L. Wu et al., SEQUENCE AND SPATIAL REQUIREMENTS FOR THE TISSUE-INDEPENDENT AND SPECIES-INDEPENDENT 3'-END PROCESSING MECHANISM OF PLANT MESSENGER-RNA, Molecular and cellular biology, 14(10), 1994, pp. 6829-6838
Two cis-regulatory regions are required for efficient mRNA 3'-end proc
essing of the maize 27-kDa zein mRNA: a region containing a duplicated
AAUGAA poly(A) signal and a region that is present upstream from it.
Strict spatial positioning of these two regions is required for effici
ent mRNA 3'-end processing. Insertion of a stuffer sequence as short a
s 17 or 18 bp either between the upstream region and the two AAUGAA mo
tifs or between the two AAUGAA motifs drastically reduced the efficien
cy of 3'-end processing. Mutational analyses of the nucleotide prefere
nce at the fourth position of the AAUGAA motif revealed the preference
order G > A >> C or U, suggesting that AAUAAA is neither a defective
nor an optimal poly(A) Signal for the 27-kDa zein mRNA. As for the 3'
control region of the cauliflower mosaic virus (CaMV) transcription un
it, the mRNA 3'-end processing mechanism mediated by the 27-kDa zein 3
' control sequence is neither tissue nor species specific. The 3' upst
ream sequence of the 27-kDa zein gene can functionally replace that of
the CaMV transcription unit. Conversely, the CaMV upstream sequence c
an mediate mRNA polyadenylation in the presence of a duplicated 27-kDa
zein poly(A) signal. However, instead of the proximal poly(A) signal
normally used in the 27-kDa zein mRNA, the distal signal is utilized.
These results suggest that a general mechanism controls the 3'-end pro
cessing of plant mRNAs and that the cia-regulatory functions mediated
by their upstream regions are interchangeable.