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Antonenko Y.N.,Moscow State University | Perevoshchikova I.V.,Moscow State University | Davydova L.I.,State Scientific Center Gosenetika | Agapov I.A.,Research Institute of Transplantology and Artificial Organs | Bogush V.G.,State Scientific Center Gosenetika
Biochimica et Biophysica Acta - Biomembranes

Recombinant analogs of spider dragline silk proteins 1F9 and 2E12 are characterized by numerous repeats consisting of hydrophobic poly-Ala blocks and Gly-rich sequences with a substantial number of positively charged amino acid residues which suggest a pronounced ability to interact with negatively charged phospholipid membranes. Actually both proteins displayed substantial binding affinity towards lipid vesicles formed of acidic lipids as measured by fluorescence correlation spectroscopy (FCS) using rhodamine-labeled conjugates of the proteins. Both proteins did not induce liposome leakage, fusion or breakdown, but were able to bring about liposome aggregation. 1F9 was more active in the induction of liposome aggregation compared to 2E12. Interestingly, 2E12 markedly decreased the rate of calcium-induced liposome fusion. Circular dichroism data showed that binding of the proteins to negatively charged phosphatidylserine liposomes provoked transition from the left-handed helix of polyproline II (PPII) type to β-structures and α-helices. The data suggested predominantly surface location of membrane bound proteins without significant perturbation of their hydrophobic core. © 2010 Elsevier B.V. Source

Rodionov D.A.,Sanford Burnham Institute for Medical Research | Rodionov D.A.,Russian Academy of Sciences | Novichkov P.S.,Lawrence Berkeley National Laboratory | Stavrovskaya E.D.,Russian Academy of Sciences | And 18 more authors.
BMC Genomics

Background: Genome-scale prediction of gene regulation and reconstruction of transcriptional regulatory networks in bacteria is one of the critical tasks of modern genomics. The Shewanella genus is comprised of metabolically versatile gamma-proteobacteria, whose lifestyles and natural environments are substantially different from Escherichia coli and other model bacterial species. The comparative genomics approaches and computational identification of regulatory sites are useful for the in silico reconstruction of transcriptional regulatory networks in bacteria.Results: To explore conservation and variations in the Shewanella transcriptional networks we analyzed the repertoire of transcription factors and performed genomics-based reconstruction and comparative analysis of regulons in 16 Shewanella genomes. The inferred regulatory network includes 82 transcription factors and their DNA binding sites, 8 riboswitches and 6 translational attenuators. Forty five regulons were newly inferred from the genome context analysis, whereas others were propagated from previously characterized regulons in the Enterobacteria and Pseudomonas spp.. Multiple variations in regulatory strategies between the Shewanella spp. and E. coli include regulon contraction and expansion (as in the case of PdhR, HexR, FadR), numerous cases of recruiting non-orthologous regulators to control equivalent pathways (e.g. PsrA for fatty acid degradation) and, conversely, orthologous regulators to control distinct pathways (e.g. TyrR, ArgR, Crp).Conclusions: We tentatively defined the first reference collection of ~100 transcriptional regulons in 16 Shewanella genomes. The resulting regulatory network contains ~600 regulated genes per genome that are mostly involved in metabolism of carbohydrates, amino acids, fatty acids, vitamins, metals, and stress responses. Several reconstructed regulons including NagR for N-acetylglucosamine catabolism were experimentally validated in S. oneidensis MR-1. Analysis of correlations in gene expression patterns helps to interpret the reconstructed regulatory network. The inferred regulatory interactions will provide an additional regulatory constrains for an integrated model of metabolism and regulation in S. oneidensis MR-1. © 2011 Rodionov et al; licensee BioMed Central Ltd. Source

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