Aminoadipate reductase gene: a new fungal-specific gene for comparative evolutionary analyses

Abstract

Background: In fungi, aminoadipate reductase converts 2-aminoadipate to 2-aminoadipate 6-semialdehyde. However, other organisms have no homologue to the aminoadipate reductase gene and this pathway appears to be restricted to fungi. In this study, we designed degenerate primers for polymerase chain reaction (PCR) amplification of a large fragment of the aminoadipate reductase gene for divergent fungi.

Results: Using these primers, we amplified DNA fragments from the archiascomycetous yeast Saitoella complicata and the black-koji mold Aspergillus awamori. Based on an alignment of the deduced amino acid sequences, we constructed phylogenetic trees. These trees are consistent with current ascomycete systematics and demonstrate the potential utility of the aminoadipete reductase gene for phylogenetic analyses of fungi.

Conclusions: We believe that the comparison of aminoadipate reductase among species will be useful for molecular ecological and evolutionary studies of fungi, because this enzyme-encoding gene is a fungal-specific gene and generally appears to be single copy.

Figure 1

Reduction of 2-aminoadipate by aminoadipte reductase in fungi.

Figure 2

a) The bootstrap consensus tree of the two most parsimonious trees based on the amino acid sequences of the aminoadipate reductase. The most parsimonious trees using the Branch-and-Bound algorithm of MEGA version 2.1 [19] with 1,000 bootstrap analyses. b) The maximum likelihood phylogenetic relationships. This analysis was performed using PAML [20], version 3.1. The model of amino acid substitution by Whelan and Goldman [21] was used.