PAP8/pTAC6 Is Part of a Nuclear Protein Complex and Displays RNA Recognition Motifs of Viral Origin

International Journal of Molecular Sciences

David Cobessi¹  François-Xavier Gillet²  Louise Chambon²  Thomas Pfannschmidt²  Maha Chieb²  Robert Blanvillain² 

[1] CNRS, CEA, IBS, University Grenoble Alpes, F-38000 Grenoble, France;CNRS, CEA, INRA, IRIG-LPCV, University Grenoble-Alpes, F-38000 Grenoble, France;

关键词: Arabidopsis;    PAP8/pTAC6;    PEP/PAPs;    chloroplast;    biogenesis;    RNA recognition motif;   

DOI  :  10.3390/ijms23063059

来源: DOAJ

【 摘 要 】

Chloroplast biogenesis depends on a complex transcriptional program involving coordinated expression of plastid and nuclear genes. In particular, photosynthesis-associated plastid genes are expressed by the plastid-encoded polymerase (PEP) that undergoes a structural rearrangement during chloroplast formation. The prokaryotic-type core enzyme is rebuilt into a larger complex by the addition of nuclear-encoded PEP-associated proteins (PAP1 to PAP12). Among the PAPs, some have been detected in the nucleus (PAP5 and PAP8), where they could serve a nuclear function required for efficient chloroplast biogenesis. Here, we detected PAP8 in a large nuclear subcomplex that may include other subunits of the plastid-encoded RNA polymerase. We have made use of PAP8 recombinant proteins in Arabidopsis thaliana to decouple its nucleus- and chloroplast-associated functions and found hypomorphic mutants pointing at essential amino acids. While the origin of the PAP8 gene remained elusive, we have found in its sequence a micro-homologous domain located within a large structural homology with a rhinoviral RNA-dependent RNA polymerase, highlighting potential RNA recognition motifs in PAP8. PAP8 in vitro RNA binding activity suggests that this domain is functional. Hence, we propose that the acquisition of PAPs may have occurred during evolution by different routes, including lateral gene transfer.

【 授权许可】

Unknown