Molecular Toxinology – Cloning Toxin Genes for Addressing Functional Analysis and Disclosure Drug Leads

Abstract

The revolution in Biology started earlier with the genetic works of Gregor Mendel (1866), who, through his work with pea breeding, observed the phenomena of dominance and segregation of traits and discovered several laws of heredity. The pioneered endeavor of deciphering the linkage between transmission of heredity and a biomolecule was succeeded by the works of Griffith (1928), Oswald Avery, Colin McLeod, and Marylin McCarty (1944), who demonstrated that the instruction for virulence traits in bacteria was contained in the deoxyribonucleic acid (DNA) molecule, as well as Alfred Hershey and Martha Chase (1952), who elegantly proved that the progeny of bacteriophage is propagated after the injection of the bacteriophage’s genetic material into the host cell. The hallmark of molecular biology arose in 1953 with the description of the double-helix backbone of DNA by James Watson and Francis Crick, who also described that such a structure may suggest a mechanism of DNA replication (Watson and Crick, 1953). Notably, the deduction of the DNA structure was based on the data of other works by Erwin Chargaff, who determined the base correspondence and ratios in nucleic acid, and by Rosalind Franklin, who obtained DNA fiber images from X-ray diffraction. The elegant genetic experiments from Francois Jacob and Jacques Monod (1961) established the concept of cis-acting elements and the mechanism by which the operator and repressor regulate β-galactosidase expression in Escherichia coli and sugar metabolism (Jacob and Monod, 1961). At same time, Marshal Nirenberg was leading the race to decipher the genetic code (Nirenberg, 2004). By the 1970s, Fred Sanger and Walter Gilbert developed two distinct methodologies for DNA sequencing, which culminated with automated high-throughput DNA sequence analysis, thus opening the door for the genomic revolution and the publication of hundred of genomes, including the human genome. The central dogma of molecular biology, which postulated that DNA directs its own replication and its transcription to yield RNA, which in turn directs its translation to form protein, was wisely proposed by F. Crick in 1958 (Crick, 1970). This also included the “probable transference of information”, which we know now as RNA replication and reverse transcription, after the seminal works of D. Baltimore (1970) and J.M. Bishop on the molecular virology of retroviruses and oncogenes (1973). The ‘biological revolution’ continued forward with important discoveries such as the mechanism by which chromosomes are protected at their ends (the telomeres) against degradation and the