Location: Produce Safety and Microbiology ResearchTitle: Identification of protein biomarkers of Xylella fastidiosa using MALDI-TOF-TOF-MS/MS and top-down proteomic analysis
Submitted to: Proceedings of the ASMS Conference on Mass Spectrometry and Allied Topics
Publication Type: Proceedings
Publication Acceptance Date: 6/16/2022
Publication Date: 8/4/2022
Citation: Fagerquist, C.K., Wallis, C.M., Chen, J. 2022. Identification of protein biomarkers of Xylella fastidiosa using MALDI-TOF-TOF-MS/MS and top-down proteomic analysis. Proceedings of the ASMS Conference on Mass Spectrometry and Allied Topics. ID 310588.
Technical Abstract: Xylella fastidiosa is an aerobic gram-negative bacterium that causes Pierce’s Disease in viticulture resulting in its destruction. X. fastidiosa is transmitted by sharpshooter leafhoppers (e.g. Glassy-winged sharpshooter). A number of X. fastidiosa strains have been genomically sequenced. However, only a few proteomic studies have been performed on this plant pathogen. Using MALDI-TOF-TOF-MS, MS/MS and top-down proteomic analysis, we have identified several highly conserved proteins in two genomically sequenced X. fastidiosa subsp. fastidiosa strains: M23 (Kern county) and Stag’s Leap (Napa county), both of which were isolated in California. In addition, we have identified an outer membrane/hypothetical protein whose sequence differs between these strains and which shows variable sequence truncation at the N-terminus. MS and MS/MS data were analyzed using software developed in-house to scan in silico protein sequences derived from whole genome sequencing. Software identifications were confirmed by manual inspection. Highly conserved proteins were identified: cold-shock and/or DNA-binding proteins, chaperonin protein GroES, ribosomal protein 50S/L33 and hypothetical proteins. The protein sequences were identical in both strains. The N-terminal methionine was removed consistent with the penultimate residue rule for bacterial proteins. In addition, we identified an outer membrane/hypothetical protein (OMP/Hypo) whose sequence differed between the two strains and exhibited variable truncation of its sequence from the N-terminus. This variable sequence truncation was not observed for other identified proteins suggesting that this unusual truncation may be intrinsic to this protein structure/function. The OMP/Hypo protein has several alanine residue repeats (i.e. AA, AAA, AAAA, AAAAA, etc.) that are distributed across its primary sequence and interspersed by fourteen proline residues.