Sequence of a cDNA clone encoding an Atlantic salmon ribosomal protein

Gene. 101 (1991) 303-304 0 1991 EIsevier Science Publishers

GENE

303

B.V. 037X-i 119/91/SO3.50

04013

Brief Notes Sequence of a cDNA clone encoring an Atlantic salmon ribosoma1 protein* (Recombinant

fish; Salmo sular; homologies

DNA;

to rat and Xenopus genes)

Richard Powell”, Lucy Bymesa and Frank GannonsTb ” Depart~lent of ~jcro~j~l~gy, UniversityCollege, Galway (Ireland~ and ’ ~~t~o~aID~~gno~tic~Centrel~~o~e~earch Ireland, U~i~,ers~ty College, Galway ~Ireland~ Tel. (44-3S3-9~~66~j9 Received by H. van Ormondt: 22 August Revised: 2 November 1990 Accepted: 12 November 1990

1990

SUMMARY

We report here the nucleotide sequence of a cDNA clone encoding a salmon (Salmo salar) ribosomal (r) protein. The encoded protein shows 62.3% and 62% similarity with the L14 and L18 r-proteins in Xenopus laevis and rat, respectively.

As part of our analysis of genes which are expressed in the liver of Atlantic salmon, a cDNA clone has been isolated from a phage AgtlO library constructed from poly(A)+ RNA prepared from salmon liver (Byrnes and Gannon, 1990). The clone has been sequenced in its entirety and is 623 nt Iong (Fig. I). It encompasses an ORF corresponding to 189 codons, a 5’-untranslated region of 57 nt and a 3’untranslated region of 39 nt. A polyadenylation consensus signal (AATAAA) is found 19 nt from the 3’ terminus of the clone; no poly(A) tail was found. Hybridization with the clone against the cDNA library reveals that it represents an abundant mRNA corresponding to 1 “/b of the salmon liver mRNA. Northern-blot analysis, using the clone against total RNA prepared from six different salmon tissues, including liver, detects one 0.6-kb mRNA in all tissues (Fig. 2).

Correspondence University

to:

College,

Dr.

Fax (44-3j3-91)25700. * On request, the authors the conclusions Abbreviations:

R.

Galway

reached aa, amino

Powell, (Ireland)

Department

of

Microbiology,

Tel. (44-353-91)24411

will supply detailed

experimental

ext. 2404; evidence

for

in this Brief Note, acid(s);

plementary to mRNA; kb, kilobase open reading frame; r, ribosomal.

bp, base pair(s);

cDNA,

DNA com-

or 1000 bp; nt, nucleotide(s);

ORF,

Densitometric comparisons of the signal intensities of the hybridizing mRNA in the different tissues shows fluctuating levels of this message among the various total mRNAs: intestine, 1.6 7, ; gonad, 0.2 y0 ; muscle, 1.4 %, spleen, 0.4 % ; liver, 1 y/, ; and kidney, 2”/, . Comparison of the aa sequence deduced from the ORF with the GenBank sequence data revealed significant similarity to rat L18 r-protein (62% identity rising to 86.6% with conserved replacements), Xenopus laevis L14 ribosomal protein (62.3 % identity rising to 85.8:‘;) and yeast rp28 r-protein (37.5% identity rising to 67.1%). The r-proteins usually contain 20-300/, basic residues which are supposed to facilitate their strong interaction with the acidic rRNA and this is also reflected in the deduced salmon aa sequence which holds 23% basic residues. Rat L18 has 28”/, (Devi et al., 1988), Xenopus L14 has 26% (Beccari et al., 1986) and yeast rp28 has 24% (Molenaar et al., 1984) basic residues. Hydrophobicity plot comparisons of the four aa sequences show a very similar structure. The above homology levels are appreciably higher than those found when comparing other salmon genes such as those encoding apolipoprotein A-l and serum albumin to their mammalian counterparts (Byrnes and Gannon, 1990). This may reflect stronger structural constraints on these proteins during evolution.

IJMSLK

Fig. 2. Northern-blot EtdBr-staining intestine

analysis

of 10 pg of total

data; not shown) prepared

RNA (as judged

from different

from

salmon tissues,

(I), gonad (J), muscle (M), spleen (S), liver (L) and kidney (K),

and probed

with the salmon

r-protein-encoding

cDNA

clone.

REFERENCES Beccari, Fig. I. The nt sequence and its deduced underlined.

of the cloned

aa sequence.

GenBankiEMBL

salmon

r-protein-encoding

The polyadenylation accession

consensus

gene signal is

No. is X52238.

E., Mazzati,

for the ribosomal homologies

We thank E. Powell and T. Nestor for DNA sequencing, and G. Fleming for densitometry. This work was supported by the European Community Biotechnology Action Programme.

I.: Sequences

coding

in the 5’ untranslated

region are shared with other r-pro-

teins mRNAs. Nucleic Acids Res. 14 (1986) 7633-7646. Byrnes, L. and Gannon, F.: Atlantic salmon (Salvo s&r) serum albumin: cDNA

ACKNOWLEDGEMENTS

P., Mileo, A.M. and Bozzoni,

protein L14 in Xenopus laevis and Xenopus tropic&;

sequence,

evolution

and tissue

expression.

Biol. 9 (1990) 647-655. Devi, K.R.G., Chan, Y.-L. and Wool, I.G.: The primary

DNA Cell

structure

of rat

ribosomal protein L18. DNA 7 (1988) 157-162. Lewin, B. (Ed.): Genes III. Wiley, New York, 1987, pp. 144-158. Molenaar,

C.M.T., Woudt,

L.P., Jansen,

A.E.M.,

Mager,

W.H., Planta,

R.J., Donovan, D.M. and Pearson, N.J.: Structure and organization of two linked ribosomal protein genes in yeast. Nucleic Acids Res. 12 (1984) 7345-7358.