Question

DNA Polymerase Holoenzyme Has Three Subcomplexes

The E. coli replicase DNA polymerase III is a 900-kD complex with a ____ structure.

Each monomeric unit has:
a __ ___ (alpha, epsilon, theta)
a ____ subunit (tau)
a ____ component = clamp (beta)

Answer 1

DNA Polymerase III in E. coli is a multicomponent enzyme with a complex structure, consisting of multiple subunits including the core enzyme subunits (alpha, epsilon, theta), the tau subunit, and the beta clamp.

Step-by-step explanation:

DNA Polymerase III Holoenzyme Structure

The E. coli replicase DNA polymerase III is a 900-kD complex with a multisubunit structure. Each monomeric unit of the DNA polymerase III holoenzyme consists of multiple subcomplexes that play different roles in DNA replication. The core of the enzyme includes the alpha (α) subunit which is responsible for the polymerization activity, the epsilon (ε) subunit which has the proofreading function due to its 3'→5' exonuclease activity, and the theta (θ) for assembling the polymerase on the DNA.

Additionally, the tau (τ) subunit is critical for the enzyme's function as it holds the complex together and helps in the dimerization of the polymerase core. Lastly, the beta clamp (β) component enables the polymerase to slide along the DNA molecule without dissociating, which increases the processivity of the enzyme during DNA replication.

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