Interallelic complementation at the ubiquitous urease coding locus of soybean.
Soybean (Glycine max [L.] Merrill) mutant aj6 carries a single recessive lesion, aj6, that eliminates ubiquitous urease activity in leaves and callus while retaining normal embryo-specific urease activity. Consistently, aj6/aj6 plants accumulated urea in leaves. In crosses of aj6/aj6 by urease mutants at the Eu1, Eu2, and Eu3 loci, F(1) individuals exhibited wild-type leaf urease activity, and the F(2) segregated urease-negative individuals, demonstrating that aj6 is not an allele at these loci. F(2) of aj6/aj6 crossed with a null mutant lacking the Eu1-encoded embryo-specific urease showed that ubiquitous urease was also inactive in seeds of aj6/aj6. The cross of aj6/aj6 to eu4/eu4, a mutant previously assigned to the ubiquitous urease structural gene (R.S. Torisky, J.D. Griffin, R.L. Yenofsky, J.C. Polacco [1994] Mol Gen Genet 242: 404-414), yielded an F(1) having 22% +/- 11% of wild-type leaf urease activity. Coding sequences for ubiquitous urease were cloned by reverse transcriptase-polymerase chain reaction from wild-type, aj6/aj6, and eu4/eu4 leaf RNA. The ubiquitous urease had an 837-amino acid open reading frame (ORF), 87% identical to the embryo-specific urease. The aj6/aj6 ORF showed an R201C change that cosegregated with the lack of leaf urease activity in a cross against a urease-positive line, whereas the eu4/eu4 ORF showed a G468E change. Heteroallelic interaction in F(2) progeny of aj6/aj6 x eu4/eu4 resulted in partially restored leaf urease activity. These results confirm that aj6/aj6 and eu4/eu4 are mutants affected in the ubiquitous urease structural gene. They also indicate that radical amino acid changes in distinct domains can be partially compensated in the urease heterotrimer.
Goldraij
Ariel
A
Department of Biochemistry, University of Missouri, Columbia, Missouri 65211, USA.
Beamer
Lesa J
LJ
Polacco
Joe C
JC
D000483:Alleles; D000595:Amino Acid Sequence; D021902:Enterobacter aerogenes / Q000201:enzymology; D005816:Genetic Complementation Test; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics; D011487:Protein Conformation; D016415:Sequence Alignment; D013025:Glycine max / Q000201:enzymology* / Q000235:genetics*; D014508:Urea / Q000378:metabolism; D014510:Urease / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
D014508:Urea; D014510:Urease