A new pathogen has been discovered. After sequentially deleting each of the orga

Question

A new pathogen has been discovered. After sequentially deleting each of the organism’s genes, researchers identify a gene, that when expressed, results in the production of a protein whose absorbance is shifted from 280nm to 270nm.

If the pathogenic protein is run over a gel filtration column under denaturing conditions, two peaks are observed. One peak corresponds to the expected molecular weight of the protein while the second peak is very small.

When this pathogenic protein is purified from the pathogen and added to in vitro eukaryotic translation reactions, efficiency of translation decreases. When this pathogenic protein is recombinantly expressed and purified from E.coli and added to in vitro eukaryotic translation reactions, efficiency of translation is unaltered.

a) Hypothesize how the pathogenic protein is functioning. Draw a cartoon. State clearly what the pathogenic protein does in human cells

b) Describe an experiment that would support your hypothesis. State what the results would be if your hypothesis is correct.

Explanation / Answer

A)     absorbance (A) = -log( percent transmittance/100) and ,

        percent transmittance = (amount of light transmitted through solution /amount of light transmitted through    solvent)

        Since the absorbance of protein decreases,transmittance increases and hence concentration decreases (beer's law)

        Therefore we can safely conclude that subsequent removal of genes has changed the absorbance of the protein. Hence the true protein is a translation product from not just a single gene as mentioned in the question.

Hypothesis: since the protein shows two observable peeks (one of which does not correspond to the protein), it is safe to predict that the translational product is adulterated. This can also be deciphered from the fact that when translated product is introduced into eukaryotes there is a negative adverse effect (slows the process of protein translation from m-RNA).When first introduced into e.coli the the adulterated byproduct is removed (attaches to the E.coli m-RNA and slows down subsequent translation) from the translated protein, this protein when introduced in humans causes no adverse effect due to the absence of m-RNA binding protein byproduct.

B)     experiment and expected results: gel filtration column showed two peeks (one of the protein and other of the adulterant).Subsequent gel filtration after retrieval from e.coli will only have a single peek due to the absence of the adulterant.

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