Insect Biochemistry and Molecular Biology 31 2001 179–187 www.elsevier.comlocateibmb
Cytochrome P450 CYP6L1 is specifically expressed in the reproductive tissues of adult male German cockroaches, Blattella
germanica L.
Zhimou Wen
a
, Jeffrey G. Scott
a,
a
Department of Entomology, Comstock Hall, Cornell University, Ithaca, NY14853, USA Received 7 February 2000; received in revised form 8 June 2000; accepted 12 June 2000
Abstract
A full-length cDNA encoding a new cytochrome P450, CYP6L1, was cloned from German cockroaches, Blattella germanica. CYP6L1 has an open reading frame of 1509 nucleotides with a deduced protein of 503 amino acids and molecular mass of 57 Kd.
CYP6L1 is most similar to CYP6H1, a putative ecdysone 20-hydroxylase from Locusta migratoria. CYP6L1 mRNA was not detected in embryos nor nymphs, nor in adult females. CYP6L1 mRNA was detected only in the testes and accessory glands of
male adult German cockroaches. Given that the testes and accessory glands are the most important components of the reproductive system in male insects, the expression of CYP6L1 mRNA exclusively in these tissues strongly suggests that CYP6L1 has a role
in reproduction. Possible substrates for CYP6L1 are discussed.
2001 Elsevier Science Ltd. All rights reserved.
Keywords: Cytochrome P450 monooxygenase; Sex-specific expression; Male reproductive system; Blattella germanica; Insecta
1. Introduction
Cytochrome P450s P450s are an important enzy- matic system found in all organisms examined, including
bacteria, fungi, plants and animals. Each animal has approximately
80 Caenorhabditis
elegans, Consortium, 1998 to 90 Drosophila melanogaster,
Adams et al., 2000 P450s, and some can metabolize numerous substrates Bernhardt, 1995; Guengerich,
1995; Nebert and Gonzalez, 1987. P450s are named CYP followed by a number, letter and number indicating
the family, subfamily and individual isoform Nelson et al., 1996. In this system, individual P450s with
.40 amino acid sequence identity are usually grouped into
the same family, and those with .55 identity grouped
into the same subfamily. However, there are several exceptions. For example, CYP6A1 and CYP6B2 are
,40 identical, but are both grouped into family 6 because “sequences surrounding the conserved cysteine
Corresponding author. Tel.: +
1-607-255-7340; fax: +
1-607-255- 0939.
E-mail address: jgs5cornell.edu J.G. Scott.
0965-174801 - see front matter
2001 Elsevier Science Ltd. All rights reserved. PII: S 0 9 6 5 - 1 7 4 8 0 0 0 0 1 1 6 - 8
residue make it clear that these two genes are evol- utionarily related” Nelson et al., 1993. Given that this
nomenclature system is based on the overall sequence similarity, and that a minor change in a single amino
acid can alter substrate specificity Lindberg and Negi- shi, 1989, substrate preference cannot be assumed for
a certain P450 based on its name.
Insect P450s catalyze the metabolism of plant allelo- chemicals and insecticides, as well as physiologically
important endogenous compounds including juvenile hormones
JHs, ecdysteroids
and pheromones
Berenbaum, 1999; Feyereisen, 1999; Hodgson, 1985; Scott et al., 1998. Among the insect P450s, CYP6B1
Ma et al., 1994 and CYP6B4 Hung et al., 1997 were shown
to metabolize
plant allelochemicals
furanocoumarins. CYP6A1 Andersen et al., 1994, CYP6A2 Dunkov et al., 1997, CYP6D1 Wheelock
and Scott, 1992; Zhang and Scott, 1996 and CYP12A1 Guzov et al., 1998 have been shown to metabolize
insecticides. CYP4C7 was demonstrated to metabolize JHs and JH precursors Sutherland et al., 1998.
CYP6A1 also metabolizes JHs and their analogs Andersen et al., 1997. The cloning of these P450s
offers a great opportunity to better understand the roles
180 Z. Wen, J.G. Scott Insect Biochemistry and Molecular Biology 31 2001 179–187
of P450s in herbivore–plant interactions, insecticide resistance, insect development and physiology.
P450s have been implicated in insect reproduction Hodgson, 1985; Yu and Terriere, 1974. However, no
individual insect P450 has yet been associated with reproduction. Herein, we report cloning of the full-length
cDNA of the first sex-specific insect P450, CYP6L1, which is exclusively expressed in the reproductive sys-
tem of male adult German cockroaches. This finding has important implications for understanding the roles of
P450s in insect reproduction and may offer a potential target for the development of novel insect control agents.
2. Materials and methods
