Lack of mitochondrial anionic phospholipids causes an inhibition of translation of protein components of the electron transport chain. A yeast genetic model system for the study of anionic phospholipid function in mitochondria.
Reduction of mitochondrial cardiolipin (CL) levels has been postulated to compromise directly the function of several essential enzymes and processes of the mitochondria. There is limited genetic evidence for the critical roles with which CL and its precursor phosphatidylglycerol (PG) have been associated. A null allele of the PGS1 gene from Saccharomyces cerevisiae, which encodes the enzyme responsible for the synthesis of the CL precursor PG phosphate, was created in a yeast strain in which PGS1 expression is exogenously regulated by doxycycline. The addition of increasing concentrations of doxycycline to the growth medium causes a proportional decrease to undetectable levels of PGS1 transcript, PG phosphate synthase activity, and PG plus CL. The doubling time of this strain with increasing doxycycline increases to senescence in non-fermentable carbon sources or at high temperatures, conditions that do not support growth of the pgs1Delta strain. Doxycycline addition also causes mitochondrial abnormalities as observed by fluorescence microscopy. Products of four mitochondrial encoded genes (COX1, COX2, COX3, and COB) and one nuclear encoded gene (COX4) associated with the mitochondrial inner membrane are not present when PGS1 expression is fully repressed. No translation of these proteins can be detected in cells lacking the PGS1 gene product, although transcription and splicing appear unaffected. Protein import of other nuclear encoded proteins remains unaffected. The remaining proteins encoded by mitochondrial DNA are expressed and translated normally. Thus, the molecular basis for the lack of mitochondrial function in pgs1Delta cells is the failure to translate gene products essential to the electron transport chain.
Ostrander
D B
DB
Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston, TX 77225, USA.
Zhang
M
M
Mileykovskaya
E
E
Rho
M
M
Dowhan
W
W
D000165:Acridine Orange / Q000031:analogs & derivatives; D000838:Anions / Q000378:metabolism*; D001483:Base Sequence; D004396:Coloring Agents; D051545:Cyclooxygenase 1; D004318:Doxycycline / Q000494:pharmacology; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000235:genetics; D005947:Glucose / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics; D010957:Plasmids; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics; D014176:Protein Biosynthesis; D006180:Proton-Translocating ATPases / Q000302:isolation & purification / Q000378:metabolism; D011726:Pyridinium Compounds; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D013696:Temperature; D017855:Transferases (Other Substituted Phosphate Groups) / Q000235:genetics* / Q000502:physiology
D000838:Anions; D004396:Coloring Agents; D007527:Isoenzymes; D008565:Membrane Proteins; D010743:Phospholipids; D010940:Plant Proteins; D011726:Pyridinium Compounds; D029701:Saccharomyces cerevisiae Proteins; C111957:cox2 protein, Glycine soja; C011786:2-(4-(dimethylamino)styryl)-1-methylpyridinium; C056258:N(10)-nonylacridine orange; D051545:Cyclooxygenase 1; D011451:Prostaglandin-Endoperoxide Synthases; C093750:COX3 protein, S cerevisiae; D003576:Electron Transport Complex IV; D017855:Transferases (Other Substituted Phosphate Groups); C020676:CDP-diacylglycerol-glycerol-3-phosphate 3-phosphatidyltransferase; D006180:Proton-Translocating ATPases; D000165:Acridine Orange; D005947:Glucose; D004318:Doxycycline