Auto‐inhibition of Arabidopsis thaliana plasma membrane Ca2+‐ATPase involves an interaction of the N‐terminus with the small cytoplasmic loop

• Published in: FEBS letters Vol. 574; no. 1-3; pp. 20 - 24
• Main Authors: Luoni, Laura, Meneghelli, Silvia, Bonza, Maria Cristina, DeMichelis, Maria Ida
• Format: Journal Article
• Language: English
• Published: England 10-09-2004
• Subjects: aa, aminoacids; Amino Acid Sequence; Arabidopsis - enzymology; Arabidopsis thaliana; Auto-inhibition; Base Sequence; Ca2+-ATPase; Calcium-Transporting ATPases - antagonists & inhibitors; Calcium-Transporting ATPases - chemistry; Calmodulin; CaM, calmodulin; Cell Membrane - enzymology; Cytoplasm - metabolism; DNA Primers; Intramolecular interaction; Molecular Sequence Data; Plasma membrane; PM, plasma membrane; Sequence Homology, Amino Acid; TM, transmembrane domain
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/j.febslet.2004.08.003

Type IIB Ca2+‐ATPases have a terminal auto‐inhibitory, domain the action of which is suppressed by calmodulin (CaM) binding. Here, we show that a peptide (6His‐1M‐I116) corresponding to the first 116 aminoacids (aa) of At‐ACA8, the first cloned isoform of Arabidopsis thaliana plasma membrane Ca2+‐ATPase, inhibits the activity of the enzyme deprived of the N‐terminus by controlled trypsin treatment 10‐fold more efficiently than a peptide (41I‐T63) corresponding only to the CaM‐binding site. A peptide (268E‐W348) corresponding to 81 aa of the small cytoplasmic loop of At‐ACA8 binds peptide 6His‐1M‐I116 immobilized on Ni–NTA agarose. Peptide 268E‐W348 stimulates Ca2+‐ATPase activity. Its effect is not additive with that of CaM and is suppressed by tryptic cleavage of the N‐terminus. These results provide the first functional identification of a site of intramolecular interaction with the terminal auto‐inhibitory domain of type IIB Ca2+‐ATPases.