PgmNr W4127: Metablomics meets genomics in Pristionchus pacificus: A highly specific esterase is involved in the synthesis of dauer inducing small molecules.

Authors:
J. M. Meyer 1 ; N. Bose 2 ; J. Y. Yim 2 ; A. Artyukhin 2 ; F. C. Schroeder 2 ; R. J. Sommer 1


Institutes
1) Max-Planck Institute for Developmental Biology, Tuebingen, DE; 2) Boyce Thompson Institute, Cornell University, New York, USA.


Keyword: Other ( Dauer Development )

Abstract:

All animals have evolved abilities to react towards changes in their environments. Nematodes for example, can arrest their development under adverse environmental conditions and enter a long-lived, stress-resistant “dauer” stage. This “dauer stage” plays a major role as survival but also as dispersal strategy of nematodes. Small molecules are crucial for the regulation of dauer entry and additionally, have been shown to function as cues in chemical communication through which they can regulate complex behaviors. Recent studies in Pristionchus pacificus and comparison to Caenorhabditis elegans indicated that small molecule structure and function evolve rapidly. One hallmark is that small molecule structures in P. pacificus are far more complex than their C. elegans analogs. Also, the collection of worldwide isolates of P. pacificus provided strong evidence for extreme natural variation of these pheromones across genotypes. In this context, a new type of intraspecific competition among sympatric strains was identified with a new role of small molecules in nematode evolutionary ecology. Thus, small molecules are important for the regulation, ecology and evolution of dauer development. Despite this, very little is known about the enzymes and pathways involved in the synthesis of small molecules. Here, we study intra-species variation in small molecules production in P. pacificus on La Réunion Island. In the last 5 years, we extensively sampled a nematode population by collecting more than 300 local strains, which were subsequently characterized through a combination of genomic (RAD-sequencing) and secrotomic (HPLC/MS/MS) approaches. We found that these highly related strains still showed massive differences in their small molecule secretomes. Most importantly, ubas#1 and ubas#2, two compounds shown to play a crucial role in dauer regulation, were absent from a certain number of strains. Combining both datasets we were able to utilize genome-wide association studies (GWAS) to identify a candidate region. Using nanopore and whole genome re-sequencing we confirmed the identity of the causative gene as a putative esterase that is involved in the synthesis of ubas#1 and ubas#2. We used the CRISPR/CAS9 system to inactivate the esterase-encoding gene and found the resulting mutant to be ubas#1 and ubas#2 deficient. Thus, through a multifaceted experimental approach we have identified a key enzyme involved in the synthesis of complex, dauer-inducing small molecules in P. pacificus.