Isolation and characterization of a maize chlorophyll a/b binding protein gene that produces high levels of mRNA in the dark.
A cDNA library prepared using mRNA isolated from red-light irradiated maize seedlings was screened by a difference procedure for clones that represent red-light regulated mRNA. Two such clones were found to represent mRNA for a chlorophyll a/b binding protein (CAB), and one of these (pAB1084) was used to screen a maize genomic library. One positive genomic clone (lambda AB1084) was isolated and sequenced. The gene represented by lambda AB1084, which we designate maize cab-1, contains extensive nucleotide homology within its protein coding region to CAB genes from other species. The boundaries of the transcribed region of the cab-1 gene were determined by S1 nuclease mapping. The 5' terminus of cab-1 mRNA is located 52-54 nucleotides (nt) upstream of the translation start site and 34 nt downstream of a TATA box. As in the case of petunia CAB genes, several poly(A) addition sites are present in mRNA from the cab-1 gene. The 5' flanking DNA of cab-1 contains sequences related to elements that have been implicated in the light-regulated expression of CAB and rbcS genes in other plant systems. Quantitative Northern blot hybridization analysis using a gene specific probe for cab-1 indicates that the mRNA for this gene is present at 0.4% of the total mRNA and up to 80% of the total CAB mRNA in the leaves of dark-grown seedlings. In consequence, although the degree of up-regulation by white light is only moderate (3- to 6-fold), cab-1 transcripts account for approximately 2% of the mRNA in the leaves of light-grown seedlings.
Sullivan
T D
TD
Department of Botany, University of Wisconsin, Madison 53706.
Christensen
A H
AH
Quail
P H
PH
D000595:Amino Acid Sequence; D001483:Base Sequence; D002734:Chlorophyll / Q000235:genetics*; D003624:Darkness; D005786:Gene Expression Regulation; D005796:Genes; D045342:Light-Harvesting Protein Complexes; D008969:Molecular Sequence Data; D045322:Photosynthetic Reaction Center Complex Proteins; D010940:Plant Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D015183:Restriction Mapping; D003313:Zea mays / Q000235:genetics / Q000378:metabolism
D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; D002734:Chlorophyll