Two genetic variants of the crustacean hyperglycemic hormone (CHH) from the Australian crayfish, Cherax destructor: detection of chiral isoforms due to posttranslational modification.
From sinus glands of the Australian crayfish Cherax destructor, two genetic variants of the crustacean hyperglycemic hormone (CHH) were isolated by HPLC and fully characterized by mass spectrometry and Edman sequencing. Both CHH A (8350.38 Da) and CHH B (8370.34 Da) consist of 72 amino acid residues, with pyroGlu as N-terminus and an amidated (Val-NH2) C-terminus. They differ in 14 residues (81% identity). Both sequences are significantly different from those of the hitherto known three CHHs of Astacoidea species (Northern hemisphere crayfish), which among themselves are extremely conserved. This may reflect the long, separate evolution of the Astacoidea lineage and the Parastacoidea (Southern hemisphere crayfish) lineage, to which Cherax belongs. CHH A and CHH B genes are expressed at comparable levels, as indicated by the similar amounts of mature peptides in the sinus gland. In addition to each of the major peptides, which share the identical N-terminal tripeptide pyroGlu-Val-L-Phe, one chiral isoform containing pyroGlu-Val-D-Phe was identified. Compared to the main peptides, the amounts of the D-isoforms are lower, but significant, amounting to 30-40% of L-isoforms. These results demonstrate that two genes can give rise to a total of four different peptides in the secretory terminals of the sinus gland. All peptides gave a highly significant hyperglycemic in vivo response in C. destructor.
Bulau
Patrick
P
Institute for Zoophysiology, University of Bonn, Endenicher Allee 11-13, D-53115 Bonn, Germany. PBulau@compuserve.de
Meisen
Iris
I
Reichwein-Roderburg
Barbara
B
Peter-Katalinić
Jasna
J
Keller
Rainer
R
D000595:Amino Acid Sequence; D000818:Animals; D060829:Arthropod Proteins; D003400:Astacoidea / Q000235:genetics*; D001315:Australia; D014644:Genetic Variation; D007447:Invertebrate Hormones; D007532:Isoleucine / Q000032:analysis / Q000235:genetics; D007930:Leucine / Q000032:analysis / Q000235:genetics; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics*; D010455:Peptides / Q000235:genetics; D020033:Protein Isoforms / Q000032:analysis* / Q000235:genetics / Q000302:isolation & purification; D011499:Protein Processing, Post-Translational / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
D060829:Arthropod Proteins; D007447:Invertebrate Hormones; D009419:Nerve Tissue Proteins; D010455:Peptides; D020033:Protein Isoforms; C015947:hyperglycemic hormone, crustacean; D007532:Isoleucine; D007930:Leucine