Metabolic and Genetic Basis for Auxotrophies in Gram-Negative Species
Metabolic and genetic basis for auxotrophies in Gram-negative species Yara Seifa,1 , Kumari Sonal Choudharya,1 , Ying Hefnera, Amitesh Ananda , Laurence Yanga,b , and Bernhard O. Palssona,c,2 aSystems Biology Research Group, Department of Bioengineering, University of California San Diego, CA 92122; bDepartment of Chemical Engineering, Queen’s University, Kingston, ON K7L 3N6, Canada; and cNovo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Lyngby, Denmark Edited by Ralph R. Isberg, Tufts University School of Medicine, Boston, MA, and approved February 5, 2020 (received for review June 18, 2019) Auxotrophies constrain the interactions of bacteria with their exist in most free-living microorganisms, indicating that they rely environment, but are often difficult to identify. Here, we develop on cross-feeding (25). However, it has been demonstrated that an algorithm (AuxoFind) using genome-scale metabolic recon- amino acid auxotrophies are predicted incorrectly as a result struction to predict auxotrophies and apply it to a series of the insufficient number of known gene paralogs (26). Addi- of available genome sequences of over 1,300 Gram-negative tionally, these methods rely on the identification of pathway strains. We identify 54 auxotrophs, along with the corre- completeness, with a 50% cutoff used to determine auxotrophy sponding metabolic and genetic basis, using a pangenome (25). A mechanistic approach is expected to be more appropriate approach, and highlight auxotrophies conferring a fitness advan- and can be achieved using genome-scale models of metabolism tage in vivo. We show that the metabolic basis of auxotro- (GEMs). For example, requirements can arise by means of a sin- phy is species-dependent and varies with 1) pathway structure, gle deleterious mutation in a conditionally essential gene (CEG), 2) enzyme promiscuity, and 3) network redundancy.
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