Protein Linkers Provide Limits on the Domain Interactions in the ABC Importer GlnPQ and Determine the Rate of Transport. Issue 8 (13th April 2018)

• Record Type: Journal Article
• Authors: Schuurman-Wolters, Gea K.; de Boer, Marijn; Pietrzyk, Martyna K.; Poolman, Bert
• Is Part Of: Journal of molecular biology. Volume 430:Issue 8(2018)
• Page Start: 1249
• Page End: 1262
• Publication Date: 2018-04-13
• Subjects: ABC transporter ATP-binding cassette transporter -- SBP substrate-binding protein -- SBD substrate-binding domain -- NBD nucleotide-binding domain -- TMD transmembrane domain; ABC transporter -- amino acid uptake -- inter-domain interactions -- multi-domain protein complexes -- transport efficiency; Molecular biology -- Periodicals; Biology -- Periodicals; Biochemistry -- Periodicals; Bacteriology -- Periodicals; Molecular Biology -- Periodicals; Biochemistry -- Periodicals; Biologie moléculaire -- Périodiques; Biologie -- Périodiques; Biochimie -- Périodiques; Moleculaire biologie; Biochemistry; Biology; Molecular biology; Periodicals; 572.805
• DOI: 10.1016/j.jmb.2018.02.014
• Languages: English
• ISSNs: 0022-2836

Abstract

Abstract: GlnPQ is an ATP-binding cassette importer with a unique domain organization and intricate transport behavior. The protein has two extracytoplamic substrate-binding domains (SBDs) per membrane subunit, each with different specificity for amino acids and different spacing to the translocator domain. We determined the effect of the length and structure of the linkers, which connect the SBDs to each other and to the membrane-embedded translocator domain, on the transport by GlnPQ. We reveal that varying the linker length impacts transport in a dual manner that depends on the conformational dynamics of the SBD. Varying the linker length not only changes the time for the SBD to find the translocator (docking) but also changes the probability to release the substrate again, thus altering the transport efficiency. On the basis of the experimental data and mathematical modeling, we calculate the docking efficiency as function of linker length and lifetime of the closed conformation. Importantly, not only linker length but also features in the sequence are important for efficient delivery of substrate from SBD to the translocator. We show that the linkers provide a platform for SBD docking and are not merely flexible structures. Graphical Abstract: Highlights: The ABC importer GlnPQ uses four substrate-binding domains to import amino acids. Interdomain linkers determine the efficiency of transport. Linker length affects time for SBD to find the translocator. Transport cycle is aborted when substrate is lost prior to docking of the receptor. Linker between SBD and TMD provides platform for SBD docking.