A unique gene for 5-aminolevulinate synthase in chickens. Evidence for expression of an identical messenger RNA in hepatic and erythroid tissues.

C.J Elferink,G Srivastava,D.J Maguire,I.A Borthwick,B.K May,W.H Elliott

doi:10.1016/s0021-9258(18)61300-6

Abstract

Reports to date have led to the conclusion that there are isozymes for 5-aminolevulinate synthase in the liver and erythroid tissue of chicken. Indeed, the existence of a multigene family for chicken 5-aminolevulinate synthase has been proposed. We find no evidence to support these proposals. In this work we show that 5-aminolevulinate synthase mRNA from chicken liver and reticulocytes is identical as determined by RNase mapping and primer extension studies and that the 5-aminolevulinate synthase protein from these tissues is the same size as judged by immunoblot analysis. We also show that a single mRNA species for 5-aminolevulinate synthase is present in chicken liver, reticulocytes, brain, and heart and an avian erythroblastosis virus-transformed chicken erythroblast cell line. Southern analysis shows the presence of only one gene copy for 5-aminolevulinate synthase in the chicken haploid genome. Overall, these results lead to the conclusion that in chickens 5-aminolevulinate synthase is encoded by a unique gene and is expressed as a single mRNA species in all tissues.

Highlights

From the Adelaide University Centrefor Gene Technology, Department of Biochemistry, Universityof Adelaide, G.P.O.Box 498, Adelaide, South Australia5001, Australia
In this work we show that 5-aminolevulinate synthase mRNA from chicken liver and reticulocytes is identical as determined by RNase mapping and primeerxtension studies and that the 5-aminolevulinate synthase protein from these tissues is the same size as judged by immunoblot analysis
We show that a single mRNA species for 5-aminolevulinate synthase is present in chicken liver, reticulocytes, brain, and heart and an avian erythroblastosis virus-transformed chicken erythroblast cell line

Summary

A Unique Gene for 5-AminolevulinateSynthase in Chickens

EVIDENCE FOR EXPRESSION OF AN IDENTICAL MESSENGER RNA INHEPATIC AND ERYTHROID TISSUES*. Yamamoto et al (7) reported the existence of distinct mRNAs of different sizes coding for the enzyme in the liver, reticulocytes, brain, and other tissues of chickens This led to a proposal for the existence of an ALV synthase multigene family. Southern Anulysis-ChickengenomicDNAwas prepared as described by Mattschoss et al (8).Both genomic DNAand X cALA-S l (a genomic clone containing the entire chicken ALV synthase gene) were digested with a range of restriction enzymes, and thefragments were analyzed by electrophoresis on 0.7% agarose gels. Northern Analysis ofRNA fromDifferent Tissues-The size of ALV synthase mRNA expressed in liver and reticulocytes washed a t 2 X SSPE, 0.1% SDS a t 50 "C for 40 min. Immunoblotting was performed by the procedure of Johnson et al (22) using polyclonal hepatic ALV synthase antiserum (1)and 'z51-ProteinA (5 X lo5cpm/ml)

RESULTS

Findings

DISCUSSION