---
pmid: '9451450'
title: Identification of ribosomal protein S1 as a poly(A) binding protein in Escherichia
  coli.
authors:
- Kalapos MP
- Paulus H
- Sarkar N
journal: Biochimie
year: '1997'
full_text_available: false
doi: 10.1016/s0300-9084(97)82741-1
pubmed_publication_types:
- Journal Article
- Research Support, U.S. Gov't, P.H.S.
publication_type: PRIMARY_RESEARCH
---

# Identification of ribosomal protein S1 as a poly(A) binding protein in Escherichia coli.
**Authors:** Kalapos MP, Paulus H, Sarkar N
**Journal:** Biochimie (1997)
**DOI:** [10.1016/s0300-9084(97)82741-1](https://doi.org/10.1016/s0300-9084(97)82741-1)

## Abstract

1. Biochimie. 1997 Sep;79(8):493-502. doi: 10.1016/s0300-9084(97)82741-1.

Identification of ribosomal protein S1 as a poly(A) binding protein in
Escherichia coli.

Kalapos MP(1), Paulus H, Sarkar N.

Author information:
(1)Boston Biomedical Research Institute, MA 02114, USA.

To elucidate the metabolic function of mRNA polyadenylation in Escherichia coli.
we searched for a polyadenylate-binding protein as a potential mediator of the
function of the poly(A) moiety. Using a nitrocellulose filter-binding assay and
a Northwestern blot technique, a protein in the ribosomal supernatant fraction
of E coli was identified and purified to homogeneity. N-terminal sequence
analysis yielded a 25-residue sequence which corresponded to the 25 N-terminal
amino acids of protein S1, one of the proteins of the E coli 30S ribosomal
subunit. Poly(A) binding to S1 protein was inhibited by Mg2+ and Mn2+ and by ATP
and stimulated 8-fold by 100 mM KCl. The binding of S1 to poly(A) occurred with
an association constant of 3 x 10(6) M-1 and seemed to be only mildly
cooperative. Competition studies of the binding of poly(A) and poly(C) to
purified S1 protein were consistent with the presence of two polynucleotide
binding sites, of which one binds poly(A) five times more strongly than poly(C),
whereas the other binds poly(C) 50 times more strongly than poly(A). Poly(A)
bound to 30S ribosomal subunits but not to 50S ribosomes. To study possible
association of S1 with the poly(A) tracts of E coli mRNA in the process of
translation, poly(A) RNA was isolated from polysomes by oligo(dT) cellulose
chromatography and the poly(A) RNA with bound protein was eluted either directly
or after digestion with RNase T1 and A. When subjected to Western blot analysis
with antibody to S1, both poly(A) RNA and isolated poly(A) tracts revealed bound
S1 protein. The implications of these results for the possible interaction of
poly(A) tracts of mRNA and the translational machinery of E coli are discussed.

DOI: 10.1016/s0300-9084(97)82741-1
PMID: 9451450 [Indexed for MEDLINE]