Genome-wide screening reveals a novel class of carbonic anhydrase-like inorganic carbon transporters in chemoautotrophic bacteria

Desmarais, J. J.; Flamholz, A. I.; Blikstad, C.; Dugan, E. J.; Laughlin, T. G.; Oltrogge, L. M.; Wetmore, K.; Wang, J. Y.; Savage, D. F.

doi:10.1101/476713

bioRxiv · 10.1101/476713

Genome-wide screening reveals a novel class of carbonic anhydrase-like inorganic carbon transporters in chemoautotrophic bacteria

Desmarais, J. J.·Flamholz, A. I.·Blikstad, C.·Dugan, E. J.·Laughlin, T. G.·Oltrogge, L. M.·Wetmore, K.·Wang, J. Y.·Savage, D. F.

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Abstract

Many bacterial autotrophs rely on CO2 concentrating mechanisms (CCMs) to assimilate carbon. Although many CCM proteins have been identified, including a 200+ MDa protein organelle called the carboxysome, a systematic screen of CCM components has not been carried out. Here, we performed a genome-wide barcoded transposon screen to identify essential and CCM-related genes in the {gamma}-proteobacterium H. neapolitanus. Our screen revealed an operon encoding a domain of unknown function (PFAM:PF10070) and putative cation transporter subunit (PFAM:PF00361) is critical for CCM function. These two proteins, which we name DabA and DabB for \"DABs accumulate bicarbonate,\" function as a heterodimeric, energy-coupled inorganic carbon pump in E. coli. Furthermore, DabA has distant homology to a {beta}-carbonic anhydrase and binds a zinc ion necessary for activity. Based on these results, we propose that DABs function as vectorial CAs coupled to cation gradients and serve as inorganic carbon pumps throughout prokaryotic phyla.

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Desmarais, J. J., Flamholz, A. I., Blikstad, C., Dugan, E. J., Laughlin, T. G., Oltrogge, L. M., Wetmore, K., Wang, J. Y., Savage, D. F.. 2018-11-22. Genome-wide screening reveals a novel class of carbonic anhydrase-like inorganic carbon transporters in chemoautotrophic bacteria. https://doi.org/10.1101/476713

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