TY - JOUR

T1 - The A and B forms of plastid DNA-dependent RNA polymerase from mustard (Sinapis alba L.) transcribe the same genes in a different developmental context

AU - Pfannschmidt, T

AU - Link, G

N1 - Funding information: We thank Claudia Wittig and Daphne Wigg for expert technical assistance. T.P. was the recipient of a postdoctoral fellowship from the DFG. This work was supported in part by grants from the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie, Germany, to G.L.

PY - 1997/12

Y1 - 1997/12

N2 - Two RNA polymerases, termed A (cp-pol A) and B (cp-pol B), are known to be present in mustard plastids. In vitro, the two enzymes have different requirements for DNA binding, but both bind to, and transcribe from, the same set of chloroplast promoters. The B enzyme is sensitive to rifampicin (Rif), whereas the A enzyme is not. When seedlings were grown in the presence of Rif, RNA pool sizes of the photosynthesis-related plastid genes rbcL and psbA were smaller than in untreated controls, whereas transcripts of the non-photosynthetic genes rps16, trnG, rrn and rpoB remained virtually unaffected by the drug. The Rif inhibition patterns of rbcL and psbA transcripts reflect the relative abundance of the A and B enzymes at different stages and light/dark conditions. These genes can thus be transcribed by either of the two enzymes in vivo, whereas the non-photosynthetic genes are transcribed mostly or exclusively by the A enzyme, or by another Rif-resistant plastid polymerase. Among several nuclear gene transcripts that were tested for Rif inhibition, only those of the RbcS gene family for the plastid-bound small subunit of Rubisco revealed a decrease in pool size, which may imply that mechanisms exist that serve to coordinate patterns of gene expression in the different cellular compartments.

AB - Two RNA polymerases, termed A (cp-pol A) and B (cp-pol B), are known to be present in mustard plastids. In vitro, the two enzymes have different requirements for DNA binding, but both bind to, and transcribe from, the same set of chloroplast promoters. The B enzyme is sensitive to rifampicin (Rif), whereas the A enzyme is not. When seedlings were grown in the presence of Rif, RNA pool sizes of the photosynthesis-related plastid genes rbcL and psbA were smaller than in untreated controls, whereas transcripts of the non-photosynthetic genes rps16, trnG, rrn and rpoB remained virtually unaffected by the drug. The Rif inhibition patterns of rbcL and psbA transcripts reflect the relative abundance of the A and B enzymes at different stages and light/dark conditions. These genes can thus be transcribed by either of the two enzymes in vivo, whereas the non-photosynthetic genes are transcribed mostly or exclusively by the A enzyme, or by another Rif-resistant plastid polymerase. Among several nuclear gene transcripts that were tested for Rif inhibition, only those of the RbcS gene family for the plastid-bound small subunit of Rubisco revealed a decrease in pool size, which may imply that mechanisms exist that serve to coordinate patterns of gene expression in the different cellular compartments.

KW - DNA, Plant/metabolism

KW - Genes, Plant

KW - Mustard Plant/drug effects

KW - Plants, Medicinal

KW - Plastids/genetics

KW - Promoter Regions, Genetic

KW - RNA Polymerase I/genetics

KW - RNA Polymerase II/genetics

KW - Rifampin/pharmacology

KW - Seeds/drug effects

KW - Transcription, Genetic

U2 - 10.1007/s004380050621

DO - 10.1007/s004380050621

M3 - Article

C2 - 9439567

VL - 257

SP - 35

EP - 44

JO - Molecular Genetics and Genomics

JF - Molecular Genetics and Genomics

SN - 0026-8925

IS - 1

ER -