Tetracycline has only limited use in treatment because resistance has risen in d

Question

Tetracycline has only limited use in treatment because resistance has risen in different groups of bacteria. One mode of resistance is the acquisition of a gene (tetO) by transfer between bacteria. The gene encodes a ribosomal protection protein (RPP). RPPs are similar in sequence to EF-G and EF-Tu.

1) Why would sequence similarity to elongation factors be a benefit in conferring tetracycline resistance?

2) If RPP was exactly like an elongation factor then it would be blocked from entering the ribosome, just like the EFs. Describe an additional potential feature of an RPP that would not be a feature of EFs.

Explanation / Answer

Tetracycline is a broad spectrum antibitic which inhibit the bacterial growth by binding with ribosomes of microorganisms. Upon binding with ribosomes, tetracycline block the binding of elongation factor to the ribosomes which result in inhibition of addition of amino acids into growing peptide chain during elongation phase of translation and thus inhibit protein synthesis leading to inhibition of microbial growth.

1. The RPP (ribosome protection proteins) produced by bacterial gene prevent the binding of tetracycline to the ribosomes and thus a resistance to the tetracycline develops. The similarity of sequence of RPP with elongation factor G and Tu is a benefit in conferring tetracycline resistance because it will block the tetrcycline to bind with ribosomes and also act as elongation factor and thus there is no need to bind elongation factor with ribosomes and thus protein synthesis occurs even when elongation factor is not bind to ribosomes.

2. RPP has sequence similarity to the elongation facors, but not exactly same as elongation factor which allow binding of RPP with ribosomes even in the presence of tetracycline. The differences between RPP and elongation factors allow the RPP to bind with ribosomes and do not allow the binding of elongation factors in the presence of tetracycline.

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