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Conformational Changes of a Type II ABC Importer for Small Substrate Transport
Author(s) -
Pinkett Heather
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.498.1
Subject(s) - atp binding cassette transporter , cytoplasm , chromosomal translocation , biophysics , chemistry , transport protein , electron paramagnetic resonance , transporter , electron paramagnetic resonance spectroscopy , biochemistry , microbiology and biotechnology , biology , gene , physics , nuclear magnetic resonance
ATP‐Binding Cassette (ABC) importers work as molecular pumps to transport substrates across the cellular membrane into the cytoplasm. To understand how the helices in the transmembrane domains (TMDs) of a transporter reposition themselves to allow a small compound to pass into the cell, our research has focused on ABC importers from Haemophilius influenzae as a model. Our studies of ABC importers revealed two transport systems within the same organism that transport the same substrate, molybdate. Using electron paramagnetic resonance spectroscopy (EPR) to capture a snapshot of the MolB 2 C 2 ‐A complex at each point in the transport mechanism, we identified four states, from apo to post‐ATP hydrolysis. The translocation pathway of MolBC opens just enough to allow through a small substrate, suggesting that in addition to the SBP, the size of the translocation pathway size provides an additional selectivity filter; thus, the transport mechanisms of ABC importers are more mechanistically diverse than previously thought. These results reveal that the mechanism of a Type II transporter for a small substrate may differ when compared to the mechanism transporters of large substrates.