MICRB 412 3.20

Introduction to Genetic Engineering and Technology

• Bacteria have made significant advancements in genetic engineering.

• Full genetic blueprints are now available, enabling precise manipulations.

• Recognizing mutations that lead to genetic diseases, such as sickle cell anemia, is essential for corrective measures.

Basics of DNA Repair

• DNA can self-repair when broken; enzymes facilitate this process.

• Incomplete resealing of DNA can lead to deletions or exchanges between chromosome segments during mitosis.

Bacterial Defense Mechanisms

• Bacteria defend themselves against viral infections (e.g., bacteriophages) by utilizing sequences in their DNA that can recognize and cleave foreign DNA.

• This mechanism opened doors for scientists to engineer systems that can cut DNA at specific sites.

Engineered Nucleases

• Zinc Finger Nucleases (ZFNs):

  • Designed to cut DNA at specific locations.

  • Composed of zinc finger motifs that recognize specific triplet codon sequences.

  • Can recognize large DNA sequences (up to 18 base pairs) for increased specificity.

  • Despite their utility, production is complicated and costly.

• Transcription Activator-Like Effector Nucleases (TALENS):

  • Another class of engineered nucleases that are derived from natural systems.

  • Recognize nucleotides with a smaller protein repeat system, providing diverse options for targeting.

Discovery of CRISPR Technology

• CRISPR systems were identified through the analysis of bacterial genomes, revealing unique patterns suggesting an adaptive immune mechanism.

• Three key steps of bacterial immunity via CRISPR:

  1. Acquisition: Bacteria cleave invasive DNA and integrate pieces into a CRISPR array for future defense.

  2. Processing: Generating short RNA segments that correspond to the inserted foreign DNA.

  3. Interference: The system recognizes and binds to the foreign DNA upon reinfection to cleave it.

Benefits and Advances in CRISPR

• CRISPR is inexpensive, eliminating concerns associated with protein purification and misfolding.

• Capable of delivering various proteins and genetic instructions to specific locations within a cell.

• This technology enables regulation of gene expression, visualization of genetic sequences (e.g., through fluorescent markers), and potential treatment for genetic disorders.

• Revolutionizes drug development and genetic research, making tools accessible to a broader scientific community.

Potential Applications of CRISPR

• Altering mosquitos to prevent malaria transmission by targeting specific genes, thereby affecting their ability to carry pathogens.

• Exploring applications for genetically engineering fungi and insects to combat agricultural pest threats.

• The potential for personalized medicine, specifically developing targeted treatments based on individual genetic information.

Conclusion

• Genetic engineering through bacteria-derived systems has transformed the field with tools like ZFNs, TALENS, and CRISPR, leading to revolutionary breakthroughs in biotechnology, medicine, and agriculture.

• Essential to continue exploring and addressing challenges associated with gene targeting and therapeutic applications in humans.