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Proteins always find a way

New paper on spore surface protein assembly

Oeiras, 23.04.2019

Proteins are responsible for most functions and structures inside a cell, and most processes require several of these biological molecules to localize to specific sites and to interact in a very precise way. The way proteins are recruited to fulfill their functions is a fundamental question in cell biology, and understanding the complex biological molecular machinery during spore differentiation in bacteria has been the focus of Adriano Henriques Lab (previous highlighted work in 2013, 2015 and 2016). We now know that Bacillus subtilis developing spore is covered by a protein coat formed by the ordered assembly of over 80 components. This protein-bound organelle affords protection and mediates many of the environmental interactions of spores, including with host cells. Now, researchers from Tiago Cordeiro Lab have joined efforts with Adriano Henriques Lab, with colleagues at the IGC and in the USA, and have been able to describe in molecular detail how an enzyme that introduces covalent cross-links in some of the spore surface proteins is recruited to this structure. This was an important finding because it shows that the spore transglutaminase cross-links and thereby fortifies pre-existing protein complexes through a “spotwelding activity”. The work was published in PlosGenetics.

Transglutaminase is an enzyme responsible for cross-linking lysil and glutaminyl residues in proteins. A well-known enzyme of this class is the human blood coagulation factor XIII, that is activated by a protease at the clothing site so that unwanted cross-linking reactions are prevented. Now, ITQB NOVA researchers have found that the spore transglutaminase is recruited to the spore surface by its pre-assembled substrates. It this way, the activity of the enzyme is temporally and spatially controlled, and restricted to the spore surface. The authors have also structurally characterized the transglutaminase substrate that makes the most important individual contribution to recruitment of the enzyme.

 

Original paper
PLoS Genet 15(4): e1007912. https://doi.org/10.1371/journal.pgen.1007912

Temporal and spatial regulation of protein cross-linking by a bacterial transglutaminase

Catarina G. Fernandes, Diogo Martins, Guillem Hernandez, Ana L. Sousa, Carolina Freitas, Erin M. Tranfield, Tiago N. Cordeiro, Mónica Serrano, Charles P. Moran, Jr.* and Adriano O. Henriques*

*Corresponding authors

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