1 H, 13 C, 15 N backbone resonance assignments of the apo and holo forms of the ABC transporter solute binding protein P
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ARTICLE
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H, 13C, 15N backbone resonance assignments of the apo and holo forms of the ABC transporter solute binding protein PiuA from Streptococcus pneumoniae Katherine A. Edmonds1 · Yifan Zhang1,2,3 · Daniel J. Raines4 · Anne‑K. Duhme‑Klair4 · David P. Giedroc1,3 Received: 28 March 2020 / Accepted: 29 May 2020 © Springer Nature B.V. 2020
Abstract Streptococcus pneumoniae is a Gram-positive human pathogen that causes millions of infections worldwide with an increasing occurrence of antibiotic resistance. Iron acquisition is essential for its survival and virulence, especially under hostimposed nutritional immunity. S. pneumoniae expresses several ATP-binding cassette (ABC) transporters to facilitate acquisition under iron limitation, including PitABCD, PiaABCD, and PiuBCDA. The substrate specificity of PiuBCDA is not fully established. Herein, we report the backbone 1H, 13C and 15N resonance assignments of the 31 kDa soluble, extracellular domain of the substrate binding protein PiuA in the apo form and in complex with Ga(III) and the catechol siderophoremimic 4-LICAM. These studies provide valuable information for further functional studies of interactions with other proteins, metals, and small molecules. Keywords Iron acquisition · ABC transporter · Pathogen · Catechol · Siderophore · Streptococcus pneumoniae
Biological context Streptococcus pneumoniae is an important Gram-positive human pathogen (Lanie et al. 2007; Lynch and Zhanel 2010). Iron (Fe) is essential for its survival and pathogenicity, as it is essential for most living organisms, due to its ability to perform redox reactions and function as a cofactor for many proteins (Andreini et al. 2018). During infection, the host often limits the availability of iron in a process known as nutritional immunity (Hood and Skaar 2012). To respond to iron limitation, various S. pneumoniae strains express three different ABC transporters. PitABCD, PiaABCD, and PiuBCDA each facilitate iron uptake from different sources * David P. Giedroc [email protected] 1
Department of Chemistry, Indiana University, Bloomington, Indiana, USA
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Graduate Program in Biochemistry, Indiana University, Bloomington, Indiana, USA
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Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana, USA
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Department of Chemistry, University of York, Heslington, York YO10 5DD, UK
and as different Fe(III)-chelate complexes. Transporters such as these commonly recognize iron bound to heme or other small organic molecules, including various classes of siderophores (Zhang et al. 2020). S. pneumoniae is not known to endogenously biosynthesize siderophores and thus must rely on Fe piracy to meet nutritional Fe demands (Cheng et al. 2013). Hence, the regulated uptake of siderophore- or other small molecule-Fe(III) complexes produced by other, often competing, bacteria in polymicrobial communities or by the host is foundational to Fe piracy in S. pneumoniae. PiuA is the solute-binding protein (SBP) of the PiuABC transporter. As an extracellu
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