Evidence against an interaction between the mRNA downstream box and 16S rRNA in translation initiation

Citation
I. Moll et al., Evidence against an interaction between the mRNA downstream box and 16S rRNA in translation initiation, J BACT, 183(11), 2001, pp. 3499-3505
Citations number
44
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
JOURNAL OF BACTERIOLOGY
ISSN journal
0021-9193 → ACNP
Volume
183
Issue
11
Year of publication
2001
Pages
3499 - 3505
Database
ISI
SICI code
0021-9193(200106)183:11<3499:EAAIBT>2.0.ZU;2-O
Abstract
Based on the complementarity of the initial coding region (downstream box [ db]) of several bacterial and phage mRNAs to bases 1469 to 1483 in helix 44 of 16S rRNA (anti-downstream box [adb]), it has been proposed that db-adb base pairing enhances translation in a way that is similar to that of the S hine-Dalgarno (SD)/anti-Shine-Dalgarno (aSD) interaction. Computer modeling of helix 44 on the 308 subunit shows that the topography of the 308 riboso me does not allow a simultaneous db-adb interaction and placement of the in itiation codon in the ribosomal P site. Thus, the db-adb interaction cannot substitute for the SD-aSD interaction in translation initiation. We have a lways argued that any contribution of the db-adb interaction should be most apparent on mRNAs devoid of an SD sequence. Here, we show that 30S ribosom es do not bind to leaderless mRNA in the absence of initiator tRNA, even wh en the initial coding region shows a 15-nucleotide complementarity (optimal fit) with the putative adb. In addition, an optimized db did not affect th e translational efficiency of a leaderless lambda cI-lacZ reporter construc t. Thus, the db-adb interaction can hardly serve as an initial recruitment signal for ribosomes. Moreover, we show that different leaderless mRNAs are translated in heterologous systems although the sequence of the putative a db's within helix 44 of the 308 subunits of the corresponding bacteria diff er largely. Taken our data together with those of others (M, O'Connor, T. A sai, C. L. Squires, and A. E. Dahlberg, Proc. Natl. Acad. Sci. USA 96:8973- 8978, 1999; A. La Teana, A. Brandi, M. O'Connor, S. Freddi, and C. L. Pon, RNA 6:1393-1402, 2000), we conclude that the db does not base pair with the adb.