Characterization of two genes, Sig1 and Sig2, encoding distinct plastid σ factors in the moss Physcomitrella patens: phylogenetic relationships to plastid σ factors in higher plants

• Published in: FEBS letters Vol. 499; no. 1; pp. 87 - 91
• Main Authors: Hara, Keishi, Morita, Masakatsu, Takahashi, Rieko, Sugita, Mamoru, Kato, Seiji, Aoki, Setsuyuki
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 15.06.2001
• Subjects: Amino Acid Sequence; Arabidopsis - genetics; Arabidopsis Proteins; Bryopsida - cytology; Bryopsida - genetics; Gene Expression Regulation, Plant - radiation effects; Genes, Plant - genetics; Genes, Reporter - genetics; Light; Molecular Sequence Data; Multigene Family - genetics; Phylogeny; Physcomitrella patens; Plant Proteins - chemistry; Plant Proteins - genetics; Plastid; Plastids - genetics; Protein Transport; Recombinant Fusion Proteins - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA, Plant - genetics; RNA, Plant - metabolism; Sequence Alignment; Sigma Factor - chemistry; Sigma Factor - genetics; Sigma Factor - metabolism; Transcription; σ Factor; σ Factor; Plastid; Transcription; Physcomitrella patens
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/S0014-5793(01)02530-3

We isolated the cDNA for a σ factor from the moss Physcomitrella patens, which possesses unusually large N-terminal extension and the conserved subdomains 1.2–4.2. Phylogenetic analyses indicated that this novel σ factor and PpSIG1* 2 2 To avoid confusion, here we refer to the σ factor gene and its protein product previously identified in Physcomitrella by our group ([Hara, K. et al. (2001) Biochim. Biophys. Acta 1517, 302–306]; AB046872) as sig1* and PpSIG1*, respectively; otherwise new names ( Sig2 and PpSIG2, respectively) are used. , a plastid σ factor previously identified from Physcomitrella, were classified into SigA and SigB groups, two major classes of higher plant plastid σ factors, respectively. According to the nomenclature recently proposed, we renamed PpSIG1* into PpSIG2, and named the novel σ factor PpSIG1. A transient expression assay using a green fluorescent protein showed that the N-terminal region of PpSIG1 acts as a chloroplast-targeting signal. Reverse transcription-PCR experiments showed that light induces the expression of the Sig1 and Sig2 genes encoding PpSIG1 and PpSIG2, respectively. Thus, PpSIG1 and PpSIG2 are likely plastid σ factors regulating plastid gene expression in response to light signals.