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Why do introns in eukaryotic genes create challenges for bacterial protein production?

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DNA extraction and recombinant DNA technology — recombinant DNA The process of DNA extraction is necessary to isolate molecules of DNA from cells or tissues. A series of steps, including the use of protease enzymes to strip proteins from the DNA, are required for isolating pure DNA that is suitable for use in later procedures, such as cloning or sequencing.

In eukaryotic genes, coding sequences are often interrupted by noncoding regions known as introns, which must be removed through a complex process called RNA splicing before the messenger RNA can be translated into protein.

Bacterial cells, which are prokaryotes, lack the specialized enzymatic machinery—specifically the spliceosome—required to remove these introns. Consequently, if a eukaryotic gene containing introns is introduced into a bacterium, the cell cannot process the genetic information correctly, preventing the production of the intended functional protein.1

To overcome this challenge in recombinant DNA technology, scientists often use cDNA (complementary DNA). Because cDNA is synthesized from mature mRNA that has already been spliced to remove introns, it provides a continuous coding sequence that bacteria can successfully translate into protein.1