Occurrence and characterization of PEND proteins in angiosperms

Area of Science:

• Plant molecular biology
• Chloroplast biology
• Genetics

Background:

• The PEND protein is a DNA-binding protein located in the inner chloroplast envelope membrane.
• It possesses a DNA-binding domain (cbZIP), a repeat domain, and a transmembrane domain.
• PEND homologs are present in various angiosperms, with lower sequence conservation in monocots.

Purpose of the Study:

• To investigate the presence and localization of PEND protein homologs in angiosperms.
• To determine the functional analogy of PEND homologs in crucifers compared to pea PEND protein.
• To explore the evolutionary distribution of PEND-related sequences.

Main Methods:

• Localization studies using Green Fluorescent Protein (GFP) fusions of PEND homologs in *Arabidopsis thaliana* and *Brassica napus*.
• Targeting GFP-fusions to chloroplasts to observe subcellular localization.
• Immunoblot analysis to assess the presence and potential dimerization of crucifer PEND homologs.

Main Results:

• PEND homologs were successfully targeted to chloroplasts in *A. thaliana* and *B. napus*, localizing to nucleoids and chloroplast periphery, respectively.
• Immunoblot analysis indicated that crucifer PEND homologs likely exist as dimers in chloroplasts, similar to pea.
• PEND-related sequences were identified in angiosperms but not in non-flowering plants or algae.

Conclusions:

• The PEND protein is conserved in angiosperms, particularly in crucifers.
• Crucifer PEND homologs appear functionally analogous to the pea PEND protein.
• The study provides insights into the distribution and potential function of PEND proteins in plant chloroplasts.