Affiliation:
1. Membrane Protein Research Group, Department of Biochemistry, University of Alberta, 474 Medical Sciences Building, Edmonton, Alberta T6G 2H7, Canada
Abstract
SUMMARY
The importance of molybdoenzymes is exemplified both by the debilitating and fatal human diseases caused by their deficiency and by their persistence throughout evolution. Here, we show that the protein fold of the molybdopyranopterin-containing domain of sulfite oxidase (the SUOX fold) can be found in all three domains of life. Analyses of sequence data and protein structure comparisons (secondary structure matching) show that the SUOX fold is found in enzymes that have quite distinct macromolecular architectures comprising one or more domains and sometimes subsidiary subunits. These are summarized as follows: (i) animal SUOXs that contain an N-terminal cytochrome
b
5
domain and an SUOX fold fused to a C-terminal dimerization domain; (ii) plant SUOX that contains an SUOX fold fused to a C-terminal dimerization domain; (iii) the YedY protein from
Escherichia coli
, which comprises only the SUOX fold; (iv) the sulfite dehydrogenase from
Starkeya novella
that contains the SUOX fold, a dimerization domain, and an additional
c
-type cytochrome subunit; and (v) the plant-type nitrate reductases, exemplified by that of
Pichia angusta
, that contain an N-terminal SUOX fold, a dimerization domain, a cytochrome
b
5
domain, and a C-terminal NADH binding flavin adenine dinucleotide-containing domain. We used the primary sequences of the proteins containing an SUOX fold to mine 559 sequences of related proteins. A phylogeny of a nonredundant subset of these sequences was generated, and the resultant clades were categorized by sequence motif analyses in the context of the available protein structures. Based on the motif analyses, cladistics, and domain conservations, we are able to postulate a plausible pathway of SUOX fold enzyme evolution.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology,Infectious Diseases
Cited by
42 articles.
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