A "PAN gene" isn't a standard term you'll find widely used. However, considering the context of pan-genomes, it refers to a gene found within the dispensable genome of a species. The pan-genome represents the entire genetic repertoire of a species.
To fully understand, let's break it down:
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Pan-Genome: According to the reference, the pan-genome is the entire set of genes within a species. (10-Feb-2021)
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Core Genome: The pan-genome includes a core genome, which consists of genes present in all individuals of the species. (10-Feb-2021)
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Dispensable Genome (or Shell Genome): This is the variable part of the pan-genome. It contains genes present in some but not all individuals of the species. These genes contribute to diversity and adaptation. A PAN gene, therefore, belongs to this category. (10-Feb-2021)
Key Characteristics of PAN Genes:
- Variable Presence: They aren't found in every individual of a species.
- Adaptation: They often contribute to species adaptation to different environments or lifestyles.
- Horizontal Gene Transfer: They're frequently acquired through horizontal gene transfer (HGT).
- Functional Diversity: They can encode functions like antibiotic resistance, virulence factors, or metabolic capabilities not found in all members of the species.
Example Scenario:
Imagine a bacterial species. All individuals share genes for basic survival functions like DNA replication and protein synthesis (the core genome). However, some individuals have genes that confer resistance to a specific antibiotic. These antibiotic resistance genes would be considered PAN genes, as they are part of the dispensable genome.
In Summary
While "PAN gene" is not a formal term, in the context of pan-genomics, it signifies a gene belonging to the dispensable genome - a gene that isn't universally present in all members of a species, contributing to its diversity and adaptability.
