The terpenoid theory of the origin of cellular life: the evolution of terpenoids to cholesterol

Possibility of Bacterial Recruitment of Plant Genes Associated with the Biosynthesis of Secondary Metabolites

“…Nevertheless, the physiological function of hopanoids is only poorly understood (Kannenberg and Poralla, 1999), although it is known that they are formed during transition from substrate to aerial hyphae in S. coelicolor A3(2) (Poralla et al, 2000). The strong hydrophobicity of both classes of triterpenoids suggests they are located in the membranes and might be involved in controlling membrane fluidity and rigidity (Ourisson and Nakatani, 1994). Even though myx- obacteria contain a sufficiently wide variety of different fatty acids to fine tune their membrane fluidity (Ware and Dworkin, 1973;Mahmud et al, 2002), steroids may also play a role.…”

Bendigoles A~C, New Steroids from Gordonia australis Acta 2299

“…Steroids are ubiquitous cell constituents in eukaryotes which control the fluidity and flexibility of the cell membranes [8], whereas prokaryotes contain hopanoids, pentacyclic terpenes, which have the same function as steroids [9]. However, some reports demonstrate the presence of steroids in bacterial cells [10].…”

5. Prebiotic Chemistry – Biochemistry – Emergence of Life (4.4–2 Ga)

“…This membrane heredity view (Cavalier-Smith, 2001) together with the heuristic principle of continuity (Morowitz et al, 1991) would conform to the idea that some type of amphiphilic bilayer existed since early times and that a kind of continuum allowed its evolution to date. Within this framework, amphiphiles and vesicles would be key chemical intermediates during life emergence (Ourisson and Nakatani, 1994;Luisi et al, 1999;Segre´et al, 2001). …”