Molecular identification and functional characterization of an adenylyl cyclase from the honeybee.
Cyclic AMP (cAMP) serves as an important messenger in virtually all organisms. In the honeybee (Apis mellifera), cAMP-dependent signal transduction has been implicated in behavioural processes as well as in learning and memory. Key components of cAMP-signalling cascades are adenylyl cyclases. However, the molecular identities and biochemical properties of adenylyl cyclases are completely unknown in the honeybee. We have cloned a cDNA (Amac3) from honeybee brain that encodes a membrane-bound adenylyl cyclase. The Amac3 gene is an orthologue of the Drosophila ac39E gene. The corresponding proteins share an overall amino acid similarity of approximately 62%. Phylogenetically, AmAC3 belongs to group 1 adenylyl cyclases. Heterologously expressed AmAC3 displays basal enzymatic activity and efficient coupling to endogenous G protein signalling pathways. Stimulation of beta-adrenergic receptors induces AmAC3 activity with an EC(50) of about 3.1 microm. Enzymatic activity is also increased by forskolin (EC(50) approximately 15 microm), a specific agonist of membrane-bound adenylyl cyclases. Similar to certain biogenic amine receptor genes of the honeybee, Amac3 transcripts are expressed in many somata of the brain, especially in mushroom body neurones. These results suggest that the enzyme serves in biogenic amine signal transduction cascades and in higher brain functions that contribute to learning and memory of the bee.
Wachten
Sebastian
S
Institut für Biologische Informationsverarbeitung 1, Forschungszentrum Jülich, Jülich, Germany.
Schlenstedt
Jana
J
Gauss
Renate
R
Baumann
Arnd
A
D000262:Adenylyl Cyclases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001516:Bees / Q000235:genetics* / Q000378:metabolism*; D001679:Biogenic Amines / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D017124:Conserved Sequence / Q000502:physiology; D000242:Cyclic AMP / Q000096:biosynthesis*; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D005260:Female; D007858:Learning / Q000502:physiology; D008568:Memory / Q000502:physiology; D008969:Molecular Sequence Data; D024521:Mushroom Bodies / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000502:physiology; D015290:Second Messenger Systems / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology
D001679:Biogenic Amines; D011943:Receptors, Adrenergic, beta; D043562:Receptors, G-Protein-Coupled; D005576:Colforsin; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D009638:Norepinephrine