Crescentus: A Genetic Analysis

In order to survive in and withstand many environmental pressures, one aspect that is both critical and necessary is the ability for organisms to be able to regulate gene expression. Amongst bacterial species, one gene that has been identified as a main factor is the cell-cycle transcriptional regulator, known as ctrA. It controls at least 25% of the genes involved in the cell cycle process (Mercer et al., 2010). ctrA has been highly studied in the model organism, Caulobacter crescentus, in which it is responsible for controlling various functions during the cell cycle by activating or repressing gene expression of approximately 25% of the 553 cell cycle-regulated genes in the genome (Reisenaur et al., 1999). This protein also blocks initiation of DNA replication by binding to five sites within the chromosomal origin (Brilli et al.,2010). During the G1 phase when C. crescentus transitions from swarmer cells to stalked cells, ctrA suppresses replication in the swarmer …show more content…
crescentus is just one bacteria belonging to an extremely diverse phylum known as Proteobacteria. Not only has the ctrA gene been found to be essential in C. crescentus, it has also been found quite necessary for viability in three other bacterium: Sinorhizobium meliloti, Agrobacterium tumefaciens, and Brucella abortus (Greene et al.,2012). In addition to the three bacterium previously stated, research has also supported that ctrA plays a critical role in the regulation of motility amongst Rhodobacter capsulatus, Rhodospirillum centenum, and Silicibacter sp. TM1040 (Greene et al.,2012). Also members of the genus Rhodobacter and of the phylum Proteobacteria, Rhodobacter sphaeroides 2.4.1. and Rhodobacter sphaeroides 17029 were observed in the lab for the presence of the ctrA gene, in addition to the bacteria Escherichia coli DH5α and Rhodopseudomonas palustris BisB5. With all four bacteria being members of Proteobacteria, they can either strongly support or disapprove of the hypotheses being