A study was conducted in an attempt to determine which functional regions of a particular conjugative transfer gene (tra1) are involved in the transfer of plasmid R27 in Salmonella enterica. The R27 plasmid is of significant clinical interest because it is capable of encoding multiple-antibiotic resistance to typhoid fever. To identify functional regions responsible for conjugal transfer, an analysis by Lawley et al. [(2002). J. Bacteriol. 184:2173–2180] was conducted in which particular regions of the tra1 gene were mutated and tested for their impact on conjugation. Shown here is a map of the regions tested and believed to be involved in conjugative transfer of the plasmid. Similar coloring indicates related function. Numbers correspond to each functional region subjected to mutation analysis. Accompanying the map is a table showing the effects of these mutations on R27 conjugation. Effects of Mutations in Functional Regions of Transfer Region 1 (tra1) on R27 Conjugation R27 Mutation in Conjugative Relative Conjugation Region Transfer Frequency (%) 1 + 100 2 + 100 3 - 0 4 + 100 5 - 0 6 - 0 7 + 12 8 - 0 9 - 0 10 - 0 11 + 13 12 - 0 13 - 0 14 - 0 Given the data, do all functional regions appear to influence conjugative transfer?

Key Concepts

Conjugative Transfer

Conjugative transfer is a process by which one bacterium transfers genetic material to another through direct contact, often mediated by plasmids. This mechanism is crucial for the spread of antibiotic resistance among bacteria, as plasmids can carry genes that confer resistance. Understanding the functional regions of genes involved in this process, such as tra1, is essential for determining how effectively plasmids can be transferred.

Gene Mutation Analysis

Gene mutation analysis involves systematically altering specific regions of a gene to observe the effects on its function. In the context of the tra1 gene, mutations were introduced to identify which regions are critical for conjugative transfer. By comparing the conjugation frequencies before and after mutations, researchers can infer the importance of each region in the gene's overall function.

Functional Regions of Genes

Functional regions of genes refer to specific segments that play distinct roles in the gene's activity, such as encoding proteins or regulatory elements. In the study of the tra1 gene, different regions were tested to determine their contribution to plasmid transfer. The results indicated that not all regions influence conjugative transfer, as some mutations resulted in a complete loss of function, while others maintained or reduced activity.