Functional aspects of cHH C-terminal amidation in crayfish species

Hyperglycemic activity of the recombinant crustacean hyperglycemic hormone B1 isoform (CHH-B1) of the Pacific white shrimp Litopenaeus vannamei

“…Additionally, the effect of rCHH-B1was 2 times higher compared with the rPej-SGP-VII-amide produced in E. coli [27]. These results suggest that even though the C-terminal amide moiety of naturally amidated CHHs is significant in conferring high hyperglycemic activity, the amino acid sequence of the C-terminus of the neurohormones and its correct structure are important not only for the hyperglycemic activity observed in some non-amidated versions of recombinant CHH isoforms that are naturally amidated [14,17,26,27], but also for the activity observed in the naturally occurring non-amidated isoforms like CHH-B1.…”

“…Some authors have observed that the presence of additional Cterminal tags could interfere with the hyperglycemic activity [52], as well as the generation of point and deletion mutants at the C-terminus [25], and forms truncated at the C-terminus lacked hyperglycemic activity [24]. In particular, C-terminal amidation has been considered to be critical for the hyperglycemic activity of alternatively spliced CHH isoforms that are naturally amidated, since differences in activity and in the conformation of the Cterminal region have been observed between C-terminal amidated and non-amidated recombinant peptides [17,26,27], and several authors have found lack of activity in some extra-eyestalk CHH-L isoforms having non-amidated C-terminal residues. However, despite isoforms originating by alternative splicing (CHH/CHH-L) share an identical N-terminal sequence (residues 1-40), they differ considerably in the remaining sequence.…”

Different transcription regulation routes are exerted by L- and D-amino acid enantiomers of peptide hormones

“…The other one, the target peptide of this study, is the XOSG-secreted CHH, after which the entire family was named. It is a 72 amino acid neuropeptide, characterized by six cysteines forming three intradisulfide bridges, p-glutamyl at its N-terminus and valyl amide at its C-terminus (Mosco et al, 2008). The Astacidea CHH is present in the circulation as a mix of two chiral isomers differing by the presence of D-or L-phenylalanine at the third N-terminus position in contrast to the exclusively L-CHH peptide of crabs (Chung and Webster, 1996).…”

Insect ion transport peptides are derived from alternatively spliced genes and differentially expressed in the central and peripheral nervous system

“…(4) N-terminal pyro-Glu, a modification known to protect peptides against aminopeptidase degradation, is a further important structural determinant that is clearly a distinctive difference between most CHHs and all hitherto known ITPs, with the exception of some shrimp CHHs (Chen et al, 2005). (5) The presence of aromatic amino acids (Phe or Tyr) in position 3 (or positions 2, 4 or 3 in dipteran ITPs) of the Nterminal putative α-helix appears to be a very conserved feature that is important for the biological activity of both CHHs and ITPs (Gu et al, 2000;Katayama et al, 2003;Katayama and Nagasawa, 2004;Mosco et al, 2008;Zhao et al, 2005). (6) The highest consensus of amino acid identities or close similarities is restricted to a core structure of the first 40 or 41 amino acids, containing two out of five important characteristic structural motifs in CHHs and ITPs embraced by the probably conserved cystine-bound loops I and II (Chen et al, 2005;Drexler et al, 2007;Lacombe et al, 1999) (Fig.…”