NORMAL GENOMIC

• Yu B, Wakao S, Fan J, Benning C
• Loss of plastidic lysophosphatidic acid acyltransferase causesembryo-lethality in Arabidopsis.
• Plant Cell Physiol. 2004; 45: 503-10
• Display abstract

• Phosphatidic acid is a key intermediate for chloroplast membrane lipidbiosynthesis. De novo phosphatidic acid biosynthesis in plants occurs intwo steps: first the acylation of the sn-1 position ofglycerol-3-phosphate giving rise to lysophosphatidic acid; second, theacylation of the sn-2 position of lysophosphatidic acid to formphosphatidic acid. The second step is catalyzed by a lysophosphatidic acidacyltransferase (LPAAT). Here we describe the identification of the ATS2gene of Arabidopsis encoding the plastidic isoform of this enzyme.Introduction of the ATS2 cDNA into E. coli JC 201, which istemperature-sensitive and carries a mutation in its LPAAT gene plsC,restored this mutant to nearly wild type growth at high temperature. Agreen-fluorescent protein fusion with ATS2 localized to the chloroplast.Disruption of the ATS2 gene of Arabidopsis by T-DNA insertion causedembryo lethality. The development of the embryos was arrested at theglobular stage concomitant with a transient increase in ATS2 geneexpression. Apparently, plastidic LPAAT is essential for embryodevelopment in Arabidopsis during the transition from the globular to theheart stage when chloroplasts begin to form.

• Buchner G et al.
• Identification of a new EGF-repeat-containing gene from human Xp22: acandidate for developmental disorders.
• Genomics. 2000; 65: 16-23
• Display abstract

• Epidermal growth factor (EGF) repeat-containing proteins constitute anexpanding family of proteins involved in several cellular activities suchas blood coagulation, fibrinolysis, cell adhesion, and neural andvertebrate development. By using a bioinformatic approach, we haveidentified a new member of this family named MAEG (MAM- and EGF-containinggene; HGMW-approved gene symbol and gene name). Sequence analysisindicates that MAEG encodes a secreted protein characterized by thepresence of five EGF repeats, three of which display a Ca(2+)-bindingconsensus sequence. In addition, a MAM domain is also present at theC-terminus of the predicted protein product. The human and murinefull-length cDNAs were identified and mapped to human Xp22 and to themouse syntenic region. Northern analysis indicates that MAEG is expressedearly during development. Taken together, these data render MAEG acandidate for human and murine developmental disorders.

• Bouvier-Nave P, Benveniste P, Oelkers P, Sturley SL, Schaller H
• Expression in yeast and tobacco of plant cDNAs encoding acylCoA:diacylglycerol acyltransferase.
• Eur J Biochem. 2000; 267: 85-96
• Display abstract

• During the course of a search for cDNAs encoding plant sterolacyltransferases, an expressed sequence tag clone presenting substantialidentity with yeast and animal acyl CoA:cholesterol acyltransferases wasused to screen cDNA libraries from Arabidopsis and tobacco. This resultedin the isolation of two full-length cDNAs encoding proteins of 520 and 532amino acids, respectively. Attempts to complement the yeast double-mutantare1 are2 defective in acyl CoA:cholesterol acyltransferase wereunsuccessful, showing that neither gene encodes acyl CoA:cholesterolacyltransferase. Their deduced amino acid sequences were then shown tohave 40 and 38% identity, respectively, with a murine acylCoA:diacylglycerol acyltransferase and their expression in are1 are2 orwild-type yeast resulted in a strong increase in the incorporation ofoleyl CoA into triacylglycerols. Incorporation was 2-3 times higher inmicrosomes from yeast transformed with these plant cDNAs than in yeasttransformed with the void vector, clearly showing that these cDNAs encodeacyl CoA:diacylglycerol acyltransferases. Moreover, during the preparationof microsomes from the Arabidopsis DGAT-transformed yeast, a floatinglayer was observed on top of the 100 000 g supernatant. This fraction wasenriched in triacylglycerols and exhibited strong acyl CoA:diacylglycerolacyltransferase activity, whereas almost no activity was detected in thecorresponding clear fraction from the control yeast. Thanks to the use ofthis active fraction and dihexanoylglycerol as a substrate, the de novosynthesis of 1,2-dihexanoyl 3-oleyl glycerol by AtDGAT could bedemonstrated. Transformation of tobacco with AtDGAT was also performed.Analysis of 19 primary transformants allowed detection, in severalindividuals, of a marked increase (up to seven times) of triacylglycerolcontent which correlated with the AtDGAT mRNA expression. Furthermore,light-microscopy observations of leaf epidermis cells, stained with alipid-specific dye, showed the presence of lipid droplets in the cells oftriacylglycerol-overproducer plants, thus illustrating the potentialapplication of acyl CoA:diacylglycerol acyltransferase-transformed plants.

• Copley RR
• The gene for X-linked anhidrotic ectodermal dysplasia encodes a TNF-likedomain.
• J Mol Med. 1999; 77: 361-3