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The multiprotein replisome complex that replicates DNA has been extensively characterized in vitro, but its composition and architecture in vivo is unknown. Using millisecond single-molecule fluorescence microscopy in living cells expressing fluorescent derivatives of replisome components, we have examined replisome stoichiometry and architecture. Active(More)
Many essential cellular processes are carried out by complex biological machines located in the cell membrane. The bacterial flagellar motor is a large membrane-spanning protein complex that functions as an ion-driven rotary motor to propel cells through liquid media. Within the motor, MotB is a component of the stator that couples ion flow to torque(More)
The twin-arginine translocation (Tat) system transports folded proteins across the bacterial cytoplasmic membrane and the thylakoid membrane of plant chloroplasts. The essential components of the Tat pathway are the membrane proteins TatA, TatB, and TatC. TatA is thought to form the protein translocating element of the Tat system. Current models for Tat(More)
In the pathogenesis of dilated cardiomyopathy, cytoskeletal proteins play an important role. In this study, we analyzed titin expression in left ventricles of 19 control human donors and 9 severely diseased (nonischemic) dilated cardiomyopathy (DCM) transplant-patients, using gel-electrophoresis, immunoblotting, and quantitative RT-PCR. Both human-heart(More)
Before birth, the compliance of the heart is limited predominantly by extracardiac constraint. Reduction of this constraint at birth requires that myocardial compliance be determined mainly by the heart's own constituents. Because titin is a principal contributor to ventricular passive tension (PT), we studied the expression and mechanics of cardiac-titin(More)
SMC (structural maintenance of chromosome) proteins act ubiquitously in chromosome processing. In Escherichia coli, the SMC complex MukBEF plays roles in chromosome segregation and organization. We used single-molecule millisecond multicolor fluorescence microscopy of live bacteria to reveal that a dimer of dimeric fluorescent MukBEF molecules acts as the(More)
Titin is responsible for the passive elasticity of the muscle sarcomere. The mechanical properties of skeletal and cardiac muscle titin were characterized in single molecules using a novel dual optical tweezers assay. Antibody pairs were attached to beads and used to select the whole molecule, I-band, A-band, a tandem-immunoglobulin (Ig) segment, and the(More)
Projectin and kettin are titin-like proteins mainly responsible for the high passive stiffness of insect indirect flight muscles, which is needed to generate oscillatory work during flight. Here we report the mechanical properties of kettin and projectin by single-molecule force spectroscopy. Force-extension and force-clamp curves obtained from Lethocerus(More)
Most organisms are able to synthesize ATP by OXPHOS (oxidative phosphorylation). Mitochondria in eukaryotes perform OXPHOS in the inner mitochondrial membrane, whereas the plasma membrane is used by prokaryotes. However, whereas OXPHOS is a well-understood process at the biochemical level, relatively little is known about its operation at the level of the(More)
The cytochrome bd-I complex of Escherichia coli is a respiratory terminal oxidase and an integral component of the cytoplasmic membrane. As with other respiratory components, the organization and dynamics of this complex in living membranes is unknown. We set out to visualize the distribution and dynamics of this complex in vivo. By exchanging cydB for(More)