The structure of nontypeable Haemophilus influenzae SapA in a closed conformation reveals a constricted ligand-binding cavity and a novel RNA binding motif.

Autor: Lukacik P; Diamond Light Source, Harwell Science & Innovation Campus, Didcot, Oxfordshire, United Kingdom.; Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, Oxfordshire, United Kingdom., Owen CD; Diamond Light Source, Harwell Science & Innovation Campus, Didcot, Oxfordshire, United Kingdom.; Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, Oxfordshire, United Kingdom., Harris G; Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, Oxfordshire, United Kingdom., Bolla JR; Department of Chemistry, University of Oxford, Oxford, United Kingdom., Picaud S; Structural Genomics Consortium, University of Oxford, Oxford, United Kingdom., Alibay I; Department of Biochemistry, University of Oxford, Oxford, United Kingdom., Nettleship JE; Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, Oxfordshire, United Kingdom.; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom., Bird LE; Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, Oxfordshire, United Kingdom.; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom., Owens RJ; Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, Oxfordshire, United Kingdom.; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom., Biggin PC; Department of Biochemistry, University of Oxford, Oxford, United Kingdom., Filippakopoulos P; Structural Genomics Consortium, University of Oxford, Oxford, United Kingdom., Robinson CV; Department of Chemistry, University of Oxford, Oxford, United Kingdom., Walsh MA; Diamond Light Source, Harwell Science & Innovation Campus, Didcot, Oxfordshire, United Kingdom.; Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, Oxfordshire, United Kingdom.
Jazyk: angličtina
Zdroj: PloS one [PLoS One] 2021 Oct 15; Vol. 16 (10), pp. e0256070. Date of Electronic Publication: 2021 Oct 15 (Print Publication: 2021).
DOI: 10.1371/journal.pone.0256070
Abstrakt: Nontypeable Haemophilus influenzae (NTHi) is a significant pathogen in respiratory disease and otitis media. Important for NTHi survival, colonization and persistence in vivo is the Sap (sensitivity to antimicrobial peptides) ABC transporter system. Current models propose a direct role for Sap in heme and antimicrobial peptide (AMP) transport. Here, the crystal structure of SapA, the periplasmic component of Sap, in a closed, ligand bound conformation, is presented. Phylogenetic and cavity volume analysis predicts that the small, hydrophobic SapA central ligand binding cavity is most likely occupied by a hydrophobic di- or tri- peptide. The cavity is of insufficient volume to accommodate heme or folded AMPs. Crystal structures of SapA have identified surface interactions with heme and dsRNA. Heme binds SapA weakly (Kd 282 μM) through a surface exposed histidine, while the dsRNA is coordinated via residues which constitute part of a conserved motif (estimated Kd 4.4 μM). The RNA affinity falls within the range observed for characterized RNA/protein complexes. Overall, we describe in molecular-detail the interactions of SapA with heme and dsRNA and propose a role for SapA in the transport of di- or tri-peptides.
Competing Interests: NO authors have competing interests.
Databáze: MEDLINE
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