In this paper, researchers from Oxford, Japan, and China wanted to know if the rotation speed was affected by the number of stator units. Previous work had suggested that flagella could rotate at full speed independently of stator subunit count. Through a series of precise measurements on flagella from different bacterial species mutated to vary the number, here’s what they found:
"The bacterial flagellar motor is a rotary molecular motor responsible for swimming, swarming, and chemotaxis in many species of bacteria. It generates torque by interactions between a rotor 50 nm in diameter and multiple stator units. We overturn the prevailing understanding of how stator units interact with each other by showing that motor speed is dependent on the number of stator units even at high speed near zero torque."
As mentioned in Unlocking, bacteria can reverse the direction of rotation rapidly. The propeller itself, though, must also quickly adjust its protein subunits to “supercoil” in the opposite direction. Here’s news: the supercoiling is required for function. That fact inspired some machine language, found in this paper in Nature Communications:
"The bacterial flagellar filament has been intensively studied for many years. It has served as an enlightening system for understanding how a protein polymer composed of a single protein, flagellin (except for the cap protein at the end that acts as an assembling chaperone) switches among different states to supercoil. This supercoiling allows the rotating filament to behave as an Archimedean screw and produce thrust. The filament can adopt different conformational states due to mechanical forces, such as when the motor switches the sense of rotation, allowing the bacteria to swim forward, backward, in a screw-like fashion and to tumble."
As Behe had pointed out, mutations to essential parts of an irreducibly complex system can lead to loss of function:
"With the motor linked to sensory receptors, the bacteria are capable of moving towards nutrients and away from dangerous environments, resulting in a significant survival advantage. On the other hand, mutations within the flagellin protein that fail to form supercoiled filaments generate no thrust when such straight filaments are rotated, leading to non-motile bacteria."
Here we find another critical detail that wasn’t known before: 
a straight filament won’t work. It has to supercoil, so it can function like an Archimedean screw.
*The proteins must be packed just right so that they will not only supercoil, but quickly change between left and right orientations in a process called “polymorphic switching.”
*The proteins must be packed just right so that they will not only supercoil, but quickly change between left and right orientations in a process called “polymorphic switching.”
*Notice how finely tuned this architecture is. If it’s not tightly balanced, it won’t work!
Another paper in PNAS investigates bacteria in the Vibrio genus with sheathed flagella, which have not been studied as much as the unsheathed forms like in E. coli. Let’s listen to their praise of these molecular motors in their introduction:
The flagellum is a large macromolecular assembly composed of a long filament, a hook, and a motor.
Another paper in PNAS investigates bacteria in the Vibrio genus with sheathed flagella, which have not been studied as much as the unsheathed forms like in E. coli. Let’s listen to their praise of these molecular motors in their introduction:
"A sophisticated chemotactic signaling system allows the bacterium to sense chemical stimuli and effectively swim toward favorable environments by a biased random walk, a combination of “runs” and “tumbles”."
The flagellum is a large macromolecular assembly composed of a long filament, a hook, and a motor.
The flagellar motor is a remarkable nanomachine embedded in the bacterial cell envelope. More than 20 different proteins are required for the assembly of the motor, which can be divided into several morphological domains.
---The MS ring is embedded in the cytoplasmic membrane. 
---The C ring, known as the switch complex, and the export apparatus are located in the cytoplasmic side of the MS ring.
---The rod connects the MS ring and the hook and is commonly divided into the distal rod and the proximal rod.
---The L and P rings on the rod function as bushings at the outer membrane and at the peptidoglycan layer, respectively.
The stator is the torque generator embedded in the cytoplasmic membrane…. Powered by the proton motive force, the stator
generates the torque required to rotate the motor, the hook, and the filament. The stator shares several common features despite the difference in ions and proteins involved.
Typically, multiple stator units work together, although a single stator is enough to generate rotational torque. Stepwise photo-bleaching of a functioning motor region revealed that the stator is highly dynamic and can associate into or dissociate from the rotor rapidly.
Recent reports revealed that the stator–rotor association is dependent on conducting ions and torque load.
The authors found new parts in the sheathed flagella motor, which might not be surprising given the higher performance demands.
They found
*a T-ring, with 13-fold symmetry, which seems to increase torque;
*an H-ring, which is apparently essential during motor assembly;
*and an O-ring, which seems to help build the sheath.
They found
*a T-ring, with 13-fold symmetry, which seems to increase torque;
*an H-ring, which is apparently essential during motor assembly;
*and an O-ring, which seems to help build the sheath.
These new parts are all intricately tied into the motor, just as you would expect hub lockers, the transfer case and redesigned differentials to be built to coordinate with all the other parts in a 4-wheel-drive vehicle. The diagrams of these new parts are really stunning."
EN&V
Thank You for making me so wonderfully complex!
Your workmanship is marvelous...
Psalm 139:14 NLT
For the invisible things of Him from the creation
of the world are clearly seen,
... so that they are without excuse:
Romans 1:20
