ELSEVIER Biochimica et Biophysics Acta 1263 (1995) 75-78 BiochirnicaL et Biophysika Acta Short Sequence-Paper Cloning and characterisation of a fish aldolase B gene * Lynda Llewellyn a*b, Vimi P. Ramsurn a,b,Glen E. Sweeney a, *, Trevor Wigham b, Cecilia R.A Santos ‘, Deborah M. Power ’ a School of Molecular and Medical Biosciences, Uniuersiry of W ales, P.O. Bon 911, Cardis CFI 3US. UK b School of Pure and Applied Biology, University of W ales, P.O. Box 915, Cardifi CFI 3TL, UK ’ Unidade de Ciencias e Tecnologias Agrarias, Unuersidade do Algarue, Campus de Gambelas, Faro 8000, Portugal Received 28 December 1994; revised 18 April 1995; accepted 21 April 1995 Abstract A full length cDNA clone representing an aldolase mRNA was isolated from a sea bream (Sparus aurutu) liver cDNA library. Sequencing of this clone revealed it to encode a 364 amino acid protein with 74% amino acid identity to human aldolase B and slightly lower similarity to human aldolase A and C. In view of the sequence data and of Northern blot analysis showing strong expression of a 1.6 kb transcript in liver it was concluded that the cloned gene represents aldolase B. This clone represents the first aldolase gene to be sequenced from any fish species thus providing new data on the evolution of the vertebrate aldolase gene family. Keywords: Aldolase; Fish; Sea bream; (Spar- us aurata) Fructose-1,6-bisphosphate aldolase (E.C. 4.1.2.13) catalyses the reversible cleavage of fructose-l ,6-bisphos- phate in the glycolytic pathway, forming glyceraldehyde 3-phosphate and dihydroxyacetone phosphate. Many inver- tebrates possess a single qpe of aldolase whereas in most vertebrates in which aldolases have been studied three related isoforms, each encoded by a separate gene, are present [I]. These are aldolase A, the major form which is found mostly in muscle and is associated primarily with glycolysis, aldolase B pres’ent in liver and involved in the metabolism of fructose, and aldolase C found in brain and neural tissue. The role of aldolase B in fructose metabolism is illustrated by the association of mutations in the human aldolase B gene with hereditary fructose intolerance [2]. Correct regulation of aldolase gene expression may be required for normal cell development since the expression of aldolase genes is altered in certain disease states [3]. The evolution of the aldolase gene family has been the subject of extensive research [4-61. However, these studies have been hampered by a lack of comparative sequence * The sequence data reported in this paper have been submitted to the EMBL/GenBank Data Libraries under the accession number X82278. * Corresponding author. E-mail: sweeneyge@cardiff.ac.uk. Fax: + 44 222 874116. 0167-478 l/95/$09.50 0 1995 El sevier Science B.V. All rights reserved SSDI 0167.4781(95)00096-8 data since, with the exception of the recently described aldolase C of Xenopus Zuevis [7], all vertebrate aldolase genes cloned to date have come from mammals or birds. Aldolase B genes have been isolated and sequenced from chicken [8], rat [9], sheep [lo] and human Ill]. Here we report the cloning and sequencing of a full-length cDNA for aldolase B from a teleost fish, the sea bream (Sparus aurutu). This is the first aldolase sequence to be reported from any fish species. A cDNA library in the vector AzapII containing approx. 300000 recombinants was constructed from poly(A)+ RNA isolated from sea bream liver. To evaluate the quality of the library, ten clones were picked at random and, following automatic excision into pBluescript SK-, the 5’ and 3’ end of each clone was sequenced using a Pharmacia ALF automated sequencer. Database searches revealed one of the clones sequenced to be similar to vertebrate aldolase B. The complete sequence of this clone was then deter- mined following subcloning of appropriate restriction frag- ments into pUC18. The sequence obtained (Fig. 1) spans 1342 bases and contains an open reading frame encoding a protein of 364 amino acids (predicted molecular mass 39.6 kDa). A polyadenylation signal (AATAAA) is present 10 bases before the poly(A) tail. Fig. 2 shows a comparison of the deduced protein sequence with chicken and human al-