AtDeg2 – a chloroplast protein with dual protease/chaperone activity

Abstract

Chloroplast protease AtDeg2 (an ATP-independent serine endopeptidase) is cytosolically synthesized as a precursor, which is imported into the chloroplast stroma and deprived of its transit peptide. Then the mature protein undergoes routing to its functional location at the stromal side of thylakoid membrane. In its linear structure AtDeg2 molecule contains the protease domain with catalytic triad (HDS) and two PDZ domains (PDZ1 and PDZ2). In vivo AtDeg2 most probably exists as a supposedly inactive haxamer, which may change its oligomeric stage to form active 12-mer, or 24-mer. AtDeg2 has recently been demonstrated to exhibit dual protease/chaperone function. This review is focused on the current awareness with regard to AtDeg2 structure and functional significance.

Chloroplast protease/chaperone AtDeg2 influences cotyledons opening and reproductive development in Arabidopsis

“…Furthermore, AtDeg2 is involved in chloroplast senescence program, since 4-week-old deg2 mutants did not display senescence-related undulations of chloroplast envelope and thylakoids and had less plastoglobules per chloroplast cross section compared to WT plants [9]. In addition, highly conserved cis-regulatory elements specific for transcription factors engaged in leaf senescence and carotenogenesis have been identified in the AtDEG2 promoter [10]. However, no comprehensive studies of the role of AtDeg2 in A. thaliana plant growth and development have been reported and no efforts were undertaken to discriminate between individual roles of protease and chaperone activities of AtDeg2 in controlling chronological progression of stages in plant ontogenesis.…”