Are the Arginine Kinase functions found in Myxococcus xanthus conserved in a sister species, Myxococcus macrosporus?

Name: Seula Kim
Major: Biology
Advisors: Dean Fraga, Laura Sirot

Phosphagen kinases (PK) catalyze the reversible phosphorylation of the guanidino substrate to buffer energy in all animal species and some protozoa. Recently, genomic sequencing of bacterial species has revealed that a few of them contain arginine kinases (AK) that phosphorylate arginine and utilize ATP as an energy buffering system. Phylogenetic evidence indicates that closely related bacterial species that carry AK are missing AK homologs, suggesting that these bacterial AK (bAK) are derived through horizontal gene transfer (HGT). Among these bacterial species, the bAK found in Myxococcus xanthus (MxAK) was shown to play unique roles in social and developmental behaviors, such as kin discrimination and fruiting body formation. In this study, the role of bAK in Myxococcus macrosporus, a bacterial species that is closely related to M.xanthus, was studied to determine if the bAK in that species had similar roles in social and developmental behaviors. If the AK of M.macrosporus (MmAK) exhibits the same role as MxAK, this might indicate that both species inherited AK from their common ancestor with roles in these behaviors. If MmAK is not responsible for such behaviors, it suggests that MxAk has evolved new functions after getting transmitted to M.xanthus through HGT. We first characterized the basic growth and social behaviors of M.macrosporus to compare to M.xanthus. Several attempts were made to create the MmAK deletion, but the plasmid sequence would not recombine out of the genome, exhibiting very low frequency of plasmid excision compared to MmAK gene. As a consequence, we used the strain that contained the ∆AK construct in addition to the MmAK gene. Both the WT and ∆AK strain exhibited fruiting bodies, but they formed a strict border towards each other, indicating that ∆AK in M.macrosporus may participate in the kin recognition.

Posted in Comments Enabled, Independent Study, Symposium 2023 on April 14, 2023.

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