3 years ago

Deamidation Slows Curli Amyloid-Protein Aggregation

Deamidation Slows Curli Amyloid-Protein Aggregation
Michael L. Gross, Qin Shu, Carl Frieden, Hanliu Wang
Nonenzymatic deamidation of asparagine and glutamine in peptides and proteins is a frequent modification both in vivo and in vitro. The biological effect is not completely understood, but it is often associated with protein degradation and loss of biological function. Here we describe the deamidation of CsgA, the major protein subunit of curli, which are important proteinaceous components of biofilms. CsgA has a high content of Asn and Gln, a feature seen in a few proteins that self-aggregate. We have implemented an approach to monitor deamidation rapidly by following the globally centroid mass shift, providing guidance for studies at the residue level. From the global mass measurement, we identified, using LC-MS/MS, extensive deamidation of several Asn residues and discovered three “Asn–Gly” sites to be the hottest spots for deamidation. The fibrillization of deamidated CsgA was measured using thioflavin T (ThT) fluorescence, circular dichroism (CD), and a previously reported hydrogen–deuterium exchange (HDX) platform. Deamidated proteins exhibit a longer lag phase and lower final ThT fluorescence, strongly suggesting slower and less amyloid fibril formation. CD spectra show that extensively deamidated CsgA remains unstructured and loses its ability to form amyloids. Mass-spectrometry-based HDX also shows that deamidated CsgA aggregates more slowly than wild-type CsgA. Taken together, the results show that deamidation of CsgA slows its fibrillization and disrupts its function, suggesting an opportunity to modulate CsgA fibrillization and affect curli and biofilm formation.

Publisher URL: http://dx.doi.org/10.1021/acs.biochem.7b00241

DOI: 10.1021/acs.biochem.7b00241

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.