title: SecA, the motor of the secretion machine, binds diverse partners on one interactive surface.
abstract: In all living cells, regulated passage across membranes of specific proteins occurs through a universally conserved secretory channel. In bacteria and chloroplasts, the energy for the mechanical work of moving polypeptides through that channel is provided by SecA, a regulated ATPase. Here, we use site-directed spin labeling and electron paramagnetic resonance spectroscopy to identify the interactive surface used by SecA for each of the diverse binding partners encountered during the dynamic cycle of export. Although the binding sites overlap, resolution at the level of aminoacyl side chains allows us to identify contacts that are unique to each partner. Patterns of constraint and mobilization of residues on that interactive surface suggest a conformational change that may underlie the coupling of ATP hydrolysis to precursor translocation.
authors.affiliation: Department of Biochemistry, 117 Schweitzer Hall, University of Missouri, Columbia, MO 65211, USA.
authors.forename: Dylan B
authors.initials: DB
authors.lastname: Cooper
authors.forename: Virginia F
authors.initials: VF
authors.lastname: Smith
authors.forename: Jennine M
authors.initials: JM
authors.lastname: Crane
authors.forename: Hilary C
authors.initials: HC
authors.lastname: Roth
authors.forename: Angela A
authors.initials: AA
authors.lastname: Lilly
authors.forename: Linda L
authors.initials: LL
authors.lastname: Randall
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D004926:Escherichia coli / Q000378:metabolism*; D008024:Ligands; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D020409:Molecular Motor Proteins / Q000737:chemistry / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017510:Protein Folding; D017433:Protein Structure, Secondary; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D013113:Spin Labels; D013499:Surface Properties
chemical_list: D001426:Bacterial Proteins; D008024:Ligands; D026901:Membrane Transport Proteins; D020409:Molecular Motor Proteins; D010455:Peptides; D000069816:SEC Translocation Channels; D013113:Spin Labels; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins