The biosynthetic diversity of the animal world

Abstract

Secondary metabolites are often considered within the remit of bacterial or plant research, but animals also contain a plethora of these molecules with important functional roles. Classical feeding studies demonstrate that, whereas some are derived from diet, many of these compounds are made within the animals. In the past 15 years, the genetic and biochemical origin of several animal natural products has been traced to partnerships with symbiotic bacteria. More recently, a number of animal genome-encoded pathways to microbe-like natural products have come to light. These pathways are sometimes horizontally acquired from bacteria, but more commonly they unveil a new and diverse animal biochemistry. In this review, we highlight recent examples of characterized animal biosynthetic enzymes that reveal an unanticipated breadth and intricacy in animal secondary metabolism. The results so far suggest that there may be an immense diversity of animal small molecules and biosynthetic enzymes awaiting discovery. This biosynthetic dark matter is just beginning to be understood, providing a relatively untapped frontier for discovery.

Animal biosynthesis of complex polyketides in a photosynthetic partnership

“…We also sought other animal enzymes that might be methylmalonate specific, since insects and many other animals contain branched polyketides and lipids 10 , and yet the genes that might produce these have not been characterized. So far, we found the methylmalonate motif discovered in EcPKS1 in only two other sequenced animal transcriptomes: from the hemichordate Saccoglossus kowalevskii and the beetle Leptinotarsa decemlineata.…”

“…However, because of these data, it is often claimed that complex natural products such as polyketides must be made by symbiotic bacteria, despite a lack of evidence for most compounds found in nature. Although increasing evidence suggests that animals themselves make some compounds [6][7][8][9][10] , the origin of most polyketides in animals remains unknown. This problem makes it difficult to supply useful animal compounds as drugs and severely constrains our understanding of chemical diversity and the scope of biosynthesis in nature.…”

Secondary Metabolites of the Genus Didemnum: A Comprehensive Review of Chemical Diversity and Pharmacological Properties

“…In many of those cases, the hosts themselves may likely synthesize many of the compounds, rather than symbiotic bacteria. Biosynthesis of secondary metabolites by animal biochemistry is a barely explored, blooming field [93]. In those cases, in contrast to finding pathways from symbiotic bacteria, the tool required is transcriptomics, so that genes expressed by the animal are analyzed and subsequently their products are biochemically characterized [94].…”

Microbially Mediated Chemical Ecology of Animals: A Review of Its Role in Conspecific Communication, Parasitism and Predation

“…Interestingly, evidence of bacteria living within exocrine glands of animals is accumulating [ 15 , 16 , 17 , 22 , 23 , 29 , 30 ] and, thus, some of these endogenously produced chemicals may have a bacterial origin, a possibility that has been scarcely explored. The role of bacteria in the production of these chemicals is a recently opened line of research with promising future possibilities, and different studies have provided evidence for these mutualistic associations in different taxa [ 41 , 123 , 124 , 125 , 126 ].…”