J Biol Chem, Vol. 273, Issue 38, 24379-24386, September 18, 1998
Purification, Cloning, and Preliminary Characterization of a
Spiroplasma citri Ribosomal Protein with DNA Binding
Capacity
Loïck
Le Dantec
,
Michel
Castroviejo¶,
Joseph M.
Bové
, and
Colette
Saillard
From the
Laboratoire de Biologie Cellulaire et
Moléculaire, Institut National de la Recherche Agronomique and
Université Victor Segalen Bordeaux 2,
33883 Villenave d'Ornon Cedex and the ¶ Institut de
Biochimie et Génétique Cellulaires and Centre National de
la Recherche Scientifique, 33077 Bordeaux Cedex, France
The
rpsB-tsf-x operon of
Spiroplasma citri encodes ribosomal protein S2 and
elongation factor Ts, two components of the translational apparatus,
and an unidentified X protein. A potential DNA-binding site
(a 20-base pair (bp) inverted repeat sequence) is located at the 3' end
of rpsB. Southwestern analysis of S. citri
proteins, with a 30-bp double-stranded oligonucleotide probe (IRS),
containing the 20-bp inverted repeat sequence and the genomic flanking
sequences, detected an IRS-binding protein of 46 kDa (P46). P46
protein, which displays preferential affinity for the IRS, was purified from S. citri by a combination of affinity and gel
filtration chromatographies. The native form of P46 seems to be
homomultimeric as estimated by SDS-polyacrylamide gel electrophoresis
analysis and gel filtration. A 3.5-kilobase pair S. citri
DNA fragment comprising the P46 gene and flanking sequences was cloned
and sequenced. Sequence analysis of this DNA fragment indicated that the P46 gene is located within the S10-spc operon of
S. citri at the position of the gene coding for ribosomal
protein L29 in the known S10-spc operons. The similarity
between the N-terminal domain of P46 and the L29 ribosomal protein
family and the presence of a 46-kDa IRS-binding protein in S. citri ribosomes indicated that P46 is the L29 ribosomal protein
of S. citri. We suggest that P46 is a bifunctional protein
with an L29 N-terminal domain and a C-terminal domain involved in IRS
binding.
Copyright © 1998 by The American Society for Biochemistry and Molecular Biology, Inc.