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Solution structure of the oxidized iron-sulfur protein adrenodoxin from Encephalitozoon cuniculi. Seattle Structural Genomics Center for Infectious Disease target EncuA.00705.a
Structural highlights
FunctionADRX_ENCCU Ferredoxins are iron-sulfur proteins that transfer electrons in a wide variety of metabolic reactions. Publication Abstract from PubMedEncephalitozoon cuniculi is a unicellular, obligate intracellular eukaryotic parasite in the Microsporidia family and one of the agents responsible for microsporidosis infections in humans. Like most Microsporidia, the genome of E. cuniculi is markedly reduced and the organism contains mitochondria-like organelles called mitosomes instead of mitochondria. Here we report the solution NMR structure for a protein physically associated with mitosome-like organelles in E. cuniculi, the 128-residue, adrenodoxin-like protein Ec-Adx (UniProt ID Q8SV19) in the [2Fe-2S] ferredoxin superfamily. Oxidized Ec-Adx contains a mixed four-strand beta-sheet, beta2-beta1-beta4-beta3 ( downward arrow upward arrow upward arrow downward arrow), loosely encircled by three alpha-helices and two 310 -helices. This fold is similar to the structure observed in other adrenodoxin and adrenodoxin-like proteins except for the absence of a fifth anti-parallel beta-strand next to beta3 and the position of alpha3. Cross peaks are missing or cannot be unambiguously assigned for 20 amide resonances in the (1) H-(15) N HSQC spectrum of Ec-Adx. These missing residues are clustered primarily in two regions, G48-V61 and L94-L98, containing the four cysteine residues predicted to ligate the paramagnetic [2Fe-2S] cluster. Missing amide resonances in (1) H-(15) N HSQC spectra are detrimental to NMR-based solution structure calculations because (1) H-(1) H NOE restraints are absent (glass half-empty) and this may account for the absent beta-strand (beta5) and the position of alpha3 in oxidized Ec-Adx. On the other hand, the missing amide resonances unambiguously identify the presence, and immediate environment, of the paramagnetic [2Fe-2S] cluster in oxidized Ec-Adx (glass half-full). Solution structure for an Encephalitozoon cuniculi adrenodoxin-like protein in the oxidized state.,Shaheen S, Barrett KF, Subramanian S, Arnold SLM, Laureanti JA, Myler PJ, Van Voorhis WC, Buchko GW Protein Sci. 2020 Mar;29(3):809-817. doi: 10.1002/pro.3818. Epub 2020 Jan 20. PMID:31912584[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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