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Elucidation of the properties and structure of the pore-forming domain of colicin U produced by bacterium Shigella boydii.
Dolejšová, Tereza
Colicin U is a protein produced by bacterium Shigella boydii. It belongs to the group of pore-forming colicins. These colicins interact with receptors in the outer membrane of bacteria closely related to a producing colicinogenic strain. After interaction with the receptor, colicin is translocated across the outer membrane and periplasm to the cytoplasmic membrane where it forms pores. Consequently, the pore formation leads to membrane depolarization and cell death. In this thesis I decided to study the pore-forming properties of colicin U and its membrane topology. It is shown that colicin U pores are formed by only one colicin molecule and they are voltage dependent. Using measurements with nonelectrolytes we estimated a theoretical inner profile of the pore and its inner diameter to be between 0.7 and 1 nm. Above that, a membrane topology of colicin U pore-forming domain (PFD) is studied. BLM measurements with biotinylated colicin U showed that a significant part of colicin's PFD was translocated to the opposite side of the membrane after the pore opening. The segment between substituted amino acids F463 and D486 was evidenced to be on the trans side of the membrane after the pore opening. Additionally, properties of peptide H1, which reflects a significant part of the first α- helix of colicin...
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Elucidation of the properties and structure of the pore-forming domain of colicin U produced by bacterium Shigella boydii.
Dolejšová, Tereza ; Fišer, Radovan (advisor) ; Krůšek, Jan (referee) ; Osička, Radim (referee)
Colicin U is a protein produced by bacterium Shigella boydii. It belongs to the group of pore-forming colicins. These colicins interact with receptors in the outer membrane of bacteria closely related to a producing colicinogenic strain. After interaction with the receptor, colicin is translocated across the outer membrane and periplasm to the cytoplasmic membrane where it forms pores. Consequently, the pore formation leads to membrane depolarization and cell death. In this thesis I decided to study the pore-forming properties of colicin U and its membrane topology. It is shown that colicin U pores are formed by only one colicin molecule and they are voltage dependent. Using measurements with nonelectrolytes we estimated a theoretical inner profile of the pore and its inner diameter to be between 0.7 and 1 nm. Above that, a membrane topology of colicin U pore-forming domain (PFD) is studied. BLM measurements with biotinylated colicin U showed that a significant part of colicin's PFD was translocated to the opposite side of the membrane after the pore opening. The segment between substituted amino acids F463 and D486 was evidenced to be on the trans side of the membrane after the pore opening. Additionally, properties of peptide H1, which reflects a significant part of the first α- helix of colicin...
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Characterization of membrane pores formed by newly discovered colicin FY from Yersinia frederiksenii
Dolejšová, Tereza ; Fišer, Radovan (advisor) ; Nunvář, Jaroslav (referee)
Colicins are toxic exocellular proteins used by Gram-negative bacteria for interspecies and intraspecies competition. The colicin FY is a pore-forming protein which was recently discovered at Masaryk university. Kolicin FY is produced by strain Yersinia frederiksenii Y27601 and is active against other strains of genus Yersinia. By comparison of aminoacid sequences of C-terminal domains of selected colicins it was proved, that colicin FY is closely related to colicin Ib (Bosák et al., 2012). In this work I was trying to create brief and integrated summary about the group of colicins from the perspective of an outer membrane traslocation mechanism, overcoming the periplasmic space up to isertion of C-terminal colicin domain into the inner membrane phospholipid bilayer. Other aim of my work was to generally summarize pore properties of known colicins and compare them with recently measured characteristics of colicin FY. Keywords: colicin, Yersinia, planar lipid membranes, membrane pore
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Characterization of membrane pores formed by newly discovered colicin FY from Yersinia frederiksenii
Dolejšová, Tereza ; Fišer, Radovan (advisor) ; Nunvář, Jaroslav (referee)
Colicins are toxic exocellular proteins used by Gram-negative bacteria for interspecies and intraspecies competition. The colicin FY is a pore-forming protein which was recently discovered at Masaryk university. Kolicin FY is produced by strain Yersinia frederiksenii Y27601 and is active against other strains of genus Yersinia. By comparison of aminoacid sequences of C-terminal domains of selected colicins it was proved, that colicin FY is closely related to colicin Ib (Bosák et al., 2012). In this work I was trying to create brief and integrated summary about the group of colicins from the perspective of an outer membrane traslocation mechanism, overcoming the periplasmic space up to isertion of C-terminal colicin domain into the inner membrane phospholipid bilayer. Other aim of my work was to generally summarize pore properties of known colicins and compare them with recently measured characteristics of colicin FY. Keywords: colicin, Yersinia, planar lipid membranes, membrane pore
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