Characterization of a Listeria monocytogenes Ca(2+) pump: a SERCA-type ATPase with only one Ca(2+)-binding site.
We have characterized a putative Ca(2+)-ATPase from the pathogenic bacterium Listeria monocytogenes with the locus tag lmo0841. The purified and detergent-solubilized protein, which we have named Listeria monocytogenes Ca(2+)-ATPase 1 (LMCA1), performs a Ca(2+)-dependent ATP hydrolysis and actively transports Ca(2+) after reconstitution in dioleoylphosphatidyl-choline vesicles. Despite a high sequence similarity to the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA1a) and plasma membrane Ca(2+)-ATPase (PMCA), LMCA1 exhibits important biochemical differences such as a low Ca(2+) affinity (K(0.5) ∼80 μm) and a high pH optimum (pH ∼9). Mutational studies indicate that the unusually high pH optimum can be partially ascribed to the presence of an arginine residue (Arg-795), corresponding in sequence alignments to the Glu-908 position at Ca(2+) binding site I of rabbit SERCA1a, but probably with an exposed position in LMCA1. The arginine is characteristic of a large group of putative bacterial Ca(2+)-ATPases. Moreover, we demonstrate that H(+) is countertransported with a transport stoichiometry of 1 Ca(2+) out and 1 H(+) in per ATP hydrolyzed. The ATPase may serve an important function by removing Ca(2+) from the microorganism in environmental conditions when e.g. stressed by high Ca(2+) and alkaline pH.
Department of Molecular Biology, Gustav Wieds Vej 10C, Denmark.
Kristina
K
Faxén
Jacob Lauwring
JL
Andersen
Pontus
P
Gourdon
Natalya
N
Fedosova
Jens Preben
JP
Morth
Poul
P
Nissen
Jesper Vuust
JV
Møller
D000255:Adenosine Triphosphate / Q000378:metabolism; D000468:Alkalies / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000502:physiology; D001693:Biological Transport, Active / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D055664:Electrochemical Techniques; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000201:enzymology* / Q000235:genetics*; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000201:enzymology; D017434:Protein Structure, Tertiary; D011817:Rabbits; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D000468:Alkalies; D000255:Adenosine Triphosphate; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D002118:Calcium