Cookies and coffee will be available at 3:45pm…
THE PUZZLES OF FERRIC ENTEROBACTIN TRANSPORT THROUGH FepA
When Gram-negative bacteria acquire iron, the metal crosses both the outer membrane (OM) and the inner membrane (IM). But, existing radioisotopic uptake assays only measure iron passage into the cell as the accumulation of the radionuclide in the cytoplasm. We devised a novel methodology that exclusively observes the OM transport reaction of ferric enterobactin (FeEnt) by Escherichia coli FepA. This technique, called postuptake binding, revealed previously unknown aspects of TonB-dependent ferric siderophore transport reactions. The experiments showed, for the first time, that despite the discrepancy in cell envelope concentrations of FepA and TonB (approximately 35:1), all FepA proteins were active and equivalent in FeEnt uptake, with a maximum turnover number of approximately 5/min. The accumulation of FeEnt in the periplasm required the binding protein and inner membrane permease components of its overall transport system; postuptake binding assays on strains devoid of FepB, FepD, or FepG did not show uptake of FeEnt through the OM. However, fluorescence labeling data implied that FepA was active in the fepB-minus strain, suggesting that FeEnt entered the periplasm but then leaked out. Further experiments confirmed this futile cycle; cells without FepB transported FeEnt across the OM, but it immediately escaped through TolC. These ferric siderophore acquisition systems are crucial to the pathogenesis of Gram-negative bacteria, and our results show that cathecolate siderophores, which are transported by OM receptors such as FepA, CirA, FecA and Fiu, play a defining role in colonization of the gut by E.coli.
Anyone who falls asleep will hurt my feelings! 😉
Bewitching Kitchen 
Say what?!! ;-). Heehee…. puzzled over here for sure. Boy, I wish I could be there to nibble on cookies together and meet you in person… how fun would that be! Good luck with your presentation Sally :).
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Wouldn’t that be amazing? Hey, it only sounds complicated, it’s the lingo. The substance is a piece of cake. Did I say cake? I must be going nuts. Nuts? Well, this IS a food blog after all….
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Gosh, why didn’t I think of that. It should have been obvious to even the most casual of observers!
Good luck!
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I say that to myself on a daily basis…. 😉
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I will paint open eyes on my glasses. Hahahaha!
Best of luck to you, dear Sally.
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He, he, he… funny! Thanks, Adele!
Mission accomplished! Feels great!
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I have no plans at 3:45, but unfortunately it’s a bit long of a drive. 😉 Best of luck to you! Looks like it will be a very informative seminar. I should tell Mike to make cookies for his sometime. 🙂
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Thanks, Kristy… next time I’ll give more of an advanced notice!
I feel like a butterfly tonight, light and relieved!
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It’s been a long time since my bio classes on active and passive transport systems, I might need to have it ‘dumbed down’ just a little. But it would be fun to get together for a post seminar booze up at the student center/pub. 🙂 Too bad they won’t let me drive for a while longer so I’ll have to be there in spirit.
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Too bad you could not be here “for real”. INdeed, a lot has changed in the passive and active transport system over the years, but I am sure glad I work on the active transport side, as it’s a lot more exciting and complex (well, don’t tell anyone in the “other team” 😉
I will sleep very well tonight, good to have this over!
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Too far away – will you be podcasting? 🙂
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Oh, gosh Celia – definitely NOT…. the idea of recording my talk would very likely just paralyze me. Literally! 😉
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Dh and I find your work interesting-we’re both in the medical field.Sometime in the last year or so there was a report on gut flora in Scientific American. Researching cell mechanisms can lead to breakthroughs that can benefit disease control. My hat is off to you and Phil…
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Thank you! We both feel there’s so much to do, and not enough time, not enough hands, not enough resources. But, I would not change my work for anything… and I know Phil feels exactly the same way.
We are lucky to be able to do something we love for a living.
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Sally, I’d just there to look at your pretty smile 🙂 ah and the cookie too 🙂
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You are beyond nice! but I can see that the cookies would be intense competition for my talk… 😉
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I went to this last year. The cookies were store bought.
Pass.
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Yeah, right…. But OF COURSE they were store bought! You think I wuold bake the cookies and then give a talk? 🙂
(come to think of it, I just baked a cake and brought to the department yesterday… )
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I understood that one word, “gut”.. because my “gut” was asking when would the cookies be happening:D I’m so impressed by your brilliance, Sally!! Go get ’em with your lecture!! xx
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Wish I was as brilliant as you think! 😉 But I am a lot more stubborn and persistent than clever, and that often works well for research. You simply cannot give up and let the frustrations of puzzling results bring you down.
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I’ll take “BioChemisty” for 1000, Alex.
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he, he, he….
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I actually considered coming. So as not to add to your stress by having a guest to entertain I would have shown up just in time for the talk then helped you celebrate afterwards. Maybe next time.
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Oh, you crazy woman! You would have killed me right on the spot! 😉
I already almost got into hyperventilation when I saw the director of the Cancer Research Center entering the room. First time I saw him in the Biochem seminar series, my knees got a bit weak. He sat on the FIRST ROW, right in the center, can you imagine the pressure?
seriously, thanking for considering the loooong drive, but you must come when I am not at risk of a cardiac arrest 😉 December is sounding pretty good!
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I hope your siminar went really well Sally!
You reminded me of when I was preparing my thesis.. Trying to tell any one out of the field was a lost cause after the first 5 minutes. Maybe I should have baked them cookies
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