Lysis

About: Lysis is a research topic. Over the lifetime, 6072 publications have been published within this topic receiving 216978 citations.

Choline-Binding Protein D (CbpD) in Streptococcus pneumoniae Is Essential for Competence-Induced Cell Lysis

Abstract: Streptococcus pneumoniae is an important human pathogen that is able to take up naked DNA from the environment by a quorum-sensing-regulated process called natural genetic transformation. This property enables members of this bacterial species to efficiently acquire new properties that may increase their ability to survive and multiply in the human host. We have previously reported that induction of the competent state in a liquid culture of Streptococcus pneumoniae triggers lysis of a subfraction of the bacterial population resulting in release of DNA. We have also proposed that such competence-induced DNA release is an integral part of natural genetic transformation that has evolved to increase the efficiency of gene transfer between pneumococci. In the present work, we have further elucidated the mechanism behind competence-induced cell lysis by identifying a putative murein hydrolase, choline-binding protein D (CbpD), as a key component of this process. By using real-time PCR to estimate the amount of extracellular DNA in competent relative to noncompetent cultures, we were able to show that competence-induced cell lysis and DNA release are strongly attenuated in a cbpD mutant. Ectopic expression of CbpD in the presence or absence of other competence proteins revealed that CbpD is essentially unable to cause cell lysis on its own but depends on at least one additional protein expressed during competence.

A Protein Antibiotic in the Phage Qβ Virion: Diversity in Lysis Targets

Abstract: A2, a capsid protein of RNA phage Qβ, is also responsible for host lysis. A2 blocked synthesis of murein precursors in vivo by inhibiting MurA, the catalyst of the committed step of murein biosynthesis. An A2-resistance mutation mapped to an exposed surface near the substrate-binding cleft of MurA. Moreover, purified Qβ virions inhibited wild-type MurA, but not the mutant MurA, in vitro. Thus, the two small phages characterized for their lysis strategy, Qβ and the small DNA phage φX174, effect host lysis by targeting different enzymes in the multistep, universally conserved pathway of cell wall biosynthesis.

Cell death versus cell survival instructed by supramolecular cohesion of nanostructures

Abstract: Many naturally occurring peptides containing cationic and hydrophobic domains have evolved to interact with mammalian cell membranes and have been incorporated into materials for non-viral gene delivery, cancer therapy, or treatment of microbial infections. Their electrostatic attraction to the negatively charged cell surface and hydrophobic interactions with the membrane lipids enable intracellular delivery or cell lysis. While the effects of hydrophobicity and cationic charge of soluble molecules on the cell membrane are well known, the interactions between materials with these molecular features and cells remain poorly understood. Here we report that varying the cohesive forces within nanofibres of supramolecular materials with nearly identical cationic and hydrophobic structure instruct cell death or cell survival. Weak intermolecular bonds promote cell death through disruption of lipid membranes, while materials reinforced by hydrogen bonds support cell viability. These findings provide new strategies to design biomaterials that interact with the cell membrane.