4Q4A

Improved model of AMP-PNP bound TM287/288

Summary for 4Q4A

• Entry DOI: 10.2210/pdb4q4a/pdb
• Related: 3QF4 4Q4H 4Q4J
• Descriptor: ABC transporter, Uncharacterized ABC transporter ATP-binding protein TM_0288, PHOSPHOAMINOPHOSPHONIC ACID-ADENYLATE ESTER, ... (4 entities in total)
• Functional Keywords: abc exporter, multidrug transport, abc transporter, membrane transporter, hydrolase-transport protein complex, hydrolase/transport protein
• Biological source: Thermotoga maritima; More
• Cellular location: Cell membrane ; Multi-pass membrane protein : Q9WYC4
• Total number of polymer chains: 2
• Total formula weight: 133381.17

Authors

Hohl, M.,Gruetter, M.G.,Seeger, M.A. (deposition date: 2014-04-14, release date: 2014-07-16, Last modification date: 2024-02-28)

Primary citation

Hohl, M.,Hurlimann, L.M.,Bohm, S.,Schoppe, J.,Grutter, M.G.,Bordignon, E.,Seeger, M.A.
Structural basis for allosteric cross-talk between the asymmetric nucleotide binding sites of a heterodimeric ABC exporter.
Proc.Natl.Acad.Sci.USA, 111:11025-11030, 2014

PubMed Abstract: ATP binding cassette (ABC) transporters mediate vital transport processes in every living cell. ATP hydrolysis, which fuels transport, displays positive cooperativity in numerous ABC transporters. In particular, heterodimeric ABC exporters exhibit pronounced allosteric coupling between a catalytically impaired degenerate site, where nucleotides bind tightly, and a consensus site, at which ATP is hydrolyzed in every transport cycle. Whereas the functional phenomenon of cooperativity is well described, its structural basis remains poorly understood. Here, we present the apo structure of the heterodimeric ABC exporter TM287/288 and compare it to the previously solved structure with adenosine 5'-(β,γ-imido)triphosphate (AMP-PNP) bound at the degenerate site. In contrast to other ABC exporter structures, the nucleotide binding domains (NBDs) of TM287/288 remain in molecular contact even in the absence of nucleotides, and the arrangement of the transmembrane domains (TMDs) is not influenced by AMP-PNP binding, a notion confirmed by double electron-electron resonance (DEER) measurements. Nucleotide binding at the degenerate site results in structural rearrangements, which are transmitted to the consensus site via two D-loops located at the NBD interface. These loops owe their name from a highly conserved aspartate and are directly connected to the catalytically important Walker B motif. The D-loop at the degenerate site ties the NBDs together even in the absence of nucleotides and substitution of its aspartate by alanine is well-tolerated. By contrast, the D-loop of the consensus site is flexible and the aspartate to alanine mutation and conformational restriction by cross-linking strongly reduces ATP hydrolysis and substrate transport.

PubMed: 25030449
DOI: 10.1073/pnas.1400485111

Experimental method

X-RAY DIFFRACTION (2.6 Å)