Molecular characterization of the PEND protein, a novel bZIP protein present in the envelope membrane that is the site of nucleoid replication in developing plastids.
Plastid nucleoids are known to bind to the envelope membrane in developing chloroplasts. Here, plastid DNA is extensively replicated. We previously detected a DNA binding protein in the inner envelope membranes of developing plastids in pea and named it PEND (for plastid envelope DNA binding) protein. In this study, we report on the structure and molecular characterization of a cDNA for the PEND protein. As a result of screening cDNA libraries in lambdagt11 with one of the target sequences of the PEND protein as a probe, we obtained a clone (PD2) for a novel DNA binding protein consisting of 633 amino acid residues. Analysis of the N-terminal sequence of the purified PEND protein indicated that the transit peptide is just 16 residues long. The PEND protein was detected specifically in the plastid envelope membrane of young unopened leaf buds by immunoblot analysis. The PEND protein consists of a basic region plus zipper region, an unprecedented sextuple repeat region, and a putative membrane-spanning region. The basic region with a zipper region seems to have diverged from that of other plant transcription factors. In addition, the PEND protein could be a distant homolog of the trans-Golgi network integral membrane proteins. The PEND protein is therefore a novel type of DNA binding protein that binds to the membrane as an intrinsic membrane protein.
Sato
N
N
Department of Biochemistry and Molecular Biology, Faculty of Science, Saitama University, Urawa 338, Japan. naokisat@molbiol.saitama-u.ac.jp
Ohshima
K
K
Watanabe
A
A
Ohta
N
N
Nishiyama
Y
Y
Joyard
J
J
Douce
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D050976:Basic-Leucine Zipper Transcription Factors; D001665:Binding Sites; D002417:Cattle; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004261:DNA Replication; D018076:DNA, Complementary; D018744:DNA, Plant / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism*; D016350:Leucine Zippers; D008969:Molecular Sequence Data; D018532:Pisum sativum / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010940:Plant Proteins; D018087:Plastids / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D050976:Basic-Leucine Zipper Transcription Factors; D018076:DNA, Complementary; D018744:DNA, Plant; D004268:DNA-Binding Proteins; C112640:PEND protein, plant; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins