Graduate Students Mini Symposium VIII

Microbiology Seminar Series


16:00 h Michel Oklitschek, AG Sogaard Andersen
"Identification and characterization of SopA- a novel type IV pili-dependent motility regulator in Myxococcus xanthus"

M. xanthus moves across surfaces using type IV pili-(T4P). T4P undergo cycles of extension, adhesion, and retraction, thereby pulling cells forward. While the core components of the T4P machine are conserved, the regulators that control the function of this machine are more diverse. In M. xanthus, the small GTPase MglA interacts with the HEAT domain protein SgmX to stimulate T4P formation by unknown mechanism(s). To elucidate the molecular mechanism(s) of these two proteins, we used phylogenomics and in vivo experimentation. Here, we report the identification of SopA as a novel regulator of T4P formation.

16:30 h Mariana Sanchez-Londono, AG Randau
"Characterization of the anti-plasmid and self-targeting Type IV CRISPR-Cas system in Pseudomonas oleovorans"

Type IV CRISPR-Cas systems are RNA-guided adaptive immune systems which do not contain an apparent nuclease and the substrate requirements, and interference mechanism remain enigmatic. Here, we describe the Type IV-A CRISPR-Cas system in Pseudomonas oleovorans which contains a self-target spacer in the CRISPR-array with perfect complementary to the host pilN gene. We found that the native system scans the bacterial nucleoid, activity that is strongly reduced in a strain with a deletion of the native Type IV CRISPR-array. These data suggest that this system presents natural CRISPRi-like modules that interfere with target replication in the absence of DNA degradation.

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