(Below N is a link to NCBI taxonomic web page and E link to ESTHER at designed phylum.) > cellular organisms: NE > Eukaryota: NE > Viridiplantae: NE > Streptophyta: NE > Streptophytina: NE > Embryophyta: NE > Tracheophyta: NE > Euphyllophyta: NE > Spermatophyta: NE > Magnoliophyta: NE > Mesangiospermae: NE > eudicotyledons: NE > Gunneridae: NE > Pentapetalae: NE > asterids: NE > lamiids: NE > Solanales: NE > Solanaceae: NE > Solanoideae: NE > Solaneae: NE > Solanum: NE > Lycopersicon: NE > Solanum lycopersicum: NE
LegendThis sequence has been compared to family alignement (MSA) red => minority aminoacid blue => majority aminoacid color intensity => conservation rate title => sequence position(MSA position)aminoacid rate Catalytic site Catalytic site in the MSA MAMLIEELIKSIEMWLKLIKKPQEYIDPTLDPVLLVPGVAGSILNAVDKK TGRTERVWVRILGADHEFCDKLWCRFDPSTGKTTNLDPDTSIEVPEDRYG LYAIDNLDPDMIIGSDCVYYYHDMIVEMLSWGYQEGKTLFGFGYDFRQSN RLQETMECFAQKLESIHTASGGKKINIISHSMGGLLVKCFMALHSDIFEK YVKNWIAIAAPFQGAPGYITSSLLNGTSFVHGWEERFFISKWSMHQLLIE CPSIYELMGCPDFHWEHAPVLEIWKEKSNSNGESSVVLESYSPLEAVSVY ELALANNKVTYNGEKISLPFNLELLKWANKTREILCHAKVPDKVKFYNIY GTNYETPHSVCYGSQNAPISDLQQLPFVQSNYISVDGDGTVPTESAKADG LKAEARVGVPGDHRGIVCDRHVFRVIKHWLRADHDPYYNPINDYVILPTS FDIERHHEKGLDVTSLREEWEIVSESQDGKENADSGKTKVGSISVSHVGD DNTTWEEAHATLIVHPKSEGKQHVELNAMSVSARA
During a search for cDNAs encoding plant sterol acyltransferases, we isolated four full-length cDNAs from Arabidopsis thaliana that encode proteins with substantial identity with animal lecithin : cholesterol acyltransferases (LCATs). The expression of one of these cDNAs, AtLCAT3 (At3g03310), in various yeast strains resulted in the doubling of the triacylglycerol content. Furthermore, a complete lipid analysis of the transformed wild-type yeast showed that its phospholipid content was lower than that of the control (void plasmid-transformed) yeast whereas lysophospholipids and free fatty acids increased. When microsomes from the AtLCAT3-transformed yeast were incubated with di-[1-14C]oleyl phosphatidylcholine, both the lysophospholipid and free fatty acid fractions were highly and similarly labelled, whereas the same incubation with microsomes from the control yeast produced a negligible labelling of these fractions. Moreover when microsomes from AtLCAT3-transformed yeast were incubated with either sn-1- or sn-2-[1-14C]acyl phosphatidylcholine, the distribution of the labelling between the free fatty acid and the lysophosphatidylcholine fractions strongly suggested a phospholipase A1 activity for AtLCAT3. The sn-1 specificity of this phospholipase was confirmed by gas chromatography analysis of the hydrolysis of 1-myristoyl, 2-oleyl phosphatidylcholine. Phosphatidylethanolamine and phosphatidic acid were shown to be also hydrolysed by AtLCAT3, although less efficiently than phosphatidylcholine. Lysophospatidylcholine was a weak substrate whereas tripalmitoylglycerol and cholesteryl oleate were not hydrolysed at all. This novel A. thaliana phospholipase A1 shows optimal activity at pH 6-6.5 and 60-65 degrees C and appears to be unaffected by Ca2+. Its sequence is unrelated to all other known phospholipases. Further studies are in progress to elucidate its physiological role.
