Listeria Monocytogenes Lmo0818 - Exploring a Putative Ca2+-ATPase, to Understand Calcium Ion Specificity

This project focus on calcium homeostasis in the opportunistic pathogenic bacteria Listeria monocytogenes. Genomic analysis of L. monocytogenes identifies two P-type ATPases with putative selectivity for Calcium transport (Lmo0841 and Lmo0818). Lmo0841 was recently confirmed as a Ca2+ -ATPase, able to transport a single Calcium ion per hydrolyzed ATP the L. monocytogenes Ca2+ -ATPase was consequently named LMCA1 [1] Sequence analysis and homology modeling strongly suggest that Lmo818 is a Ca2+ATPase with high similarity to the plasma membrane ATPases (PMCA), a type IIb P-type ATPase from higher eukaryotes. There is no X-ray structures of any PMCA's determined, they are known to be less stabile in comparison with the sarco(endo)plasmic reticulum Ca2+ -ATPases (SERCA) and also often require additional soluble factors to function, like the necessity of Calmodulin to the PMCA [2]. We have determined the structure to 2.7 A resolution initial structural comparison indicate a similar fold to SERCA, however with significantly reduced loop regions. A comparative bioinformatics study will be presented based on Lmo0818 that reveal how the pumps are could act as receptors in prokaryotic membrane systems as compared to ion recognition and receptor function found in the Na+,K+ -ATPase [3].[1]Faxen, K., et al. (2011). J. Biol. Chem. 286, 1609-1617.[2]Niggli, V.et al. J. Biol. Chem. 256, 8588-8592.[3]Morth, J.P., et al. Nat. Rev. Mol. Cell Biol. 12, 60-70.