The protein interactome of the citrus Huanglongbing pathogen Candidatus Liberibacter asiaticus

• Published in: Nature communications 2023-11, Vol.14 (1), p.7838-7838, Article 7838
• Main Authors: Carter, Erica W., Peraza, Orlene Guerra, Wang, Nian
• Format: Article
• Language: English
• Subjects: 49; 49/111; 631/326/1320; 631/326/41/2095; 631/326/421; 631/337/475/2290; 82/111; Bacteria; Baits; Biology; Candidatus Liberibacter asiaticus; Culture media; Flagella; Genomes; Humanities and Social Sciences; multidisciplinary; Oxidative stress; Pathogenicity; Pathogens; Prey; Protein interaction; Proteins; Quinone oxidoreductase; Quinones; Science; Science (multidisciplinary); Yeast; Yeasts
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-43648-7

The bacterium Candidatus Liberibacter asiaticus (CLas) causes citrus Huanglongbing disease. Our understanding of the pathogenicity and biology of this microorganism remains limited because CLas has not yet been cultivated in artificial media. Its genome is relatively small and encodes approximately 1136 proteins, of which 415 have unknown functions. Here, we use a high-throughput yeast-two-hybrid (Y2H) screen to identify interactions between CLas proteins, thus providing insights into their potential functions. We identify 4245 interactions between 542 proteins, after screening 916 bait and 936 prey proteins. The false positive rate of the Y2H assay is estimated to be 2.9%. Pull-down assays for nine protein-protein interactions (PPIs) likely involved in flagellar function support the robustness of the Y2H results. The average number of PPIs per node in the CLas interactome is 15.6, which is higher than the numbers previously reported for interactomes of free-living bacteria, suggesting that CLas genome reduction has been accompanied by increased protein multi-functionality. We propose potential functions for 171 uncharacterized proteins, based on the PPI results, guilt-by-association analyses, and comparison with data from other bacterial species. We identify 40 hub-node proteins, including quinone oxidoreductase and LysR, which are known to protect other bacteria against oxidative stress and might be important for CLas survival in the phloem. We expect our PPI database to facilitate research on CLas biology and pathogenicity mechanisms. Research on the biology and pathogenicity of ‘ Candidatus Liberibacter asiaticus’ (CLas), the bacterium that causes citrus Huanglongbing disease, is hampered by our inability to cultivate it in artificial media. Here, Carter et al. use a high-throughput yeast-two-hybrid screen to identify thousands of interactions between CLas proteins, thus providing insights into their potential functions.