PCE3 seminar by Georgia Tech prebiotic chemists!


Please join us for another session of the PCE3 seminar series on June 24 at 1:00-2:30 pm (EST). This session we are excited to hear from Tyler Roche and Bryce Clifton, both graduate students at the Georgia Institute of Technology. We will also have a short topical introduction from Dr. Nicholas Hud, Professor at the Georgia Institute of Technology. We hope you can join us for another exciting session!

Tyler Roche will talk about “The Key to Prebiotic Nucleoside Formation?”

Bryce Clifton will talk about “Achieving multiple rounds of nucleic acid replication in a prebiotic solvent: A solution to the product inhibition problem”

Please use this link to register. In the event the zoom meeting reaches capacity the meeting will be live streamed to the PCE3 youtube channel.

Seminal Papers in Astrobiology Spring 2021 Schedule


Spring 2021 Seminal Papers in Astrobiology schedule is now finalized! Guests, we welcome you to sit in on the presentations and discussions. Because this is a course with participation points given for students taking it for a grade, guests are asked to please reserve questions/comments until the end of the discussion period. Course meetings are Wednesdays 9:30-11:25 am Eastern on Blue Jeans: https://gatech.bluejeans.com/891027890

M. Khademian – Virtual Seminar – May 8

ExplOrigins & Astrobiology Primer Community Review

Speaker: Maryam Khademian

Affiliation: University of Illinois, Department of Microbiology

Date: Friday, May 8, 2020 – 10:00am

Location: BlueJeans

Host: ExplOrigins Group

Title: Oxidative Stress in Anoxic Habitats

Abstract: Bacteroides thetaiotaomicron was examined to determine whether its obligate anaerobiosis is imposed by endogenous reactive oxygen species or by molecular oxygen itself. Previous analyses established that aerated B. thetaiotaomicron loses some enzyme activities due to a high rate of endogenous superoxide formation. However, the present study establishes that another key step in central metabolism is poisoned by molecular oxygen itself. Pyruvate dissimilation was shown to depend upon two enzymes, pyruvate:formate lyase (PFL) and pyruvate:ferredoxin oxidoreductase (PFOR), that lose activity upon aeration. PFL is a glycyl-radical enzyme whose vulnerability to oxygen is already understood. The rate of PFOR damage was unaffected by the level of superoxide or peroxide, showing that molecular oxygen itself is the culprit. The cell cannot repair PFOR, which amplifies the impact of damage. The rates of PFOR and fumarase inactivation are similar, suggesting that superoxide dismutase is calibrated so the oxygen- and superoxide-sensitive enzymes are equally sensitive to aeration. The physiological purpose of PFL and PFOR is to degrade pyruvate without disrupting the redox balance, and they do so using catalytic mechanisms that are intrinsically vulnerable to oxygen. In this way the anaerobic excellence and oxygen sensitivity of B. thetaiotaomicron are two sides of the same coin.