Solution-state NMR Assignment and Secondary Structure Analysis of the Monomeric Pseudomonas Biofilm-forming Functional Amyloid Accessory Protein FapA

Abstract

FapA is an accessory protein within the biofilm forming functional bacterial amyloid related fap-operon in Pseudomonas. We present a complete sequential assignment of 1Hamide, 13C, 13C{beta}, and 15N NMR resonances for the functional form of the monomeric soluble FapA protein, comprising amino acids between 29-152. From these observed chemical shifts, the secondary structure propensities (SSPs) were determined. FapA predominantly adopts a random coil conformation, however, we also identified small propensities for -helical and {beta}-sheet conformations. Notably, these observed SSPs are smaller compared to the ones we recently observed for the monomeric soluble FapC protein. These NMR results will provide valuable insights into the activity of FapA in functional amyloid formation and regulation, that will also aid developing strategies targeting amyloid formation within biofilms and addressing chronic infections.