Congratulations, Dr. Shannon Rivera!

Shannon Rivera

Shannon Rivera successfully defended her dissertation, “Elucidating the Various Roles of the Globin Domain from Globin Coupled Sensors”, on March 21st, 2019. Shannon’s committee was led by Emily Weinert with Brian Dyer and Stefan Lutz as additional members.

During her time at Emory, Shannon was supported by an Emory Graduate Diversity Fellowship as well as a Carl Storm Underrepresented Minority (CSURM) Fellowship. She was also recognized with the department’s Outstanding T.A. Award for Analytical Chemistry in 2014 and the Quayle Outstanding Student Award in 2018.

Shannon has also been involved in several student organizations including Pi Alpha Chemical Society (PACS) where she served for one year as Vice President of Community Service and the Association for Women in Science (AWIS) where she served consecutive terms first as Co-Social Chair and then as Communications Chair. She has also been a long time member of the Chemistry Graduate School Prep Club sponsored by the NSF Center for Selective C-H Functionalization, serving as President in 2017 and 2018. CGSPC connects Atlanta-area undergraduates from PUIs and HBCUs (including Agnes Scott, Spelman, Morehouse, and Clarke-Atlanta) with mentors who help them to connect with mentors who can help them navigate the graduate school application process . Shannon was instrumental in bringing CGSPC students to Emory for an on-site mentoring event. “They got to talk to faculty, grads, and post-docs about admissions and the struggles of being under represented in the sciences. The effect the event had of them and the fact that it cemented the drive to go to graduate school for those students, that is what made it a huge accomplishment for me,” says Shannon.

Scientifically, Shannon’s work was recently recognized with an invitation to give two oral presentations at SERMACS and GRS/GRC Metals in Biology. SERMACS receives well over 1,000 applications for oral applications and awards only 12-15 spots. “Scientifically though, the most fun and impactful accomplishment was successfully crystallizing my protein, BpeGlobin,” says Shannon. “It was fun because my protein is red, so my crystals are red! They came in different shapes, but you could always see them.  It is also very important for my scientific community because its the first crystal of  the signaling domain of a Globin-coupled sensor with oxygen in the pocket; the gas responsible for activating the protein.”

Shannon plans to pursue a career in industry.

Congratulations, Shannon!

Congratulations, Dr. Yao Jing!

On Wednesday, March 28th, Yao Jing successfully defended her thesis, “Structure-Activity Relationship and Quantitative Structure-Activity Relationship of GluN2C/D Subunit Selective Antagonists of the N-Methyl-D-Aspartate Receptor”. Yao’s thesis committee included her thesis advisor, Dr. Dennis Liotta, and members  Dr. Frank McDonald, Dr. Stephen Traynelis, and Dr. Emily Weinert.

Yao is currently searching for a job with an eye toward healthcare data science.

Congratulations, Dr. Jing!

First Person: Discovering the WaterHub at Emory

Analytical chemistry students listen to a tour guide at the WaterHub at Emory.
Analytical chemistry students listen to a tour guide in the front hall of the WaterHub at Emory.

By: Laura Briggs (EC ’19)

I didn’t know that the WaterHub existed until this semester, which is a shame because it’s right in my backyard. From my dorm room at 15 Eagle Row, I can see the greenhouse and the mysterious metal trapdoors embedded in the grassy area near Peavine Creek Drive. But it wasn’t until my analytical chemistry lab trekked across campus, collection bottles and safety goggles in hand, that I learned how awesome the WaterHub really is.

One of the first things you see when you enter the WaterHub is a banana tree, happily flourishing among the greenery in the heat and humidity. Besides providing me with a bit of joy, the tree is working full-time for a greater cause. Its roots are the centerpiece of a hydroponic reactor beneath the greenhouse that harnesses the natural design of plants to provide efficient and stable water treatment.

As our tour guide explained to the class, the WaterHub recycles up to 400,000 gallons of water every day, meeting almost 40% of Emory’s total water needs. Don’t worry, though- our guide reassured us that repurposed sewage is not coming out of the water fountains. Instead, the recycled water heats and cools buildings and helps flush toilets in some of Emory’s dorms.

How does this Cinderella transformation occur? The treatment process begins with a series of moving bed bioreactors to settle out and digest the – um – solid components of sewage. These large tanks contain a floating plastic netting system where bacteria can settle and grow into compact communities called biofilms.

