National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Antimicrobial peptides inhibiting DNA synthesis.
Michková, Sára ; Krásný, Libor (advisor) ; Rejman, Dominik (referee)
Antimicrobial peptides (AMPs) are short amino acid sequences synthesized by a spectrum of organisms as a defence mechanism against bacteria. AMPs are divided into two groups based on their mechanisms of action - membrane disruptive AMPs and AMPs with an intracellular target. Bacteria themselves can also produce these toxins that help them compete with other strains within the same ecological niche. One such a peptide is sublancin - an AMP secreted by the soil bacterium Bacillus subtilis. Sublancin is bactericidal against Gram-positive bacteria. Although the exact mechanism of action of sublancin against bacteria is not yet well understood, it is known to target intracellular processes. It was proposed that sublancin could have a negative impact on DNA replication. This bachelor thesis first provides a brief description of DNA replication and then summarizes current knowledge about AMPs that target membrane and AMPs with intracellular targets. Detailed attention is then focused on AMPs that affect nucleic acid synthesis, a mechanism also proposed for sublancin. The final part of this work describes sublancin - its expression, structure, and possible mechanism(s) of action. Key words: antimicrobial peptide, interspecies competition, sublancin, Bacillus subtilis, DNA replication
Ricinusin {--} a new antimicrobial peptide isolated from the hard tick \kur{Ixodes ricinus}: the third member of the tick histidine-rich defense protein family.
DORŇÁKOVÁ, Veronika
New gene encoding antimicrobial protein (ricinusin) was isolated from I. ricinus. The 405 nt cDNA fragment contained a 135 aa ORF, encoding a 14.5 kDa protein with 19 aa signal peptide. Gen Bank comparison of ricinusin showed weak similarity to a new type of histidine rich antimicrobial protein with unique HEAHEAHEA repeat from Boophilus microplus and Amblyomma hebraeum. The differential gene expression was strongly induced by blood feeding in larva, nymph and adults. The site of differential expression in salivary glands and gut indicates that ricinusin is induced as a part of broad-spectrum immune response. To study the amtimicrobial capacity of ricinusin and its capatibility in clearing Borrelia burgdorferi infections, it was expressed as a His-tagged fusion protein in bacterial expression system. Analysis of the genomic organization of ricinusin gene showed that it is intronless.

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