News

PhD candidate Amal Yahya successfully defended her thesis on July 3, 2023 and now is Dr. Yahya! Dr. Yahya will return this summer to her native Saudi Arabia, where she will become an assistant professor near Riyadh and teach clinical technicians. We are so proud of how far she has come and will miss her presence in the lab.

Dr. Cabeen was promoted to Associate Professor with Tenure on July 1, 2023, together with his colleague Dr. Karen Wozniak down the hall. Congratulations!

Former postdoc Dr. Simon Underhill and PhD candidate Somalisa Pan published a big project in which they examined the nitrogen-related phosphotransfer system (Nitro-PTS) in P. aeruginosa in unprecedented detail. Mary Erdmann, a talented undergraduate working with Soma, was also a coauthor. The team showed that unphosphorylated PtsN, which was previously implicated in lowering biofilm formation, is not sufficient on its own to reduce biofilm formation. They also showed that PtsN can be phosphorylated by a different enzyme I, FruB, but only in the absence of PtsO. PtsP also appears to be able to directly phosphorylate PtsN. Finally, using transcriptomics, they discover new systems that appear to be regulated by the Nitro-PTS, including production of a siderophore (pyoverdine) and express of Type III secretion. Congratulations Simon, Soma, and Mary! The paper is available in the Journal of Bacteriology at https://doi.org/10.1128/jb.00453-22 (may require a journal subscription).

PhD candidate Chris Hamm successfully defended his thesis on April 12, 2023 and now is Dr. Hamm! The good doctor has a great postdoc lined up at the University of Alabama-Birmingham, where he has also been awarded a competitive, NIH-funded MERIT fellowship that will also give him the opportunity to design a course and get teaching experience in parallel with his research. Chris is the first PhD to graduate from the Cabeen lab--we are so proud of you, Chris! He will begin his postdoc in July 2023.

PhD candidate Amal Yahya combined a huge amout of genetic work and phenotypic assays to explore new modes of biofilm regulation in P. aeruginosa. She and her undergraduate mentees Sophie and William showed that a number of genes that were differentially regulated in a deletion of 16550 (which shows decreased biofilm formation) largely do not impact biofilm formation but do impact motility. She also unexpectedly uncovered RecA as a biofilm-impacting gene and showed that both functions of RecA (SOS activation and recombination) appear important for wild-type biofilm levels. This work is published in Microbiollogy Spectrum from ASM and is available in open-access online at https://doi.org/10.1128/spectrum.03774-22.

Dr. Cabeen took home the 2022 College of Arts and Sciences Junior Faculty Award for Scholarly Excellence in the Sciences subdivision. Each year, one award is given to junior faculty (between years 3 and 7) in each of the three subdivisions of CAS: Arts/Humanities, Social/Behavioral Sciences, and Sciences. The award requires off-campus peer references and includes a plaque and cash award. Congratulations Dr. Cabeen!

PhD candidate Chris Hamm brings a huge amount of microfluidics-based experimental work to fruition in a new publication about how different RsbR proteins influence the sigma-B response mediated by the stressosome in different stressors. He shows that RsbRA always shows a transient response, irrespective of stressor identity, but that other RsbR paralogs show different responses to different stressors. Hybrid fusion proteins show that both halves of RsbRA are required for its characteristic transient response. He was assisted in this work by undergraduate Dax Butler. Their work is in press at mBio as of November 2022. Congratulations, gentlemen!

Yes, E. coli and P. aeruginosa are both gamma-proteobacteria. But don't make the mistake of thinking that their metabolic preferences are the same. E. coli loves glucose, but P. aeruginosa would rather eat citrate-cycle intermediates like citrate and aconitate. Despite this preference, little has been known about the uptake mechanisms. New work by Dr. Simon Underhill revises the current model for citrate utilization by P. aeruginosa, showing the importance of the putative TctCBA transporter and identifying new and redundant citrate transporters. His work is in press at Journal of Bacteriology. 

Recent graduates Nina Baggett and Adam Bronson are co-first authors on new work examining the differences between the absence of the XerC recombinase and the loss of recombinase function (via mutation or drug treatments) with respect to the basis for pyocin overproduction. Their work shows that only deletion of, and not inactivation of, XerC induces non-canonical pyocin expression. Moreover, known peptide inhibitors of bacterial recombinases do not induce pyocin expression. Their work is published in Miicrobiology Spectrum.