Poly(A) RNA polymerase PAPD7 (PAPD7)

Poly(A) RNA polymerase PAPD7 is a noncanonical poly(A) polymerase enzyme that catalyzes the addition of oligoadenylate tails to the 3′ ends of specific RNAs, including viral RNAs and noncoding RNAs[1][2]. Unlike canonical poly(A) polymerases, PAPD7 does not require a canonical poly(A) signal for activity and often acts as part of a complex that recognizes specific RNA elements, such as the hepatitis B virus (HBV) post-transcriptional regulatory element (PRE)[1][2]. PAPD7, together with its paralog PAPD5, plays a crucial role in stabilizing HBV RNA, making it a promising antiviral target for therapeutic intervention in hepatitis B[2]. Small-molecule inhibitors of PAPD7 (and PAPD5) disrupt viral RNA integrity, leading to decreased production of viral proteins. PAPD7 is mainly localized in the cytoplasm and is functionally less sensitive to inhibition than its paralog PAPD5[1]. There is ongoing research to evaluate PAPD7 inhibitors for antiviral therapy, but clinical safety and efficacy remain to be determined.

Other names

Noncanonical poly(A) polymerase PAPD7Terminal nucleotidyltransferase 4B (TENT4B; is sometimes used)hTRF4-2 (in some older literature, not common)

Inhibition of PAPD7 by small molecules (e.g., AB-452, RG7834) blocks stabilization of hepatitis B virus RNA by interfering with poly(A) tail formation, thereby promoting RNA degradation and reducing viral protein/mRNA production[1][2].