E. coli protein troika discovered to be essential to survival

Scientists in Canada, the UK and the US have for the first time found a link between three proteins in Escherichia coli (E. coli) that are necessary for the bacterium's survival. Because one of the genes is also present in the human genome, the findings have implications for the study of essential processes in humans as well. The study was published in the Journal of Bacteriology.

"Although the nature and exact number of essential genes is likely to vary between bacterial species," the study reads, "it is becoming clear that there is a core set of genes that are essential for the viability of probably most bacteria."

The researchers looked into the significance of three 'conserved' genes in the E. coli genome: yjeE, yeaZ and ygjD, which have been present in the bacterium throughout its evolution. Using a combination of genetic and biochemical approaches to study the protein products of these genes (YjeE, YeaZ, and YgjD), they found that the three proteins in fact form an 'interaction network', and are involved in the same essential cellular process.

"The exact functions of the three key cellular proteins we have studied here have so far been enigmatic," the study reads. "However, it is clear that the loss of any of these three proteins results in startling changes to the morphology of E. coli."

Furthermore, the study revealed that "that the major, if not only roles, of YjeE and YeaZ are to regulate the activity of YgjD". Their observations revealed that YeaZ acts specifically to break down YgjD, and indicate that "one of the main functions of YjeE is to control or regulate the interaction between YeaZ and YgjD".

The ygjD gene has also been observed in the genomes of life forms other than bacteria, including humans. The pivotal role the gene plays in the survival of E. coli has directed attention to its potential role in human development.

"Finding out that these genes are essential in E. coli and also appear in the genomes of other species tells us that they are very important indeed," said Tracy Palmer of the University of Dundee in the UK. "In the case of one of the genes, it is also found in the human genome, which makes it especially interesting. The mystery remains as to what they actually do; but whatever it is, it must be really crucial."

The results of some of the experiments carried out in the study indicated that yjeE, yeaZ and ygjD affect how E. coli cells respond to different messages that tell them when to divide, said Professor Palmer. "If they do the same thing in humans, then any problems with these genes could easily lead to developmental abnormalities or cancer," she explained.

The results of the study also help to explain why these three proteins are encoded in the genomes of almost all bacteria and why they are all critical for growth, since they all interact in the same cellular pathway. Future studies, the authors hope, will provide further insights into the specific cellular processes controlled by the three proteins.

"This work is a good example of where having a genome sequence opens up many possible avenues of enquiry," remarked Douglas Kell of the UK's Biotechnology and Biological Sciences Research Council, which provided funding for the study. "It also makes clear the value of an organised approach to accessing and using genome information. Research focused on maximising the use of genome sequences will surely, therefore, accelerate discovery of information that is of social and economic importance."

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