The trehalose transporter 1 gene sequence is conserved in insects and encodes proteins with different kinetic properties involved in trehalose import into peripheral tissues.
We recently cloned a trehalose transporter gene (Tret1) that contributes to anhydrobiosis induction in the sleeping chironomid Polypedilum vanderplanki Hinton. Because trehalose is the main haemolymph sugar in most insects, they might possess Tret1 orthologs involved in maintaining haemolymph trehalose levels. We cloned Tret1 orthologs from four species in three insect orders. The similarities of the amino acid sequence to TRET1 in P. vanderplanki were 58.5-80.4%. Phylogenetic analysis suggested the Tret1 sequences were conserved in insects. The Xenopus oocyte expression system showed apparent differences in the K(m) and V(max) values for trehalose transport activity among the six proteins encoded by the corresponding orthologs. The TRET1 orthologs of Anopheles gambiae (K(m): 45.74 +/- 3.58 mM) and Bombyx mori (71.58 +/- 6.45 mM) showed low trehalose affinity, whereas those of Apis mellifera (9.42 +/- 2.37 mM) and Drosophila melanogaster (10.94 +/- 7.70 mM) showed high affinity. This difference in kinetics might be reflected in the haemolymph trehalose:glucose ratio of each species. Tret1 was expressed not only in the fat body but also in muscle and testis. These findings suggest that insect TRET1 is responsible for the release of trehalose from the fat body and the incorporation of trehalose into other tissues that require a carbon source, thereby regulating trehalose levels in the haemolymph.
Kanamori
Yasushi
Y
Anhydrobiosis Research Unit, National Institute of Agrobiological Sciences, Ohwashi 1-2, Tsukuba, Ibaraki 305-8634, Japan.
Saito
Ayako
A
Hagiwara-Komoda
Yuka
Y
Tanaka
Daisuke
D
Mitsumasu
Kanako
K
Kikuta
Shingo
S
Watanabe
Masahiko
M
Cornette
Richard
R
Kikawada
Takahiro
T
Okuda
Takashi
T
D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D002683:Chironomidae / Q000737:chemistry / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D017124:Conserved Sequence; D005216:Fat Body / Q000378:metabolism; D006458:Hemolymph / Q000378:metabolism; D019476:Insect Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D007313:Insecta / Q000737:chemistry / Q000145:classification / Q000235:genetics; D007700:Kinetics; D008297:Male; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D017433:Protein Structure, Secondary; D014199:Trehalose / Q000378:metabolism*
D019476:Insect Proteins; D026901:Membrane Transport Proteins; D014199:Trehalose