scholarly journals The structure of Escherichia coli BtuF and binding to its cognate ATP binding cassette transporter

2002 ◽  
Vol 99 (26) ◽  
pp. 16642-16647 ◽  
Author(s):  
E. L. Borths ◽  
K. P. Locher ◽  
A. T. Lee ◽  
D. C. Rees
Keyword(s):  
Escherichia Coli ◽  
Atp Binding ◽  
Atp Binding Cassette Transporter ◽  
Atp Binding Cassette

scholarly journals The MalF P2 Loop of the ATP-Binding Cassette Transporter MalFGK2 from Escherichia coli and Salmonella enterica Serovar Typhimurium Interacts with Maltose Binding Protein (MalE) throughout the Catalytic Cycle

2008 ◽  
Vol 191 (3) ◽  
pp. 754-761 ◽  
Author(s):  
Martin L. Daus ◽  
Mathias Grote ◽  
Erwin Schneider
Keyword(s):  
Escherichia Coli ◽  
Salmonella Enterica ◽  
Binding Protein ◽  
Maltose Binding Protein ◽  
Cross Linking ◽  
Atp Binding ◽  
Cross Link ◽  
Atp Binding Cassette Transporter ◽  
Serovar Typhimurium ◽  
Atp Binding Cassette

ABSTRACT We have investigated the interaction of the uncommonly large periplasmic P2 loop of the MalF subunit of the maltose ATP-binding cassette transporter (MalFGK2) from Escherichia coli and Salmonella enterica serovar Typhimurium with maltose binding protein (MalE) by site-specific chemical cross-linking in the assembled transport complex. We focused on possible distance changes between two pairs of residues of the P2 loop and MalE during the transport cycle. The distance between MalF(S205C) and MalE(T80C) (∼5 Å) remained unchanged under all conditions tested. Cross-linking did not affect the ATPase activity of the complex. The distance between MalF(T177C) and MalE(T31C) changed from ∼10 Å to ∼5 Å upon binding of ATP (or maltose, with a less pronounced result) and was reset to ∼10 Å after hydrolysis of one ATP. A cross-link (∼25 Å) between MalF(S205C) and MalE(T31C) was observed only when the transporter resided in a transition state-like conformation, as was the case after vanadate trapping or in a binding protein-independent mutant, both of which are characterized by tight binding of unliganded MalE to the transporter. Thus, we propose that the observed cross-link is indicative of catalytic intermediates of the transporter. Together, our results strengthen the notion that the MalF P2 loop plays an important role in intersubunit communication. In particular, this loop is involved in keeping MalE in close contact with the transporter. The data are discussed with respect to a crystal structure and current transport models.

scholarly journals Disruption of lolCDE, Encoding an ATP-Binding Cassette Transporter, Is Lethal for Escherichia coli and Prevents Release of Lipoproteins from the Inner Membrane

2002 ◽  
Vol 184 (5) ◽  
pp. 1417-1422 ◽  
Author(s):  
Shin-ichiro Narita ◽  
Kimie Tanaka ◽  
Shin-ichi Matsuyama ◽  
Hajime Tokuda
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Amino Acid Sequences ◽  
Atp Binding ◽  
Nonpermissive Temperature ◽  
Inner Membrane ◽  
E Coli ◽  
Atp Binding Cassette Transporter ◽  
Membrane Lipoproteins ◽  
Atp Binding Cassette

ABSTRACT ATP-binding cassette transporter LolCDE was previously identified, by using reconstituted proteoliposomes, as an apparatus catalyzing the release of outer membrane-specific lipoproteins from the inner membrane of Escherichia coli. Mutations resulting in defective LolD were previously shown to be lethal for E. coli. The amino acid sequences of LolC and LolE are similar to each other, but the necessity of both proteins for lipoprotein release has not been proved. Moreover, previous reconstitution experiments did not clarify whether or not LolCDE is the sole apparatus for lipoprotein release. To address these issues, a chromosomal lolC-lolD-lolE null mutant harboring a helper plasmid that carries the lolCDE genes and a temperature-sensitive replicon was constructed. The mutant failed to grow at a nonpermissive temperature because of the depletion of LolCDE. In addition to functional LolD, both LolC and LolE were required for growth. At a nonpermissive temperature, the outer membrane lipoproteins were mislocalized in the inner membrane since LolCDE depletion inhibited the release of lipoproteins from the inner membrane. Furthermore, both LolC and LolE were essential for the release of lipoproteins. On the other hand, LolCDE depletion did not affect the translocation of a lipoprotein precursor across the inner membrane and subsequent processing to the mature lipoprotein. From these results, we conclude that the LolCDE complex is an essential ABC transporter for E. coli and the sole apparatus mediating the release of outer membrane lipoproteins from the inner membrane.

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