Final answer:
The tau (τ) subunit tethers two DNA polymerase III molecules together in theta replication to form a functional dimer, crucial for efficient DNA synthesis.
Step-by-step explanation:
In theta replication, the τ (tau) subunit tethers two DNA polymerase III enzymes together to create a functional dimer. This tau subunit is crucial for the polymerase's activity during the replication of DNA. In prokaryotes, DNA polymerase III is a complex enzyme composed of several polypeptide subunits which include alpha (α), epsilon (ε), theta (θ), and tau (τ) among others. The core enzyme consists of these subunits minus the τ subunit.
However, the τ subunit has a special role in the replication process as it holds the DNA polymerase III enzymes in the correct configuration for efficient DNA synthesis. This formation allows the DNA polymerase III to replicate the leading and lagging strands of DNA simultaneously during cell division.