Bacterial Type III Secretion System Effector Proteins are Distinct between Plant Symbiotic, Plant Pathogenic and Animal Pathogenic Bacteria

: Type III secretion system (T3SS) e ff ector protein is a part of bacterial secretion systems. T3SS exists in the pathogenic and symbiotic bacteria. How the T3SS e ff ector proteins in these two classes di ff er from each other should be interesting. In this paper, we successfully discriminated T3SS e ff ector proteins between plant pathogenic, animal pathogenic and plant symbiotic bacteria based on feature vectors inferred computationally by Yahara et al. only from amino acid sequences. This suggests that these three classes of bacteria employ distinct T3SS e ff ector proteins. We also hypothesized that the feature vector proposed by Yahara et al. represents protein structure, possibly protein folds defined in Structural Classification of Proteins (SCOP) database.