Research Mentor and Department
Christopher Shaffer and Kathy Hafer of the Biology Department
A highly novel Streptomyces phage, Satis, was isolated from a direct environmental sample collected from outside Danforth House on the Washington University campus. Satis infects bacterial species Streptomyces lividans producing pinpoint, cloudy plaques less than 1mm in diameter. Electron microscope data shows rare atypical physical features. Rather than the common octahedral capsid shape, Satis has a prolate head with visible cross-linked hexagonal protein structure and average measurements of 285 nm by 47 nm with a long, flexible tail measuring 268 nm. Upon sequencing, it was found that Satis contains the longest phage genome discovered to date through the SEA-PHAGE program at 186,702 base pairs. The genome is quite novel in sequence, as its closest genetic match, bacteriophage Chymera, is similar across only 15.9% of the genome. This means that Satis belongs to no known previously characterized cluster and is considered a Singleton phage. The genome contains 325 protein coding genes, of which our group analyzed Gene 230 to the end of the genome. The vast majority of the genes in this section run 3’ to 5’ and compared to the other two sections, these genes seem to be the most unique in primary, secondary, and tertiary structure. Due to the novelty of Satis, functional evidence from comparative genomic analysis is sparse. We are currently in the process of a more thurough comparative genomic analysis between Satis and other Streptomyces phages, particularly phage JustBecause, another Streptomyces phage isolated by Washington University in St. Louis students in 2016 with similar morphology to Satis.