ISSN:
1573-5028
Keywords:
soybean β-tubulins
;
genomic sequence
;
genomic sequence
;
protein sequence
;
interspecies sequence comparison
;
hydropathy analysis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Two divergent β-tubulin genes (designated Sβ-1 and Sβ-2) were isolated by screening a soybean genomic library with a Chlamydomonas reinhardtii β-tubulin cDNA probe. Restriction fragment analysis of the clones recovered, and of soybean genomic DNA, indicated that these represent two unique classes of structurally different β-tubulin genes in the soybean genome. However, it is possible that unidentified members of these classes or additional highly divergent classes of β-tubulin genes (thus far undetected) exist in the soybean genome. The Sβ-1 and Sβ-2 genomic clones were sequenced, revealing that both are potentially functional genes which would encode β-tubulins of 445 and 449 amino acids, respectively. A comparison of their derived amino acid sequences with β-tubulins from several organisms showed that they are most homologous to Chlamydomonas β-tubulin (85–87%), with lesser degrees of homology to β-tubulins of vertebrate species (79–83%), Trypanosoma brucei (80–81%) and Saccharomyces cerevisiae (66–68%). The amino acid sequences of Sβ-1 and Sβ-2 are as divergent from each other as they are from the Chlamydomonas β-tubulin. The amino acids at the diverged positions in Sβ-2 are nearly all conservative substitutions while in Sβ-1, 18 of the 69 substitutions were non-conservative. Both soybean β-tubulin genes contain two introns in exactly the same positions. The first soybean intron is located in the same position as the third intron of the Chlamydomonas β-tubulin genes. Codon usage in the two soybean β-tubulins is remarkably similar (D 2=0.87), but differs from codon usage in other soybean genes.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00016154
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