Mechanisms of axoneme and centriole elimination in Naegleria gruberi.

The early branching eukaryote Naegleria gruberi can transform transiently from an amoeboid life form lacking centrioles and flagella to a flagellate life form where these elements are present, followed by reversion to the amoeboid state. The mechanisms imparting elimination of axonemes and centrioles during this reversion process are not known. Here, we uncover that flagella primarily fold onto the cell surface and fuse within milliseconds with the plasma membrane.

Toxin:antitoxin ratio sensing autoregulation of the module.

The family of toxin-antitoxin (TA) operons is ubiquitous in bacterial genomes and, in , is an essential component to maintain the presence of chromosome II. Here, we show that transcription of the (Vc) operon is regulated in a toxin:antitoxin ratio-dependent manner using a molecular mechanism distinct from other type II TA systems. The repressor of the operon is identified as an assembly with a 6:2 stoichiometry with three interacting ParD2 dimers bridged by two ParE2 monomers.

Entropic pressure controls the oligomerization of the Vibrio cholerae ParD2 antitoxin.

ParD2 is the antitoxin component of the parDE2 toxin-antitoxin module from Vibrio cholerae and consists of an ordered DNA-binding domain followed by an intrinsically disordered ParE-neutralizing domain. In the absence of the C-terminal intrinsically disordered protein (IDP) domain, V. cholerae ParD2 (VcParD2) crystallizes as a doughnut-shaped hexadecamer formed by the association of eight dimers.

Alternative dimerization is required for activity and inhibition of the HEPN ribonuclease RnlA.

The rnlAB toxin-antitoxin operon from Escherichia coli functions as an anti-phage defense system. RnlA was identified as a member of the HEPN (Higher Eukaryotes and Prokaryotes Nucleotide-binding domain) superfamily of ribonucleases. The activity of the toxin RnlA requires tight regulation by the antitoxin RnlB, the mechanism of which remains unknown.

The Escherichia coli RnlA-RnlB toxin-antitoxin complex: production, characterization and crystallization.

The Escherichia coli rnlAB operon encodes a toxin-antitoxin module that is involved in protection against infection by bacteriophage T4. The full-length RnlA-RnlB toxin-antitoxin complex as well as the toxin RnlA were purified to homogeneity and crystallized. When the affinity tag is placed on RnlA, RnlB is largely lost during purification and the resulting crystals exclusively comprise RnlA.

In planta expression of nanobody-based designer chicken antibodies targeting Campylobacter.

Campylobacteriosis is a widespread infectious disease, leading to a major health and economic burden. Chickens are considered as the most common infection source for humans. Campylobacter mainly multiplies in the mucus layer of their caeca.