Identification of Tse8 as a Type VI secretion system toxin from Pseudomonas aeruginosa that targets the bacterial transamidosome to inhibit protein synthesis in prey cells.

The Type VI secretion system (T6SS) is a bacterial nanomachine that delivers toxic effectors to kill competitors or subvert some of their key functions. Here, we use transposon directed insertion-site sequencing to identify T6SS toxins associated with the H1-T6SS, one of the three T6SS machines found in Pseudomonas aeruginosa. This approach identified several putative toxin-immunity pairs, including Tse8-Tsi8.

Structure-function relationships underlying the dual -acetylmuramic and -acetylglucosamine specificities of the bacterial peptidoglycan deacetylase PdaC.

PdaC (PdaC) is a membrane-bound, multidomain peptidoglycan deacetylase acting on -acetylmuramic acid (MurNAc) residues and conferring lysozyme resistance to modified cell wall peptidoglycans. PdaC contains a C-terminal family 4 carbohydrate esterase (CE4) catalytic domain, but unlike other MurNAc deacetylases, PdaC also has GlcNAc deacetylase activity on chitooligosaccharides (COSs), characteristic of chitin deacetylases. To uncover the molecular basis of this dual activity, here we determined the X-ray structure of the PdaC CE4 domain at 1.

Crystallization and preliminary X-ray diffraction analysis of the N-terminal domain of Paenibacillus barcinonensis xylanase 10C containing the CBM22-1-CBM22-2 tandem.

A construct containing the CBM22-1-CBM22-2 tandem forming the N-terminal domain of Paenibacillus barcinonensis xylanase 10C (Xyn10C) has been purified and crystallized. A xylan-binding function and an affinity for mixed β-1,3/β-1,4 glucans have previously been demonstrated for some members of the CBM22 family. The sequence of the tandem is homologous to the N-terminal domains found in several thermophilic enzymes.

Crystallization and preliminary X-ray diffraction analysis of Xyn30D from Paenibacillus barcinonensis.

Xyn30D, a new member of a recently identified group of xylanases, has been purified and crystallized. Xyn30D is a bimodular enzyme composed of an N-terminal catalytic domain belonging to glycoside hydrolase family 30 (GH30) and a C-terminal family 35 carbohydrate-binding domain (CBM35) able to bind xylans and glucuronic acid. Xyn30D shares the characteristic endo mode of action described for GH30 xylanases, with the hydrolysis of the β-(1,4) bonds of xylan being directed by α-1,2-linked glucuronate moieties, which have to be placed at the -2 subsite of the xylanase active site.