Isolation and partial characterization of an unidentified cDNA clone from Arabidopsis thaliana

Abstract
With advances in biotechnology and easy access to large data banks, it is possibile to use random cDNA sequences to analyze and identify genes that encode for the function of proteins in many species. The Arabidopsis Genome Project provides for the comparison of deduced nucleotide and amino acid sequences of many clones to previously characterized genes and proteins. Plasmid DNA was isolated and sequenced to study an unknown cDNA clone that was obtained from Arabidopsis thaliana. From our partial sequence, this anonymous cDNA clone 92K11T7 was homologous to GenBank accession number T20778. Using the Mac Vector program, the translated amino acid sequence of the longest open reading frames was determined from reading the automated sequence [5]. However, these results when entered into the BLAST search and Arabidopsis thaliana EST programs did not provide good homologies in DNA/protein sequence data bases [1,7]. Hydropathy analysis and protein secondary structure was also performed to reveal the nature of our unnamed protein [5]. The closest homology search to our cDNA sequence had a score above 150 and a low P value, but there was no identifiable name of the protein in the searches. Digestion of genomic DNA with selected restriction enzymes in Southern hybridization indicated several related genes within a gene family or between related species. Northern experiments showed gene expression for our protein in only the wounded Arabidopsis tissue and not in any of the normal whole, leaf, flower, or stem tissues. Thus, further experimentation and analyses will have to be performed to give better insight into the properties and characterization of the unidentified protein.