Disease relevance of SQS1

• Another E. coli extract expressing mouse squalene synthase showed the same activity as the Arabidopsis enzyme [1].
• Comparison of the Botryococcus SS (BSS) with SS from different organisms showed 52% identity with Nicotiana tabacum, 51% with Arabidopsis thaliana, 48% with Zea mays, 40% with rat, 39% with yeast, and 26% with Zymomonas mobilis [2].

High impact information on SQS1

• A gene encoding a class III SS from the Arabidopsis genome sequencing project shows a strongly conserved exon structure to the wheat ss3 gene, with the exception of the N-terminal region [3].
• In an attempt to better understand the regulation involved in the production of squalene and botryococcene, we have isolated and characterized a squalene synthase (SS) gene from the B race of B. braunii [2].
• Using this putative SS fragment as a probe, a 2632-bp cDNA clone was isolated from a cDNA library [2].
• A 366-bp cDNA fragment was initially obtained from the B race utilizing a reverse transcription/polymerase chain reaction and degenerate primers based on conserved amino acid sequences found in all SS enzymes [2].
• Comparison of the TSS deduced amino acid sequence with currently described SS from different species showed the highest identify with Nicotiana benthamiana (97%), followed by Glycyrrhiza glabra (81%), Arabidopsis thaliana (74%), rat (40%), and yeast (37%) [4].

Biological context of SQS1

• Squalene synthase activity was found in the cell-free extracts of Escherichia coli transformed with the recombinant plasmids for GgSQS1 and GgSQS2, respectively [5].
• Dominance of a resistance trait can be defined as a measure of the relative position of the phenotype of the heterozygote RS compared with the phenotype of the two corresponding homozygotes, SS and RR [6].

Associations of SQS1 with chemical compounds

• Cloning and characterization of the Arabidopsis thaliana SQS1 gene encoding squalene synthase--involvement of the C-terminal region of the enzyme in the channeling of squalene through the sterol pathway [7].
• However, a chimeric SQS resulting from the replacement of the 66 C-terminal residues of the Arabidopsis enzyme by the 111 C-terminal residues of the Schizosaccharomyces pombe enzyme was able to confer ergosterol prototrophy to strain 5302 [7].

Enzymatic interactions of SQS1

• Squalene synthase (SQS) catalyzes the first committed step of the sterol biosynthetic pathway [7].

Other interactions of SQS1

• SQS1 and SQS2 have an identical organization with regard to intron positions and exon sizes and encode SQS isoforms showing a high level of sequence conservation (79% identity and 88% similarity) [7].
• Two cDNAs (GgSQS1 and GgSQS2) encoding squalene synthase have been isolated from licorice, Glycyrrhiza glabra L., and characterized [5].

Analytical, diagnostic and therapeutic context of SQS1

• Southern blot hybridization indicated only two copies of the SS gene in the tobacco genome [4].

References