Cytochrome P450 family 4 in a cockroach: molecular cloning and regulation by regulation by hypertrehalosemic hormone.

Abstract

Hypertrehalosemic hormone (a carbohydrate-mobilizing neuroendocrin decapepde) and starvation markedly increased levels of a cockroach (Blaberus discoidalis) fat body cytochrome P450 message. The gene represented by the cloned P450 cDNA has been named CYP4C1 (cytochrome P450 family 4, subfamily C, gene 1), a newly identified member of the ubiquitous cytochrome P450 monooxygenase gene superfamily. Blaberus CYP4C1 (511 amino acids, Mr = 58,485) has a hydrophobic NH2 terminus and a sequence near the COOH terminus that is homologous to the cysteine-containing heme-binding region definitive ofcytochromes P450. The cockroach sequence is 32-36% identical to mammalian family 4A and 4B enzymes. It contains a 13-residue sequence characteristic of family 4 but not other P450s. This study suggests that CYP4C1 is hormonally regulated in association with energy substrate mobilization and supports the idea that family 4 is an old and widespread gene family.The cytochrome P450 gene (CYPt) superfamily encodes NAD(P)H-dependent, heme-containing monooxygenases that metabolize numerous endogenous and exogenous substrates such as steroids, fatty acids, drugs, carcinogens, and pesticides (2,3). According to amino acid sequence analysis, =150 genes from the CYP superfamily have been assigned to 27 families (1), and a phylogeny of the superfamily has been proposed (1,4,5). Most P450 sequences have been obtained from vertebrates (especially mammals) but bacterial, yeast, fungal, invertebrate [including one insect (6)], and plant sequences are also described. The fact that cytochromes P450 are ubiquitous argues for descent of these proteins from a sequence that predated divergence of prokaryotes and eukaryotes.We have identified a cytochrome P450 sequence (deduced from cDNA) from the neotropical cockroach Blaberus discoidalis.t The cDNA was obtained from a fat body (analogous to vertebrate liver) library by differential hybridization designed to select gene sequences regulated by the hypertrehalosemic hormone (HTH) (7). HTH is a neuroendocrine decapeptide produced by the corpora cardiaca-paired neurosecretory glands attached to the brain. A major action for HTH is the stimulation of fat body glycogenolysis for the production of precursors for synthesis of trehalose, the main circulating carbohydrate of insects (8). HTH is a member of a large group of structurally related neuropeptides-the adipokinetic hormone/red pigment-concentrating hormone family (9)-that regulate energy substrate mobilization and metabolism in arthropods. Levels of the P450 mRNA are low in the fat body of decapitated (gland-free) adult male cockroaches, but strongly stimulated in decapitated animals by HTH administration. The P450 message is also stimulated by starvation in the presence but not in the absence of the head.Comparison of the 511-amino acid Blaberus P450 with other P450s revealed highest similarity (32-36% positional identity) with family 4 proteins, a group of microsomal enzymes that primarily catabolize fatty acids and prostaglandins (10-16). Th...

Purification and characterization of a cytochrome P‐450 from insecticide susceptible and resistant strains of housefly, Musca domestica L., before and after phenobarbital exposure

“…Also, only 35 and 74% of ECOD was inhibited at 16 and 32 pI, respectively. This suggests that P-450 immunoreactive to anti-P-4501,, 'Amino-terminal sequence of cDNA clone isolated from hypertrehalosemic hormone-induced cockroach (Blabwus) strain [30].…”

Molecular cloning of a family of xenobiotic-inducible drosophilid cytochrome P450s: Evidence for involvement in host-plant allelochemical resistance

“…In recent years, however, the cloning of cytochrome P450s from more divergent species, including arthropods, has necessitated a shift to a nomenclature system that focuses more on regional sequence identity and that takes into account the results of phylogenetic analyses. The cockroach CYP4C1, therefore, was included in the CYP4 family despite having only 32-36% positional identity with its vertebrate homologs (32). Similarly, conservation around the hemebinding decapeptide shows the evolutionary relatedness of CYP6A1 and CYP6B2 despite their Ͻ40% global sequence identity (2).…”

Variations in ecdysteroid levels and Cytochrome p450 expression during moult and reproduction in male shore crabsCarcinus maenas

“…This is in contrast to CYP330A1, which is expressed only in the hepatopancreas, and indicates that CYP4C39 has a much broader physiological role than CYP330A1, which is not directly related to ecdysteroid metabolism. Vertebrate CYP4 enzymes are involved in fatty acid metabolism (Simpson 1997), and CYP4C1 from fat bodies of insects (54% amino acid homology to CYP4C39) is controlled by the hyperglycemic hormone and most probably catalyses fatty acid oxidation (Bradfield et al 1991). The crustacean hyperglycemic hormone (CHH) controls lipids and fatty acid levels in the haemolymph of Chasmagnathus granulata and Carcinus maenas, respectively.…”