Studies on the quinic acid utilisation gene (qut) cluster in Aspergillus nidulans showed that the genes encoding transcriptional activator and repressor proteins evolved by co-opting duplicated copies of genes encoding metabolic enzymes. In order to test the hypothesis that this was a general route for the genesis of regulatory proteins, the origins of the major control protein mediating nitrogen metabolite repression (an example of inter-pathway regulation) and ethanol utilisation (an example of intra-pathway regulation) in filamentous fungi were sought. The regulatory proteins mediating nitrogen metabolite repression were deduced to have originated in a duplication of genes encoding the anthranilate synthase complex which is active in the shikimate pathway. The major protein regulating ethanol utilisation was deduced to have its origin in the fusion of duplicated genes encoding the aldehyde and alcohol dehydrogenases (ALDA and ALCA). These data strongly support the view that transcriptional regulatory proteins evolve by the recruitment of functional domains provided by metabolic enzymes.
"Similar instances of amino acid homologies between pathway-speCific regulatory proteins have been suggested for the nitrate utilization pathway and anthranilate sVTIthase in IV. erassa and A. nidlilans as well the ethanol utilization regulator, AlcR, and the alcohol and aldehyde dehydrogenase proteins in A. nidlilans. This has led to a controversial hypothesis that transcriptional regulatory genes for some dispensable pathways evolved through the recruitment of functional domains from complementary metabolic pathway genes (Hawkins et al., 1993,1994). "
"Although the relationship reported by Hawkins et al. (1994) has its origin in a CLUSTAL V analysis, that analysis also contains the unverified assumption that the three sequences analyzed are homologous. An analysis such as the one presented here is a necessary adjunct to verify the assumption of homologous sequences . "
[Show abstract][Hide abstract] ABSTRACT: The suggestion that the ethanol regulatory protein from Aspergillus has its evolutionary origin in a gene fusion between aldehyde and alcohol dehydrogenase genes (Hawkins AR, Lamb HK, Radford A, Moore JD, 1994, Gene 746:145-158) has been tested by profile analysis with aldehyde and alcohol dehydrogenase family profiles. We show that the degree and kind of similarity observed between these profiles and the ethanol regulatory protein sequence is that expected from random sequences of the same composition. This level of similarity fails to support the suggested gene fusion.
[Show abstract][Hide abstract] ABSTRACT: The effect of conditionally dispensable chromosomes of Nectria haematococca MPVI on rhizosphere colonization and the identification of a gene cluster for homoserine utilization
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.