FapA is an Intrinsically Disordered Chaperone for Pseudomonas Functional Amyloid FapC

Identifying interaction interface betweenPseudomonasmajor biofilm forming functional amyloid FapC and disordered chaperone FapA during fibrillation deceleration

“…56 FapA is an IDP similar to FapC based on the 2D HSQC fingerprint spectrum from the unlabeled FapA by our work here, Figure SI3, as well as recent work by others. 17 Recently it was shown that FapA dramatically affects FapC fibrilization monitored by ThT assay, but speculated that this effect was through an "NMR invisible oligomeric species" which did not affect the NMR spectra of FapC. Even though it is not straightforward to think of an IDP acting as a chaperone, the data we present here clearly shows that FapA acts as a chaperone for monomeric FapC in vitro though specific interactions during functional amyloid formation and hence suppresses FapC fibrillation.…”

“…Examples from both pathologic and functional amyloid perspectives cover a wide range of chaperone effect on amyloid fibrils, ranging from slowing down to the prevention or even to their reversal. 17,35,37,[46][47][48] CsgE was shown to slow down the fibril formation of CsgA functional amyloid. Similarly, pathologic amyloid fibril formation of aSynuclein was slowed down by HSP90 family chaperones.…”

“…6,14 These unstructured monomers common to almost all of the functional and pathologic amyloids can be studied by only a few techniques at atomic resolution, with high-resolution solution state NMR (solution NMR) spectroscopy being a powerful choice. [15][16][17] For small fragments of amyloid proteins that can be crystallized, X-Ray crystallography established the first atomic models of different systems, 3,18,19 however, longer fragments of amyloids are not crystalline. For the full-length insoluble filamentous amyloid fibrils, solid-state magicangle spinning (MAS) NMR (ssNMR) had been the only available technique to study these non-crystalline insoluble proteins until the resolution revolution by cryo electron microscopy (Cryo-EM) in the last decade.…”

“…Compared to the HSP family or other folded chaperones, FapA belongs to a unique class of proteins that are intrinsically unfolded, but still can act as a chaperone. 17 Understanding details of the molecular mechanism of FapA chaperone is crucial to develop strategies to prevent amyloid formation in biofilm context and to prevent related chronic infections.…”

Solution-state NMR Assignment and Secondary Structural Propensities of the Full-Length and Minimalistic-Truncated Prefibrillar Monomeric Form of Biofilm-Forming Functional-Amyloid FapC fromPseudomonas aeruginosa

“…It came to our attention at the time of our submission that another preprint shows the solution-state NMR signal assignment of FL FapC with different sample conditions with additives such as a chaperone. 11 No BMRB data was available at the time of our submission, and we present results solely based on our own manual NMR signal assignment work performed last year and the data is deposited to the BMRB database.…”