title: Light-associated and processing-dependent protein binding to 5' regions of rbcL mRNA in the chloroplasts of a C4 plant.
abstract: In amaranth, a C(4) dicotyledonous plant, the plastid rbcL gene (encoding the large subunit of ribulose-1,5-bisphosphate carboxylase) is regulated post-transcriptionally during many developmental processes, including light-mediated development. To identify post-transcriptional regulators of rbcL expression, three types of analyses (polysome heel printing, gel retardation, and UV cross-linking) were utilized. These approaches revealed that multiple proteins interact with 5' regions of rbcL mRNA in light-grown, but not etiolated, amaranth plants. Light-associated binding of a 47-kDa protein (p47), observed by UV cross-linking, was highly specific for the rbcL 5' RNA. Binding of p47 occurred only with RNAs corresponding to mature processed rbcL transcripts (5'-untranslated region (UTR) terminating at -66); transcripts with longer 5'-UTRs did not associate with p47 in vitro. Variations in the length of the rbcL 5'-UTR were found to occur in vivo, and these different 5' termini may prevent or enhance light-associated p47 binding, possibly affecting rbcL expression as well. p47 binding correlates with light-dependent rbcL polysome association of the fully processed transcripts in photosynthetic leaves and cotyledons but not with cell-specific rbcL mRNA accumulation in bundle sheath and mesophyll chloroplasts.
authors.affiliation: Department of Biological Sciences, State University of New York, Buffalo, New York 14260, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: McCormac
authors.forename: H
authors.initials: H
authors.lastname: Litz
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: P D
authors.initials: PD
authors.lastname: Gollnick
authors.forename: J O
authors.initials: JO
authors.lastname: Berry
mesh_terms: D020121:5' Untranslated Regions / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects; D001798:Blood Proteins / Q000378:metabolism / Q000502:physiology*; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D008027:Light; D019684:Magnoliopsida / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D011132:Polyribosomes / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism / Q000528:radiation effects; D016601:RNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism; D012273:Ribulose-Bisphosphate Carboxylase; D014466:Ultraviolet Rays
chemical_list: D020121:5' Untranslated Regions; D001798:Blood Proteins; D010750:Phosphoproteins; D010940:Plant Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C039077:platelet protein P47; C101625:RbcL protein, plastid; D012273:Ribulose-Bisphosphate Carboxylase