Proteomic analysis of digestive tract peptidases and lipases from the invasive gastropod Pomacea canaliculata.

BACKGROUND
Regardless of the attention the invasive gastropod Pomacea canaliculata has received in the last decades for its negative impact on crops agriculture; knowledge of their digestive physiology remains incomplete, particularly the enzymatic breakdown of macromolecules such as proteins and lipids.


RESULTS
Discovery proteomics revealed aspartic peptidases, cysteine peptidases, serine peptidases, metallopeptidases, and threonine peptidases, as well acid and neutral lipases and phospholipases along the digestive tract of P. canaliculata. Peptides specific to peptidases (139) and lipases (14) were quantified by targeted mass spectrometry. Digestion begins in the mouth by diverse salivary peptidases (9 serine peptidases; 7 cysteine peptidases, 1 aspartic peptidase, and 22 metallopeptidases) and then continues in the oesophagus (crop) by 3 luminal metallopeptidases (family M12) and 6 serine peptidases (family S1). Downstream, the digestive gland provides a battery of enzymes composed of aspartic peptidase (1), cysteine peptidases (9), serine peptidases (12), and metallopeptidases (24 including aminopeptidases, carboxypeptidases and dipeptidases). The coiled gut has M1 metallopeptidases that complete the digestion of small peptides. Lipid extracellular digestion is completed by triglyceride lipases.


CONCLUSION
From an integrative physiological and anatomical perspective, Pomacea canaliculata shows an unexpected abundance and diversity of peptidases, which participate mainly in extracellular digestion. Moreover, the previously unknown occurrence of luminal lipases from digestive gland are reported for the first time. Salivary and digestive glands were the main tissues involved in the synthesis and secretion of these enzymes, but the few luminally exclusive peptidases are plausibly secreted by ventrolateral pouches or epithelial unicellular glands.