| 19050080 |
Qudeimat E, Faltusz AM, Wheeler G, Lang D, Brownlee C, Reski R, Frank W: A PIIB-type Ca2+-ATPase is essential for stress adaptation in Physcomitrella patens. Proc Natl Acad Sci U S A. 2008 Dec 9;105(49):19555-60. Epub 2008 Dec 2.
Transient cytosolic Ca (2+) ([Ca (2+)](cyt)) elevations are early events in plant signaling pathways including those related to abiotic stress. The restoration of [Ca (2+)](cyt) to prestimulus levels involves ATP-driven Ca (2+) pumps, but direct evidence for an essential role of a plant Ca (2+)-ATPase in abiotic stress adaptation is missing. Here, we report on a stress-responsive Ca (2+)-ATPase gene (PCA1) from the moss Physcomitrella patens. Functional analysis of PCA1 in a Ca (2+) transport-deficient yeast mutant suggests that PCA1 encodes a P (IIB)-type Ca (2+)-ATPase harboring an N-terminal autoinhibitory domain. In vivo localizations identified membranes of small vacuoles as the integration site for a PCA1:GFP fusion protein. PCA1 mRNA levels are up-regulated by dehydration, NaCl, and abscisic acid, and PCA1 loss-of-function mutants (DeltaPCA1) exhibit an enhanced susceptibility to salt stress. The DeltaPCA1 lines show sustained elevated [Ca (2+)](cyt) in response to salt treatment in contrast to WT that shows transient Ca (2+) elevations, indicating a direct role for PCA1 in the restoration of prestimulus [Ca (2+)](cyt). The altered Ca (2+) response of the DeltaPCA1 mutant lines correlates with altered expression levels of stress-induced genes, suggesting disturbance of a stress-associated signaling pathway. We propose that PCA1 is an essential component for abiotic stress adaptation in Physcomitrella involved in the generation of a specific salt-induced Ca (2+) signature. |
85(1,1,1,5) |