The intracellular signalling molecule or second messenger c-di-GMP promotes biofilm formation in most bacteria. In Escherichia coli, this involves inhibition of motility and stimulation of the synthesis of extracellular matrix components (amyloid ‘curli’ fibers and phosphoethanolamin (pEtN)-modified cellulose). Most commensal or pathogenic strains of E. coli have 12 enzymes (diguanylate cyclases or DGCs) that produce c-di-GMP, with this activity residing in their conserved GGDEF domains. By contrast, enteroaggregative Escherichia coli (EAEC) – a pathogen that adheres in biofilms to the human intestinal epithelium and cause chronic diarrhea – has yet another one of these enzymes, which is called DgcX. SPP1879 PI Regine Hengge and her team (Humboldt University Berlin) have discovered this extra DGC and are currently studying its function and regulation in EAEC. DgcX is expressed at very high levels and its N-terminal membrane-inserted domain has several highly conserved patches of amino acids on the outer side of the membrane that look like binding sites for some still unknown signal molecule that could activate c-di-GMP production by DgcX. Besides regulating standard biofilm functions, c-di-GMP generated by DgcX is likely to also control EAEC-specific virulence factors that have yet to be identified.
Signaling input and regulatory output of DgcX protein, which consists of an N-terminal domain with eight transmembrane segments followed by the globular GGDEF domain where c-di-GMP synthesis occurs.
Povolotsky and Hengge (2015) J. Bacteriol. 198: 111-126. PMID: 26303830
Richter et al. (2014) EMBO Mol. Med. 6: 1622-1637
@regine.hengge#spp1879#secondmessenger#signaltransduction#microbiology#bacteriology#bacteria#microbes#molecularbiology#biochemistry#cellbiology#lifescience#instascience#dailyscience#sciencelover#scienceiscool#scienceisawesome#laboratorylife#scicomm#deutscheforschungsgemeinschaft#humboldtuniversit ät #medicalmicrobiology#ecoli#escherichiacoli#biofilm ...
Something happened to that gummy bear on the left....
Can you explain it? #scienceiscool ...
I haven’t had a lot of time for crafts lately, however, I have found some time to work on this puzzle! I love Disney, and one of the magical things is the fireworks they set off every evening! I’m always in awe as colours fill the sky, though the chemist in me can’t help but come out during the displays of different colours... just ask my family. Last time I saw fireworks, I made a comment about how one was so bright, it must have contained the element magnesium.
Fireworks get their colours from the different chemicals that are packed with gunpowder. Different molecules produce different colours because of the arrangement and energy of electrons within the atoms. Electrons exist in different “energy levels”, that have very specific allowed energies. Think of these levels kind of like a set of stairs... you can step on the stair itself, but can’t step between steps. Electrons are the same.
They absorb energy to move up a step, and give off energy to go down a step.
The energy that electrons give off when moving down a step is in the form of light. Depending on how big or small the step is between energy levels, these electrons will give off different colours of light. The compounds put into fireworks are specifically chosen to have energy level gaps that correspond to the desired colour. To make the red fireworks, like in my puzzle, the fireworks likely contain compounds with strontium in them, such as strontium nitrate or strontium carbonate.