A secreted endosymbiont protein essential for colonizing host cells

Computational prediction of T3SS effectors To determine which Buchnera proteins are most likely to be secreted by a T3SS, the complete proteome of Buchnera -Ap (UniProt: UP000001806 ) was run in BastionX, an online tool that predicts the likelihood of a given protein to be a substrate for bacterial secretion systems ( https://bastionx.erc.monash.edu/server.jsp ) 16 . The benchmarking parameter for v.2.0 of BastionX was selected for the run (see Supplementary Dataset 1 at Figshare 17 ). An earlier version, Bastion3, had a false positive rate of 4.1% 53 , and this rate is expected to be lower in BastionX. To determine the likelihood of SyeA orthologues from diverse Buchnera being substrates for a T3SS, a total of 103 SyeA orthologues was run in BastionX, with the common use parameter for v.2.0 selected (see Supplementary Dataset 2 at Figshare 17 ). syeA , syeB and flagellar genes in Buchnera To survey the presence and absence of syeA , syeB and flagellar basal body genes in a wide range of Buchnera strains, the genomes of Buchnera strains uploaded to NCBI GenBank were selected for comparative orthology analysis (see Supplementary Dataset 2 at Figshare 17 ). The most recently uploaded Buchnera genome from each available host aphid species (22 April 2025) was chosen. Contig- and scaffold-level assemblies were excluded. If available, the RefSeq annotation was used over the GenBank annotation. …