The Golgi α-1,6 mannosyltransferase KlOch1p of Kluyveromyces lactis is required for Ca2+/calmodulin-based signaling and for proper mitochondrial functionality
1 Dpt. Developmental and Cell Biology, University LA SAPIENZA, P.le A. Moro,5 00185 Rome, Italy
2 Pasteur Insitute-Fondazione Cenci Bolognetti, LA SAPIENZA, Rome, Italy
3 Dpt. Experimental Medicine, University LA SAPIENZA, Rome, Italy
4 National Centre for Rare Diseases, Istituto Superiore di Sanità, Rome, Italy
5 Institut de Génétique et Microbiologie, UMR8621, Université Paris-Sud, 91405 Orsay Cedex, France
BMC Cell Biology 2009, 10:86 doi:10.1186/1471-2121-10-86Published: 14 December 2009
Protein N-glycosylation is a relevant metabolic pathway in eukaryotes and plays key roles in cell processes. In yeasts, outer chain branching is initiated in the Golgi apparatus by the alpha-1,6-mannosyltransferase Och1p.
Here we report that, in Kluyveromyces lactis, this glycosyltransferase is also required to maintain functional mitochondria and calcium homeostasis. Cells carrying a mutation in KlOCH1 gene showed altered mitochondrial morphology, increased accumulation of ROS and reduced expression of calcium signalling genes such as calmodulin and calcineurin. Intracellular calcium concentration was also reduced in the mutant cells with respect to the wild type counterparts.
Phenotypes that occur in cells lacking the alpha-1,6-mannosyltransferase, including oxidative stress and impaired mitochondria functionality, were suppressed by increased dosage of KlCmd1p. This, in turn, acts through the action of calcineurin.
Proper functioning of the alpha-1,6-mannosyltransferase in the N-glycosylation pathway of K. lactis is required for maintaining normal calcium homeostasis; this is necessary for physiological mitochondria dynamics and functionality.