Inhibitors of ethylene synthesis

IN CASE OF TOMATOES:

pTOM5 encodes for phytoene synthase which promote  lycopene synthesis that gives red coloration

pTOM6 gene encodes for polygalacturonase. This enzyme  degrades the cell wall, resulting in fruit softening.

pTOM gene encodes for ACC oxidase. This enzyme  catalyzes the ethylene formation that triggers the fruit ripening.

Calgene introduced a gene in plant which synthesize a  complementary mRNA to PG gene and inhibiting the  synthesis of PG enzyme.

On May 21, 1994, the genetically engineered Flavr Savr tomato was introduced.

TLS Online TPP Program

#Id: 7076

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 7077

#Unit 3. Fundamental Processes

ThrRS has the opposite problem: It must synthesize Thr–tRNAThr but not Val–tRNAThr. Specificity is conferred by the aminoacylation site, which contains a Zn2+ ion that is coordinated by the side chain OH group of threonine. Valine cannot coordinate the Zn2+ in this way and hence does not undergo adenylylation by ThrRS.  A separate editing site deals with misacylated Ser–tRNAThr. TyrRS distinguishes between tyrosine and phenylalanine through hydrogen missing from the repertoire are GlnRS and asparaginyl-tRNA synthetase (AsnRS). To synthesize Gln-tRNAGln and Asn-tRNAAsn, these organisms possess distinct glutamyl-tRNA synthetase (GluRS) and aspartyl-tRNA synthetase (AspRS) enzymes that are nondiscriminating (ND). GluRSND synthesizes both Glu-tRNAGlu as well as misacylated Glu-tRNAGln; AspRSND synthesizes both Asp-tRNAAsp and misacylated Asp-tRNAAsn.

TLS Online TPP Program

#Id: 7078

#Unit 3. Fundamental Processes

Selenocysteine is generated enzymatically from serine carried on a special tRNA that is charged by serine-tRNA synthetase. The Sec residues of selenoproteins are thought to participate in redox reactions such as those catalyzed by mammalian glutathione peroxidase and thioredoxin reductase

TLS Online TPP Program

#Id: 7079

#Unit 3. Fundamental Processes

Selenocysteine, sometimes called the “twenty-first amino acid,”

is incorporated into proteins with the aid of a tRNA that interprets the UGA Stop codon as a Sec codon. tRNASec is initially charged with serine in a reaction catalyzed by the same SerRS that charges tRNASer.

TLS Online TPP Program

#Id: 7080

#Unit 3. Fundamental Processes

A dedicated protein (a special elongation factor) named SELB in complex with GTP is required to deliver Sec–tRNASec to the ribosome. SELB ∙ GTP ∙ Sec–tRNASec reads the UGA codon as Sec rather than “Stop,” provided that the ribosomally bound

mRNA has a hairpin loop on the 3′ side of the UGA specifying Sec.

TLS Online TPP Program

#Id: 7081

#Unit 3. Fundamental Processes

The tRNAAla structural elements recognized by then Ala-tRNA synthetase are unusually simple.  A single G=U base pair 3:70 is the only element needed for specific binding and aminoacylation