Genome-wide identification and characterization of cytochrome P450 monooxygenase genes in the ciliate Tetrahymena thermophila

Chengjie Fu,Wei Miao,Jie Xiong

doi:10.1186/1471-2164-10-208

Chengjie Fu, Wei Miao + Show 1 more

Open Access

https://doi.org/10.1186/1471-2164-10-208

Copy DOI

Abstract

BackgroundCytochrome P450 monooxygenases play key roles in the metabolism of a wide variety of substrates and they are closely associated with endocellular physiological processes or detoxification metabolism under environmental exposure. To date, however, none has been systematically characterized in the phylum Ciliophora. T. thermophila possess many advantages as a eukaryotic model organism and it exhibits rapid and sensitive responses to xenobiotics, making it an ideal model system to study the evolutionary and functional diversity of the P450 monooxygenase gene family.ResultsA total of 44 putative functional cytochrome P450 genes were identified and could be classified into 13 families and 21 sub-families according to standard nomenclature. The characteristics of both the conserved intron-exon organization and scaffold localization of tandem repeats within each P450 family clade suggested that the enlargement of T. thermophila P450 families probably resulted from recent separate small duplication events. Gene expression patterns of all T. thermophila P450s during three important cell physiological stages (vegetative growth, starvation and conjugation) were analyzed based on EST and microarray data, and three main categories of expression patterns were postulated. Evolutionary analysis including codon usage preference, site-specific selection and gene-expression evolution patterns were investigated and the results indicated remarkable divergences among the T. thermophila P450 genes.ConclusionThe characterization, expression and evolutionary analysis of T. thermophila P450 monooxygenase genes in the current study provides useful information for understanding the characteristics and diversities of the P450 genes in the Ciliophora, and provides the baseline for functional analyses of individual P450 isoforms in this model ciliate species.

Highlights

Cytochrome P450 monooxygenases play key roles in the metabolism of a wide variety of substrates and they are closely associated with endocellular physiological processes or detoxification metabolism under environmental exposure
T. thermophila putative P450 gene sequences The putative cytochrome P450 gene sequences in T. thermophila were initially identified in 2004 by Dr Nelson based on an early TIGR release of its macronuclear genome assemblies, and 47 P450-like genes were posted on his P450 website http://drnel
We used the data from two Expressed Sequence Tag (EST) database resources (NCBI and taxonomically broad EST database (TBestDB)) and our own reverse transcriptase polymerase chain reaction (RT-PCR) investigations to verify the accuracy of the predictions

Summary

Introduction

Cytochrome P450 monooxygenases play key roles in the metabolism of a wide variety of substrates and they are closely associated with endocellular physiological processes or detoxification metabolism under environmental exposure. The cytochrome P450 monooxygenases (P450s) constitute a conserved gene superfamily of heme-thiolate proteins ubiquitously distributed in different life forms, including prokaryotes (archaea, bacteria), unicellular eukaryotes (protists, fungi) and multicellular eukaryotes (plants and animals) [1] They play key roles in the metabolism of a wide variety of substrates, including endogenous chemicals such as steroids and other important small molecules, and xenobiotic compounds includ-. One particular example is the divergence of P450s of the common plant-animal ancestor either to synthesize biochemicals/metabolites (in plants) or to detoxify xenobiotics (in animals), followed by P450 gene expansions, especially in the plants [3] These may well reflect different survival strategies adopted between the two kingdoms, i.e. plants evolved sessile systems with P450 enzymes with more diverse and essential roles, while animals developed higher order sensory and locomotor systems, and comparatively fewer P450s [4]

Methods

Results

Conclusion