Catalyzes the transfer of endogenously produced octanoic acid from octanoyl-acyl-carrier-protein onto the lipoyl domains of lipoate-dependent enzymes. Lipoyl-ACP can also act as a substrate although octanoyl-ACP is likely to be the physiological substrate (By similarity) (PubMed:11602263). Together with LIP1P is essential for de novo plastidial protein lipoylation during seed development. Acts redundantly with LIP2P2 (PubMed:23581459). L-lysyl-[protein] + octanoyl-[ACP] = H(+) + holo-[ACP] + N(6)-octanoyl-L-lysyl-[protein] Protein modification; protein lipoylation via endogenous pathway; protein N(6)-(lipoyl)lysine from octanoyl-[acyl-carrier-protein]: step 1/2. Expressed in roots, leaves and flowers (PubMed:11602263, PubMed:23581459). Expressed in cauline leaves, stems and siliques (PubMed:23581459). No visible phenotype under normal growth conditions, but the double mutants lip2p and lip2p2 are embryonic lethal. In the reaction, the free carboxyl group of octanoic acid is attached via an amide linkage to the epsilon-amino group of a specific lysine residue of lipoyl domains of lipoate-dependent enzymes. Belongs to the LipB family. The predicted gene At4g31060 has been split into 2 genes: At4g31060 and At4g31050. The predicted gene At4g31060 has been split into 2 genes: At4g31060 and At4g31050.