Small Things Considered

Fine Reading: A Quick Guide to the Bacterial Flagellar Motor

by Elio

Schematic diagram of the flagellar motor.
The flagellar motor is a macromolecular
assembly made of approximately 20
different proteins. It extends from the
cell interior (bottom) to the exterior
(top), spanning across three membranes:
first the cytoplasmic membrane, then
the peptidoglycan layer, and lastly the
outer membrane. Its components are
termed the rotor, stators, drive shaft,
bushing, rotation-switch regulator, and
so on. Source.

The bacterial flagellar motor deserves great write-ups. Hardly anything in biology is more fascinating than this marvel of miniaturization. Not surprisingly, this smallest and most perfect of electric motors has a worthy advocate. Howard C. Berg of Harvard, who has himself contributed a great deal to our understanding of how the flagellar motor works, has written a short but powerful précis in Current Biology. It will take you but ten minutes to read it, unless you pause and think about the many gems therein.

Structural Grace II

In her autobiography in the 2007 Annual Review of Microbiology, Margarita Salas published an electron micrograph of rare beauty. It shows the DNA of phage ø29 casually coiled around itself, with protein TP (for Terminal Protein) at the two ends. Not only is this a fine demonstration of a specific DNA-protein interaction, but the surprisingly symmetrical spiral of the DNA invites speculation about how it coiled itself so elegantly. Any ideas?

Source: Margarita Salas (2007) 40 Years with Bacteriophage ø29.
Annual Review of Microbiology 61: 1-22.
Photo by José M. Sogo