by Ananya Sen
The "Phage Meetings" have a long tradition. The first one was organized by Max Delbrück and held at Cold Spring Harbor in 1950. The meetings slowly evolved to include more and more molecular genetics of bacteria and nowadays, known as the "Molecular Genetics of Bacteria and Phages" meetings, they are held yearly in August at the University of Wisconsin, Madison. Prior to attending this year's meeting, I had only been to two small conferences, the Gordon Conference on Microbial Stress Responses and the Wind River Conference on Prokaryotic Biology. By comparison, the Madison meeting seemed huge with over 300 participants, 69 talks, and a staggering 237 poster presentations. The overview of the conference can be found here. Given the proximity of Madison to University of Illinois (where I am a graduate student) my advisor Jim Imlay encouraged our entire lab to attend. We jumped at the opportunity enticed by the prospects of great science and the thoughts of enjoying ice cream at the shore of Lake Mendota.
Despite being exhausted and a bit overwhelmed on the first day, I thoroughly enjoyed the opening keynote lecture by Eduardo Groisman. The talk covered his lab's journey from pathogenesis to physiology in Salmonella enterica serovar Typhimurium. He described how the PhoPQ two-component regulatory system responds to Mg2+ levels and cytoplasmic pH. The talk proved captivating as he traced the phenomenon to changes in ATP levels, which in turn decreased the growth rate and protein stability in the cell. Following his talk, the first session of the conference was equally intriguing. We learned about the various regulatory networks in such diverse species as Campylobacter jejuni, Caulobacter crescentus, Enterococcus faecalis, Vibrio cholerae, and Pseudomonas aeruginosa.
Personally, the most exciting part of a conference is meeting the authors of the papers I have read and studied. To be able to sit down with them over a meal, talk about science, lab life, and all their experiences is what makes conferences so enjoyable. Although my department is quite diverse, it is always interesting to meet my peers from other universities and swap stories about graduate life. It's also nice to meet familiar faces from previous conferences and see how wonderfully their science is progressing.
I would happily summarize all of the talks, but for the sake of brevity I include just a few. My apologies to the rest of the speakers. Shelley Copley chaired the metabolism session and gave a fascinating talk about novel metabolic pathways that E. coli can adapt when faced with the loss of the essential cofactor pyridoxal phosphate (PLP). E. coli deals with this unusual situation either by adopting serendipitous pathways that ultimately synthesize PLP or by using promiscuous enzymes that can substitute for enzymes in the PLP pathway. In the same session, we also heard from Maryam Khademian about how E. coli can use hydrogen peroxide as a terminal electron acceptor during anaerobic respiration. It sounds crazy that E. coli would adopt a poisonous molecule to carry out metabolism. However, we must also remember that organisms adapted to a similar "poisonous" molecule, oxygen, to develop aerobic metabolism which is vastly more energy efficient compared to anaerobic pathways.
Other session themes included bacterial development, cell division and shape determination, DNA repair and replication, transcription, and translation. We were updated on the latest advances in the antagonism between bacteria and phages through CRISPR and anti-CRISPR systems. Melanie Blokesch summarized the latest on the regulatory networks responsible for competence in Vibrio cholerae and how a type VI secretion system (T6SS) is an important part of the competence regulon. This system facilitates horizontal gene transfer by killing neighboring bacteria, followed by the absorption of their DNA. Absolutely fascinating! There were also talks that discussed bacterial cooperation, including one by Michi Taga on the sharing of corrinoid cofactors among members of complex bacterial communities. Although these cofactors are used by 80% of the bacteria, only 40% of them produce them. Furthermore, species show specificity in corrinoid utilization because different microbes produce structurally different ones.
A special mention must be made about the recipients of the Nat L. Sternberg Thesis Prize. This year they were Gregory Goldberg from The Rockefeller University and April Pawluk from University of Toronto. Goldberg's work focused on the interplay between the type III CRISPR-Cas systems in Staphylococcus aureus and infecting temperate phages. Surprisingly, these systems tolerate temperate phages during lysogenization, but not during lytic cycles. Pawluk used bioinformatic techniques to discover novel anti-CRISPR protein families that are present in mobile genetic elements in Proteobacteria. Furthermore, she showed that these protein families have evolved independently to inhibit the CRISPR-Cas functions in discrete ways.
There were three poster sessions given the large number of presenters. After the intense oral sessions, these were a welcome break, where one could interact with peers, seek out potential collaborators, and learn about future publications. A unique feature of this meeting was the dance party on the final night, which involved academics of all ages grooving on the dance floor. After all, following a total immersion into science for a week, everyone needed to release some steam before returning to their routine.
Ananya is a graduate student in the Department of Microbiology at the University of Illinois at Urbana-Champaign. She works in the lab of James A. Imlay. Ananya has recently started a blog of her own called "History Meets Science."