Neuropeptidomics of the American Lobster Homarus americanus

Abstract

The American lobster, Homarus americanus, is not only of considerable economic importance but has also emerged as a premier model organism in neuroscience research. Neuropeptides, an important class of cell-to-cell signaling molecules, play crucial roles in a wide array of physiological and psychological processes. Leveraging the recently sequenced high-quality draft genome of the American lobster, our study sought to profile the neuropeptidome of this model organism. Employing advanced mass spectrometry techniques, we identified 24 neuropeptide precursors and 101 unique mature neuropeptides in Homarus americanus. Intriguingly, 67 of these neuropeptides were discovered for the first time. Our findings provide a comprehensive overview of the peptidomic attributes of the lobster's nervous system and highlight the tissue-specific distribution of these neuropeptides. Collectively, this research not only enriches our understanding of the neuronal complexities of the American lobster but also lays a foundation for future investigations into the functional roles that these peptides play in crustacean species. The mass spectrometry data have been deposited in the PRIDE repository with the identifier PXD047230.

Keywords: American lobster; Homarus americanus; mass spectrometry; neuropeptide; peptide identification; peptidomics.

Figure 1.

(A) The anatomy of an American lobster showing the location of the nervous system including sinus gland (SG), brain, oesophageal ganglion (OG) and stomatogastric ganglion (STG), and thoracic ganglion (TG). (B) Overall workflow for in-depth mass spectrometry analysis of lobster peptidomes.

Figure 2.

(A) Dynamic range of lobster endogenous peptide intensities across five tissue regions. The identified bioactive neuropeptides were annotated with different symbols. (B) Cumulative abundance of peptides in the lobster brain from the highest to the lowest abundance. (C) Logo plot displaying the motifs present in the N-termini and C-termini of the top 75% of endogenous peptides (by accumulative intensity).

Figure 3.

(A) Venn diagram overlaying the peptides identified in the five different lobster tissues. (B-F) The pie chart in the lower left illustrating the cumulative abundance of prohormone-derived and non-prohormone-derived peptides across the tissues, whereas the pie chart on the right delineating the cumulative abundance of peptides among different neuropeptide families within the prohormone category.

Figure 4.

The different charge states of the prohormone-derived peptides are plotted in the collision cross-section versus m/z space. The Pearson correlation coefficients (r) are denoted.

Figure 5.

(A) The putative H. americanus Natalisin sequence, marked with the identified peptides (red single-letter code amino acid sequence and blue bar underneath the sequence). Dibasic motifs are marked by bold. The putative signal peptide at the N terminus is marked in italics and underlined. (B) Sequence alignment showcasing the consensus sequence among seven Natalisin-derived peptides, with identical amino acids within aligned sequences highlighted on a black background. (C) The MS/MS spectrum of a 2+ charged peptide ions identified as EGEETHPFWVSRamdie from the neuropeptide precursor Natalisin.