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Molecular and Cellular Biology, May 2000, p. 3538-3549, Vol. 20, No. 10
Centre de Génétique
Moléculaire, C.N.R.S., 91198 Gif sur Yvette, France
Received 9 August 1999/Returned for modification 4 October
1999/Accepted 17 February 2000
The yeast poly(A) binding protein Pab1p mediates the interactions
between the 5' cap structure and the 3' poly(A) tail of mRNA, whose
structures synergistically activate translation in vivo and in vitro.
We found that deletion of the PAT1 (YCR077c) gene suppresses a PAB1 gene deletion and that Pat1p is
required for the normal initiation of translation. A fraction of Pat1p cosediments with free 40S ribosomal subunits on sucrose gradients. The
PAT1 gene is not essential for viability, although
disruption of the gene severely impairs translation initiation in vivo,
resulting in the accumulation of 80S ribosomes and in a large decrease
in the amounts of heavier polysomes. Pat1p contributes to the
efficiency of translation in a yeast cell-free system. However, the
synergy between the cap structure and the poly(A) tail is maintained in vitro in the absence of Pat1p. Analysis of translation initiation intermediates on gradients indicates that Pat1p acts at a step before
or during the recruitment of the 40S ribosomal subunit by the mRNA, a
step which may be independent of that involving Pab1p. We conclude that
Pat1p is a new factor involved in protein synthesis and that Pat1p
might be required for promoting the formation or the stabilization of
the preinitiation translation complexes.
0270-7306/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Deletion of the PAT1 Gene Affects
Translation Initiation and Suppresses a PAB1 Gene Deletion
in Yeast
*
Corresponding author. Mailing address: Centre de
Génétique Moléculaire, C.N.R.S., 91198 Gif sur
Yvette, France. Phone: 33 1 69 82 31 70. Fax: 33 1 69 82 32 36. E-mail:
wyers{at}cgm.cnrs-gif.fr.
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