We present a quantitative analysis of conformational changes of the nucleotide-binding subunits, MalK(2), of the maltose ATP-binding cassette importer MalFGK(2) during the transport cycle. Distance changes occurring between selected residues were monitored in the full transporter by site-directed spin-labeling electron paramagnetic resonance spectroscopy and site-directed chemical cross-linking...

Axonemal dyneins are force-generating ATPases that produce ciliary and flagellar movement. A dynein has large heavy chain(s) in which there are multiple (4-6) ATP-binding consensus sequences (P-loops) as well as intermediate and light chains, constituting a very large complex. We purified a monomeric form of dynein (dynein-a) that has at least three light chains from 14S dyneins of Tetrahymena ...

Paramecium represents a simple, eukaryotic model system to study the cellular effects of some neuroactive drugs. They respond to the agonist beta,gamma-methylene ATP with a transient depolarizing receptor potential, Ca(2+)-based action potentials and repetitive bouts of forward and backward swimming called 'avoiding reactions' (AR). In vivo [(32)P]ATP binding assays showed saturable [(32)P]ATP ...

Abstract Resistance remains the major clinical challenge for therapy of Philadelphia chromosome–positive (Ph+) leukemia. With exception ponatinib, all approved tyrosine kinase inhibitors (TKIs) are unable to inhibit common “gatekeeper” mutation T315I. Here we investigated therapeutic potential crizotinib, a TKI targeting ALK and ROS1 in non-small cell lung cancer patients, which inhibited also ...

The MHC class I peptide loading complex (PLC) facilitates the assembly of MHC class I molecules with peptides, but factors that regulate the stability and dynamics of the assembly complex are largely uncharacterized. Based on initial findings that ATP, in addition to MHC class I-specific peptide, is able to induce MHC class I dissociation from the PLC, we investigated the interaction of ATP wit...

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 i...

Multi-conformation continuum electrostatics (MCCE) was used to analyze various structures of the NS3 RNA helicase from the hepatitis C virus in order to determine the ionization state of amino acid side chains and their pK(a)s. In MCCE analyses of HCV helicase structures that lacked ligands, several active site residues were identified to have perturbed pK(a)s in both the nucleic acid binding s...

Anionic phospholipids modulate the activity of inwardly rectifying potassium channels (Fan, Z., and J.C. Makielski. 1997. J. Biol. Chem. 272:5388-5395). The effect of phosphoinositides on adenosine triphosphate (ATP) inhibition of ATP-sensitive potassium channel (K(ATP)) currents was investigated using the inside-out patch clamp technique in cardiac myocytes and in COS-1 cells in which the card...

The apparent DNA site size obtained from an assay monitoring the ATPase activity of Escherichia coli recA protein (n = 3.5) differs from that determined from a direct DNA binding assay (n = 7) done under identical conditions. Investigation of this discrepancy indicates that at a DNA:protein ratio of 3.5:1, one-half of the recA protein population is less sensitive to ATPase activity inhibition b...

The crystal structure of the MJ0796 ATP-binding cassette, a member of the o228/LolD transporter family, has been determined at 2.7-A resolution with MgADP bound at its active site. Comparing this structure with that of the ATP-bound form of the HisP ATP-binding cassette (Hung, L. W., Wang, I. X., Nikaido, K., Liu, P. Q., Ames, G. F., and Kim, S. H. (1998) Nature 396, 703-707) shows a 5-A withdr...