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pnas.orgCharacterization and engineering of a plastic-degrading aromatic polyesteraseSynthetic polymers are ubiquitous in the modern world but pose a global environmental problem. While plastics such as poly(ethylene terephthalate) (PET) are highly versatile, their resistance to natural degradation presents a serious, growing risk to fauna and flora, particularly in marine environments. Here, we have characterized the 3D structure of a newly discovered enzyme that can digest highly crystalline PET, the primary material used in the manufacture of single-use plastic beverage bottles, in some clothing, and in carpets. We engineer this enzyme for improved PET degradation capacity and further demonstrate that it can also degrade an important PET replacement, polyethylene-2,5-furandicarboxylate, providing new opportunities for biobased plastics recycling. Poly(ethylene terephthalate) (PET) is one of the most abundantly produced synthetic polymers and is accumulating in the environment at a staggering rate as discarded packaging and textiles. The properties that make PET so useful also endow it with an alarming resistance to biodegradation, likely lasting centuries in the environment. Our collective reliance on PET and other plastics means that this buildup will continue unless solutions are found. Recently, a newly discovered bacterium, Ideonella sakaiensis 201-F6, was shown to exhibit the rare ability to grow on PET as a major carbon and energy source. Central to its PET biodegradation capability is a secreted PETase (PET-digesting enzyme). Here, we present a 0.92 Å resolution X-ray crystal structure of PETase, which reveals features common to both cutinases and lipases. PETase retains the ancestral α/β-hydrolase fold but exhibits a more open active-site cleft than homologous cutinases. By narrowing the binding cleft via mutation of two active-site residues to conserved amino acids in cutinases, we surprisingly observe improved PET degradation, suggesting that PETase is not fully optimized for crystalline PET degradation, despite presumably evolving in a PET-rich environment. Additionally, we show that PETase degrades another semiaromatic polyester, polyethylene-2,5-furandicarboxylate (PEF), which is an emerging, bioderived PET replacement with improved barrier properties. In contrast, PETase does not degrade aliphatic polyesters, suggesting that it is generally an aromatic polyesterase. These findings suggest that additional protein engineering to increase PETase performance is realistic and highlight the need for further developments of structure/activity relationships for biodegradation of synthetic polyesters.
aluxurytravelblog.comExploring the Bahamas: family style - A Luxury Travel BlogWhen you hear the word “Bahamas” what comes to mind? White sandy beaches. Water so clear you can see your toes as exotic colored fish and other marine life weave in and out of your legs. Palm trees, warm breezes, and cold beverages topped with umbrellas. These picturesque descriptions are synonymous with the Bahamas, and …2
thetakeout.comWhat perfectly normal food can you just not stand?We’ve noticed here at The Takeout that practically everyone has their own weird food peculiarities. Staffer Gwen Ihnat’s husband won’t eat fruit, for example. Editor Kevin Pang can’t stand the sight of cottage cheese. We’ve had friends who can’t do hot beverages or hate the texture of melted cheese. And we know someone who just straight-up hates pizza. Pizza!
lifehacker.comBuy Yourself an Electric Mug Warmer When you’re drinking a hot beverage, you want that beverage to remain hot. Of course you do! You’re a human being with needs. Sadly, it won’t—you can’t fight the second law of thermodynamics; even if you prime your cup first, eventually entropy will have its way. Eventually, you’ll take a swig of your coffee or your tea and get a mouthful of lukewarm disappointment. If your 9am cup tastes like a brand new day, full of promise, then your 10:15 dregs remind you that it’s seven hours until you can start drinking.