Control Mechanisms of Plastid Gene Expression

Involvement of Protein Kinase and Extraplastidic Serine/Threonine Protein Phosphatases in Signaling Pathways Regulating Plastid Transcription and the psbD Blue Light- Responsive Promoter in Barley

“…When transcription is markedly reduced, differences in RNA levels in OA-treated seedlings can be explained by differences in RNA decay rate and RNA stability. Severa1 studies have reported that the levels of plastid RNAs drop as chloroplasts mature (Gruissem and Tonkyn, 1993;Mullet, 1993). RNA processing extracts prepared from plastids isolated from light-grown seedlings rapidly degraded endogenous RNAs (Sexton et al, 1990a).…”

“…Developmental signals cause changes in plastid transcription, RNA stability, and splicing that occur independently of light (Barkan, 1989;Baumgartner et al, 1993;Kim et al, 1993). In addition, light influences chloroplast gene expression at transcriptional, posttranscriptional, and translational levels (Klein et al, 1988;Berry et al, 1990;Klein and Mullet, 1990;Schrubar et al, 1990;Sexton et al, 1990a;Klaff and Gruissem, 1991; for review, see Gruissem and Tonkyn, 1993;Mullet, 1993;Mayfield et al, 1995). Light activates nuclear genes for plastid ' Portions of this study were supported by funds from the University of Hawaii Research Council to D.A.C.…”

New insights into plastid nucleoid structure and functionality

“…Most preparations were done by either sucrose density gradient centrifugation (Nemoto et al 1988;Cannon et al 1997) or by gel filtration of extracts prepared from plastid membranes treated with detergents (Hallick et al 1976;Krause and Krupinska 2000). The DNA containing fraction prepared by gel filtration was called TAC, because it has been used initially to determine the activity and composition of the transcriptional apparatus (see reviews of Gruissem and Tonkyn 1993;Igloi and Kössel 1992;Sakai et al 2004, and references therein). The TAC fraction is prepared from plastid membranes by release of the nucleoids with detergents and by subsequent purification involving sepharose gel filtration and other steps (Krause and Krupinska 2000;Pfalz et al 2006).…”

Translation of the psbA mRNA of Chlamydomonas reinhardtii requires a structured RNA element contained within the 5' untranslated region.

“…Additional regulatory signals, involving interactions of the chloroplast and nucleus, have also been identified as having regulatory roles in coordinate gene expression (Mayfield, 1990), but the nature of these signals remains unclear (Susek et al, 1993). In addition to translational regulation, several key steps in chloroplast gene expression have been identified as crucial to photosynthetic protein accumulation, including those affecting mRNA transcription (Deng and Grnissem, 1988;Mullet, 1993) Schuster, 1993;Salvador et al, 1993), and protein turnover (Mullet et al, 1990). To date, none of the regulators of these processes have been characterized.…”