Different kinds of bacteria proliferate in different bioreactors, and the WaterHub puts each of them to work cleaning various components of the wastewater. Oxygen levels control the types of bacteria that flourish. One bioreactor is completely anaerobic, encouraging the growth of bacteria that can “denitrify” the water, reducing dangerous nitrates into harmless nitrogen gas. Other bioreactors have different oxygen conditions, and the microbes that grow there perform other functions.

The next step in the process also relies on nature; a vast network of plant roots dips down into a series of hydroponic reactors, providing maximum surface area for more junk-eating microbes to inhabit. Alongside the plants, there’s also an artificial system of textile webbing to provide additional filtration.

At this point in the treatment system, the water is pretty clear, and almost all contaminants have been removed. Still, the process isn’t over. Water passes through a clarifier and a filter, removing any remaining solids, nutrients, and color from the water. Finally, any straggling biological contaminants are zapped away with a combination of chlorine and ultraviolet (UV) light. Our class sampled this fully-repurposed water to test for various contents (Here is my blog post exploring this process in-depth!)

The WaterHub – once a mystery to me – is a brilliant marriage of sustainability, engineering, chemistry, and biology right on Peavine Creek Drive! Thanks to Dr. Weaver’s analytical chemistry lab course, I can now look out my dorm room window and appreciate the source of the water that heats the building on these cold winter nights – and the beautifully-evolved natural processes that keep it clean.

orange line

Laura BriggsLaura Briggs is a sophomore majoring in chemistry and dance. Laura is a Woodruff Scholar and the Vice President of the Emory Swing Dance Club. She is also a member of the Emory Dance Company and hosts a weekly, science-themed radio show. Laura is a research assistant in the Weinert lab, where she studies really cool bacteria that attack potatoes. Laura plans to pursue either a Ph.D. in biochemistry or a master’s in science writing.

To learn more about the WaterHub, check out this link from Campus Services!

Weinert Group in Nature Communications

Clip from the image RsbR haem pocket model and haem spectra." This image, and the article referenced, are licensed under a Creative Commons Attribution 4.0 International License.
Clip from the image RsbR haem pocket model and haem spectra.” This image, and the article referenced, are licensed under a Creative Commons Attribution 4.0 International License.

The Weinert Group has research featured in the June issue of Nature Communications. The paper, “An O2-sensing stressosome from a Gram-negative bacterium,” is co-authored by Xin Jia, Jian-bo Wang, Shannon Rivera, Duc Duong, and Emily E. Weinert.


Bacteria have evolved numerous pathways to sense and respond to changing environmental conditions, including, within Gram-positive bacteria, the stressosome complex that regulates transcription of general stress response genes. However, the signalling molecules recognized by Gram-positive stressosomes have yet to be identified, hindering our understanding of the signal transduction mechanism within the complex. Furthermore, an analogous pathway has yet to be described in Gram-negative bacteria. Here we characterize a putative stressosome from the Gram-negative bacterium Vibrio brasiliensis. The sensor protein RsbR binds haem and exhibits ligand-dependent control of the stressosome complex activity. Oxygen binding to the haem decreases activity, while ferrous RsbR results in increased activity, suggesting that the V. brasiliensis stressosome may be activated when the bacterium enters anaerobic growth conditions. The findings provide a model system for investigating ligand-dependent signalling within stressosome complexes, as well as insights into potential pathways controlled by oxygen-dependent signalling within Vibrio species.

[Full Article]

Chemistry and the Atlanta Science Festival

Undergraduate Chris Hernandez. Photo by Emory Photo/Video.
Undergraduate Chris Hernandez. Photo by Emory Photo/Video.

ChEmory, Emory’s undergraduate ACS club, presented demos at the 2014 Atlanta Science Festival. The demos were the featured entertainment during intermission of the “Science at Emory: The Lab Changing the World” even. At the same event, Susanna Widicus Weaver gave a public talk titled “Chemical Complexity in the Universe” to an audience of over 200. Over 40 audience members visited the department for lab tours following the event. Thanks to event organizers Ilya Nemenman (Physics), David Lynn, Simon Blakey, and graduate student Darcie Cook.

ChEmory demos were again featured at the Exploration Expo held downtown at the Georgia World Congress Center on the last day of the festival. Chemistry undergraduate Chris Hernandez was featured in an Emory Report article about the demos. Jeremy Weaver was featured in a WSB-TV video advertising the festival.

