An Engineering Perspective on the Bacterial Flagellum: Part 2 – Analytic View

Abstract

Systems biology employs methodology and techniques typical of systems engineering. Similarly, reverse engineering of the features of biological organisms leverages both biology and engineering disciplines. The systems perspective on the bacterial flagellum detailed below studies the purpose, functions, components, and structure of a typical bacterial flagellum. The dynamic operation and control of this organelle and the flagellum’s assembly stages are also studied. The bacterial flagellum is a well-researched bacterial subsystem [1,2,3,4] in biology. However, this three-part engineering study takes two essentially independent approaches. First was a constructive approach, which was discussed in detail in Part 1 [5]; the other is an analytical approach, which is discussed in detail herein. The first, constructive approach was a top-down specification. That is, Part 1 started with specifying the purpose of a bacterial motility organelle, the environment of a bacterium, its existing resources, its existing constitution, and its physical limits, all within the relevant aspects of physics and molecular chemistry. From that, the constructive approach derived the logically necessary functional requirements, the constraints, the assembly needs, and the hierarchical relationships within the functionality. The functionality included a required control subsystem to properly direct the operation of a propulsion subsystem. Those functional requirements and constraints then suggested the few—and very limited—viable implementation schemata for a bacterial propulsion system. The details of one schema were then set forth. A sincere attempt was made to keep the elaboration of this constructive approach logical and as independent as possible from knowledge of the actual flagellar structure. The second, analytical approach employed here in Part 2 is the converse of the first approach; it is a bottom-up analysis. This Part 2 presents the constituent proteins, observed structure, assembly, and resultant behavior of a typical bacterium. This knowledge has been acquired by microscopic observation, by gene sequencing, by disabling component proteins Abstract