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MINIMAL SEQUENCE REQUIREMENTS FOR THE REGULATED EXPRESSION OF rbcS‐A FROM Pisum sativum IN TRANSGENIC TOBACCO PLANTS
Author(s) -
CuozzoDavis Maria,
Yong MunHeng,
Gilmartin Philip M.,
Kuhlemeier Cris,
Sarokin Laura,
Chua NamHai
Publication year - 1990
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1990.tb01753.x
Subject(s) - biology , regulatory sequence , gene , genetics , promoter , transgene , microbiology and biotechnology , gene expression
— RbcS‐3A , the most highly expressed member of the pea multigene family encoding the small subunit of ribulose 1,5‐bisphosphate carboxylase, is expressed in a light‐dependent and organ‐specific manner. In order to further delineate the sequences which mediate this complex pattern of regulation, putative regulatory sequences were assayed for function in transgenic tobacco plants in the context of an inactive 5' deleted rbcSSA test gene. We have identified a minimal functional unit of 58 bp which is able to confer organ‐specific transcriptional activity. It contains two sequences conserved among the pea rbcS family members, namely box II (‐151 to ‐138; GTGTGGTTAATATG) and box III (‐125 to ‐114; ATCATTTTCACT). These sequences bind the nuclear factor termed GT‐1 in vitro. Substitution mutations within this 58 bp element have demonstrated that sequences upstream of, or located between, boxes II and III are not required for the transcriptional activity conferred by this element. Distance and orientation of these sequences from the gene are not critical for activity within the limits tested. DNA fragments upstream of nucleotide ‐170 of rbcSSA that contain other GT‐1 binding sites can also confer regulated expression upon the rbcSSA promoter deleted to ‐50. Multimers of individual motifs, namely four tandem copies of boxes II and III, are unable to drive expression of the deleted promoter. These observations suggest that while GT‐1 binding is necessary for promoter activity it is by itself not sufficient.