Emory Department of Chemistry graduate student Brandon Greene organized the popular “Science of Beer” event during the Atlanta Science Festival. The event sold out within a day of tickets being made available online, although Pi Alpha Chemical Society made additional tickets available to our graduate students at no charge. The event featured talks about the chemistry of beer and yeast by speakers including Prof. Emily WeinertMonday Night Brewing Company provided three special beers for attendees that helped to illustrate the concepts described in the talks.

Faculty Spotlight: Emily Weinert

Q: What made you decide to major in chemistry?

EW: My dad’s a physicist. I grew up spending time thinking about `here’s the natural world, what’s going on’ kind of questions-so I love science. And I just really like the molecular level understanding, trying to really understand. In college, I loved organic chemistry because once you understand what’s happening, it can be predictive. I love being able to do the experiments, have a prediction, go in test it and ask “Does that make sense?”.

Q: What made you transition to biomolecular chemistry?

EW: I’ve always really been interested in living systems and trying to sort out what’s happening in these complex systems. I had always hoped to get to the part in my Ph.D. (working with quinone methides) where we’d learned enough to go in vivo and test some of our theories. But like so often happens in science, sometimes you find that you really don’t understand things that well or you get drawn in different paths-so I wanted to do something more biological after focusing on small molecules.

Q: Did you ever want to be anything else?

EW: Actually, when I was growing up I wanted to be a wildlife biologist.

Q: Really?

EW: Yeah, live out in the wild and count the wolves and watch their migration patterns… But then I realized I didn’t really like the cold that much and living out in a tent with things that could eat me makes me a little nervous so I ran for the lab instead. I think it worked out a lot better.

Q: And you have, like, you know…plumbing

EW: Yeah, (laughs) that was another thing.

Q: What research does your lab focus on?

EW: My lab does protein chemistry. We’re interested in understanding how proteins work, thinking about them as complex chemical systems rather than as the normal circles and pac-men that we often see.

The two general interests in the lab are heme proteins and nucleotide signaling. We have some proteins that are heme proteins and some proteins that are involved in nucleotide signaling and at the intersection are a group of proteins that have both heme domains and do nucleotide chemistry. We’re looking at cyclic nucleotide signaling in bacteria and some potentially new cyclic nucleotides that are involved in pathways in mammals.

We’re also interested in heme proteins and how protein scaffolds tune the electronics and the reactivity of the heme itself. A lot of heme proteins use protoporphyrin IX, although there are some other porphyrins, but you can take protoporphyrin IX and do chemistry with oxygen, like peroxidases and P450 enzymes. And you can also use the same porphyrin to do reversible ligand binding for oxygen delivery or for sensing. So organisms can actually sense gases, binding very low concentrations of ligand so that it causes a downstream change in the organism.

Q: And this variation in activity is dependent on the protein structure?

EW: Yes, the scaffold itself. So you can change the redox potential widely from around -400 mV to around 380 mV. That’s a huge change. You can change the type of reaction; you can change if you can do electron transfer with most of the biologically available oxidants and reductants. And so it can changes just about everything. And right now, our understanding of that is still pretty poor. There’s a huge amount of work that’s been done on the globins. I think there are probably at least 150 mutants of myoglobin that have been published, but it’s still not very predictive and we can’t always apply it to other heme proteins. So, like most protein engineering or protein chemistry, we don’t have a lot of predictive power to suggest how mutations will affect the heme.

Q: Which chemist do you wish you had an opportunity to meet?

EW: Rosalind Franklin and Hans Fischer.

Q: Why them?

Rosalind Franklin has a fascinating story. The work she was doing was still in a time when it was not necessarily expected that many women did their own science. She was clearly brilliant and she figured out most of the structure of DNA before Watson and Crick. The reason Watson and Crick got the structure was by looking at her data. Unfortunately she died before the Nobel Prize was given and they don’t give it posthumously. I think she would be fascinating to talk to and to hear her story.

Hans Fischer was the first to discover chlorophyll and heme and he was the first one to figure out what these pigments were and to synthesize them. I think it’s really interesting to think of how do you go about, at the time (the 1920’s), saying `I’m going to isolate this colored compound’ and then how do you go about with the techniques then available figuring out what all is in there? I think it would be really interesting to hear how the field got started from the guy that started the field!