2009,5(10)
The bacterial PorB porin, an ATP-binding β-barrel protein of pathogenic Neisseria gonorrhoeae, triggers host cell apoptosis by an unknown mechanism. PorB is targeted to and imported by host cell mitochondria, causing the breakdown of the mitochondrial membrane potential (ΔΨm). Here, we show that PorB induces the condensation of the mitochondrial matrix and the loss of cristae structures, sensitizing cells to the induction of apoptosis via signaling pathways activated by BH3-only proteins. PorB is imported into mitochondria through the general translocase TOM but, unexpectedly, is not recognized by the SAM sorting machinery, usually required for the assembly of β-barrel proteins in the mitochondrial outer membrane. PorB integrates into the mitochondrial inner membrane, leading to the breakdown of ΔΨm. The PorB channel is regulated by nucleotides and an isogenic PorB mutant defective in ATP-binding failed to induce ΔΨm loss and apoptosis, demonstrating that dissipation of ΔΨm is a requirement for cell death caused by neisserial infection. 相似文献
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88.
AA Smith 《Biotechnic & histochemistry》2014,89(3):215-219
One can find the optimal antibody dilution for immunostaining by repeated staining on the same tissue section by using a less dilute antibody for each attempt. Using secondary antibody and horseradish peroxidase conjugated to a dextran polymer, a section stained repeatedly with several dilutions of antibody appears as good as a section stained with only the last dilution. 相似文献
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90.
Estimating medical costs with censored data 总被引:6,自引:0,他引:6