Virulence in aPseudomonas syringaeStrain with a Small Repertoire of Predicted Effectors

Abstract

34Both type III effector proteins and non-ribosomal peptide toxins play important 35 roles for Pseudomonas syringae pathogenicity in host plants, but whether and how 36 these virulence pathways interact to promote infection remains unclear. Genomic 37 evidence from one clade of P. syringae suggests a tradeoff between the total number of 38 type III effector proteins and presence of syringomycin, syringopeptin, and syringolin A 39 toxins. Here we report the complete genome sequence from P. syringae CC1557, 40 which contains the lowest number of known type III effectors to date and has also 41 acquired genes similar to sequences encoding syringomycin pathways from other 42 strains. We demonstrate that this strain is pathogenic on Nicotiana benthamiana and 43 that both the type III secretion system and a new type III effector family, hopBJ1, 44 contribute to virulence. We further demonstrate that virulence activity of HopBJ1 is 45 dependent on similar catalytic sites as the E. coli CNF1 toxin. Taken together, our 46 results provide additional support for a negative correlation between type III effector 47 repertoires and the potential to produce syringomycin-like toxins while also highlighting 48 how genomic synteny and bioinformatics can be used to identify and characterize novel 49 virulence proteins. 50 51 Introduction 52

Preprinting Microbiology

“…Since the first microbiology-affiliated preprint was posted on bioRxiv in November 2013 (49), an increasing number of microbiologists are posting their unpublished work to preprint severs as an efficient method for disseminating their research prior to peer review. A number of critical concerns remain about how widespread their adoption will be, how they will be perceived by traditional journals and other scientists, and whether traditional peer review will adapt to the new scientific trends and technologies.…”