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- Rabe, Patrick, et al.
(författare)
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X-ray free-electron laser studies reveal correlated motion during isopenicillin N synthase catalysis
- 2021
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 7:34
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Tidskriftsartikel (refereegranskat)abstract
- Isopenicillin N synthase (IPNS) catalyzes the unique reaction of L-delta-(alpha-aminoadipoyl)-L-cysteinyl-D-valine (ACV) with dioxygen giving isopenicillin N (IPN), the precursor of all natural penicillins and cephalosporins. X-ray free-electron laser studies including time-resolved crystallography and emission spectroscopy reveal how reaction of IPNS:Fe(II):ACV with dioxygen to yield an Fe(III) superoxide causes differences in active site volume and unexpected conformational changes that propagate to structurally remote regions. Combined with solution studies, the results reveal the importance of protein dynamics in regulating intermediate conformations during conversion of ACV to IPN. The results have implications for catalysis by multiple IPNS-related oxygenases, including those involved in the human hypoxic response, and highlight the power of serial femtosecond crystallography to provide insight into long-range enzyme dynamics during reactions presently impossible for nonprotein catalysts.
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2. |
- Winkelmann, Iven, et al.
(författare)
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Structure and elevator mechanism of the mammalian sodium/proton exchanger NHE9
- 2020
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Ingår i: EMBO Journal. - : EMBO. - 0261-4189 .- 1460-2075. ; 39:24
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Tidskriftsartikel (refereegranskat)abstract
- Na+/H+ exchangers (NHEs) are ancient membrane-bound nanoma- chines that work to regulate intracellular pH, sodium levels and cell volume. NHE activities contribute to the control of the cell cycle, cell proliferation, cell migration and vesicle trafficking. NHE dysfunction has been linked to many diseases, and they are targets of pharma- ceutical drugs. Despite their fundamental importance to cell home- ostasis and human physiology, structural information for the mammalian NHEs was lacking. Here, we report the cryogenic elec- tron microscopy structure of NHE isoform 9 (SLC9A9) from Equus caballus at 3.2 Å resolution, an endosomal isoform highly expressed in the brain and associated with autism spectrum (ASD) and atten- tion deficit hyperactivity (ADHD) disorders. Despite low sequence identity, the NHE9 architecture and ion-binding site are remarkably most similar to distantly related bacterial Na+/H+ antiporters with 13 transmembrane segments. Collectively, we reveal the conserved architecture of the NHE ion-binding site, their elevator-like structural transitions, the functional implications of autism disease mutations and the role of phosphoinositide lipids to promote homodimerization that, together, have important physiological ramifications.
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