Zainab M. Almutairi, Monther T. Sadder
Abstract
The decision to replicate its DNA is of crucial importance for every cell and, in many organisms, is decisive for the progression through the entire cell cycle. DNA polymerases are required to maintain the integrity of genome during DNA replication. DNA Polymerase Alpha (POLα) encodes the putative catalytic subunit of the DNA polymerase α which plays an essential role in the initiation of DNA replication. Here, we present the cloning, characterization and expression of a putative SlPOLα gene in tomato by isolating cDNA clones corresponding to SlPOLα gene from tomato using primers designed from available ESTs based on conserved sequences between PcG genes in Arabidopsis thaliana and tomato. The SlPOLα cDNAs were cloned into pBS plasmid and sequenced. Both 5' and 3' RACE were generated and sequenced. The flcDNA for SlPOLα gene length was composed of 4,944 bp, containing 103 bp in the 5'UTR; 4,683 bp in the ORF; and 158 bp in 3'UTR. The translated ORF encodes a polypeptide of 1,561amino acids. Alignment of deduced amino acids indicated that there are highly conserved regions between tomato SlPOLα predicted protein and hypothetical plant POLα gene family members. Both unrooted phylogenetic trees, constructed using maximum parsimony and maximum likelihood methods indicated that there is a close relationship between SlPOLα predicted protein and POLα protein of Mimulus guttatus. SlPOLα was strongly expressed in proliferating tissues (closed floral buds) and moderately expressed in flower tissues, whereas, it was weakly expressed in non-proliferating tissues (unripe fruit).
Keywords: Tomato, DNA polα gene, flcDNA, phylogenetics.
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