Three new nuclear genes, sigD, sigE and sigF, encoding putative plastid RNA polymerase sigma factors in Arabidopsis thaliana

Three new nuclear genes (sigD, SigE and sigF) of Arabidopsis thaliana, enco ding putative plastid RNA polymerase a factors, were identified and analyze d. Phylogenetic analysis revealed that higher plant a factors fell into at least four distinct subgroups within a diverse protein family. In addition, Arabidopsis sig genes contained conserved chromosomal intron sites, indica ting that these genes arose ba DNA duplication events during plant evolutio n. Transcript analyses revealed two alternatively spliced transcripts gener ated from the sigD region, one of which is predicted to encode a a protein lacking the carboxyterminal regions 3 and 4. Finally, the amino-terminal se quence of the sigF gene product was shown to function as a plastid-targetin g signal using green fluorescent protein fusions, (C) 2000 Federation of Eu ropean Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.