Sizes, locations, and directions of transcription of two genes on a cloned maize chloroplast DNA sequence

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RESUMO

mRNA for the large subunit (LS) of ribulose-1,5-bisphosphate carboxylase [3-phospho-D-glycerate carboxylase (dimerizing), EC 4.1.1.39] of Zea mays is complementary to an uninterrupted 1600-base-pair-long chloroplast DNA sequence that has been mapped precisely within the 4350-base-pair-long chloroplast DNA fragment Bam 9 to which it had been traced earlier [Bedbrook, J. R., Coen, D. M., Beaton, A. R., Bogorad, L. & Rich, A. (1979) J. Biol. Chem. 254, 905-910]. An additional 1400-base-pair-long uninterrupted region that is colinear with a chloroplast RNA has been detected on Bam 9. The transcript from this region is part of a 2200-nucleotide-long RNA. The remainder of the DNA sequence for the 2200-base-pair RNA maps outside Bam 9. The 1600-base-pair LS gene and the gene for the 2200-nucleotide transcript are close to one another. They are separated by an untranscribed intercistronic “gap” about 330 base pairs long. These two closely packed genes are inverted on the chromosome—i.e., their 3′ termini are at opposite ends of the untranscribed gap and they map on opposite strands.

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