Identifying Regions of the yuk Operon Required for YukE Secretion in Bacillus Subtilis

Pathogenic bacteria, such as Mycobacterium tuberculosis, have the ability to cause fatal infections in humans. Many of these bacteria encode a conserved Type VII Secretion System (T7SS) that previous research has implicated in their pathogenicity. The mechanisms of this secretion system and the secreted virulence factors are not well understood. Bacillus subtilis is a nonpathogenic bacterium that encodes a T7SS and secretes YukE, a homolog to the secreted virulence factors. Of the four strains of B. subtilis, 3610 can secrete YukE independent of the operon, whereas PY79, another of the four strains, is dependent on the operon for YukE secretion. This research analyzed the secretion patterns of the intermediate strains, 3610 cured and 168, to identify which two of the four strains should be compared using genetic analysis to determine the cause of PY79’s dependence on the operon for YukE secretion. Similar to 3610, 3610 cured secreted YukE independent of the operon. 168 secreted YukE in a yuk-dependent manner, similar to PY79. The results indicated an important genetic variation between 3610 and 168. Knowledge of this variation, through genetic comparison, can be applied to research on pathogenic bacteria with a T7SS to support development of new drugs and vaccines.